University of Veterinary Medicine Hannover Influence of ... · Prof. Dr. Elisabeth grosse Beilage...

University of Veterinary Medicine Hannover

Influence of raw material and weaning management on the

occurrence of tail-biting in undocked pigs

INAUGURAL–DISSERTATION

in partial fulfillment of the requirements of the degree of

Doctor of Veterinary Medicine

-Doctor medicinae veterinariae-

(Dr. med. vet.)

submitted by

Christina Veit

Neunkirchen/ Saar

Hannover 2016

Academic supervision: 1. Prof. Dr. Elisabeth grosse Beilage

Field Station for Epidemiology (Bakum)

University of Veterinary Medicine

Hannover, Germany

2. Prof. Dr. Joachim Krieter

Institute of Animal Breeding and Husbandry

Christian-Albrechts-University

Kiel, Germany

1. Referee: Prof. Dr. Elisabeth grosse Beilage

Field Station for Epidemiology (Bakum)


Hannover, Germany

2. Referee: Prof. Dr. Karl-Heinz Waldmann

Clinic for Swine and Small Ruminants,

Forensic Medicine and Ambulatory Services


Hannover, Germany

Day of the oral examination: 03.05.2016

Die Dissertation wurde mit dankenswerter finanzieller Unterstützung des Ministeriums

für Energiewende, Landwirtschaft, Umwelt und ländliche Räume Schleswig-Holstein

sowie der Landwirtschaftlichen Rentenbank angefertigt.

Meiner Familie

Christina Veit: Influence of raw material and weaning management on the occurrence

of tail-biting in undocked pigs

TABLE OF CONTENTS

GENERAL INTRODUCTION………………………………………………………………...1

LITERATURE REVIEW

Literaturübersicht zur Verhaltensstörung “Schwanzbeißen” beim Schwein……………….….6

MATERIAL AND METHODS………………………………………………………………29

CHAPTER ONE

Influence of raw material on the occurrence of tail-biting in undocked pigs……..……….....41

CHAPTER TWO

The effect of mixing after weaning on tail-biting during rearing with characterisation of

performers and receivers of manipulative behavioral patterns……………………………….63

GENERAL DISCUSSION…………………………………………………………..……….85

GENERAL SUMMARY……………………………………………………………..………95

ZUSAMMENFASSUNG………………………………………………………………….....98

1

GENERAL INTRODUCTION

Tail-biting in pigs is a widespread behavioural disorder in intensive pig husbandry with

multifactorial causes. Three different forms are known: “two-stage biting”, “sudden forceful

biting” as well as “obsessive biting” (Taylor et al., 2010). The differences are determined on

one hand by the manner of expression and on the other hand by the causes associated with

this behaviour. Generally, tail-biting is defined as injury to the tail in different degrees of

severity through manipulations with the mouth. Tail-docking, which has so far been classified

as the safest measure to reduce this behavioural disorder, is forbidden according to European

law (2001/ 93/ EG) and does not solve the underlying mechanisms. The possible risks which

can bring about tail-biting are environmental factors such as a lack of rooting substrate

(Zonderland et al., 2008), poor ventilation (Hunter et al., 2001), higher stocking densities and

deficiencies in feed quality or accessibility (Moinard et al., 2003), as well as group size and

group composition (Zonderland et al., 2010). On the biological side, poor health (Day et al.,

2002), breed (Breuer et al., 2003) and gender (Zonderland et al., 2010) could play a role in the

development of the behavioural disorder. Depending on the individual circumstances

encountered on farms, different stressors influence the animals and require them to activate

their coping ability. An overextension of the adaptive capacity may trigger tail-biting. The

possible consequences of tail-biting are a reduction in animal welfare due to pain, infection

and lameness, as well as economic losses due to reduced carcass qualities (Harley et al., 2014;

Huey, 1996).

The need to perform exploration and foraging behaviour is considered to be a major

underlying motivation for tail-biting. When suitable material is unavailable, pigs may redirect

their exploratory behaviour towards other pigs and pen surroundings (EFSA, 2007). Several

studies have shown a reduction in tail-biting through environmental enrichment with straw

(Day et al., 2008; Van de Weerd et al., 2006) or other material which can be rooted (Sneddon

et al., 2001). Environmental enrichment reduces time spent involved in harmful social and

aggressive behaviour (Beattie et al., 2000). Pigs in barren environments often show higher

frequencies of manipulating floor and walls, nudging litter mates and tail-biting litter mates

than pigs in enriched conditions (Petersen et al., 1995). Rooting materials for pigs should

meet the requirements of their natural exploratory behaviour, which includes rooting, sniffing,

biting and chewing (Studnitz et al., 2007). Manipulation is therefore an important aspect of

2

stimulation and emphasises the importance of the characteristics “ingestible”, “chewable”,

“deformable” and “destructible“ for suitable material (Van de Weerd et al., 2003).

Another feature of tail-biting is the period in which it occurs, which in long-tailed piglets is

mainly the rearing phase. A temporal connection between the occurrence of the behavioural

disorder and the weaning process has already been identified (Abriel and Jais, 2013). Pigs in

intensive husbandry today are faced with several challenges. The most massive break in the

piglets’ life cycle is the weaning process i.e. separation from the sow, which is usually

accompanied by a change in housing environment and diet. Furthermore, sorting of litters by

size and gender, i.e. the mixing of unacquainted conspecifics is usual management process.

Environmental factors which disturb the normal hierarchy can result in frustration and

aggression (Schrøder-Petersen and Simonsen, 2001) and may, in turn, increase the risk of tail-

biting. According to Hötzel et al. (2011), the mixing of litters implicates higher frequencies of

agonistic and exploratory behaviours, lower resting frequencies and a higher proportion of

severe skin lesions. Although the effect of social status and events such as mixing on tail-

biting have received limited attention, mixing may act to trigger tail-biting under commercial

conditions (EFSA, 2007).

The aim of the present thesis was to adapt housing conditions in pig husbandry in order to

enable piglets to perform their natural behavioural patterns such as exploration and rooting.

The required measures were implemented under practical conditions without strong

interventions in the management process on the farms. Focus was given to the provision of

raw material and the avoidance of stress through regrouping after weaning. Furthermore,

information about pigs’ activity behaviour and occupation with the material provided was

obtained by video observation. The present thesis consists of three parts, a literature review, a

study on environmental enrichment (Chapter One) and a study on weaning management

(Chapter Two).

The literature review highlights the different forms of tail-biting, the legal foundations for

docking, the risk factors for the behavioural disorder and possible indicators for an upcoming

outbreak.

The main issue of Chapter One is the provision of manipulable material (alfalfa hay and corn

silage) for undocked pigs and its influence on the development of tail-biting. Another aspect

represents the activity behaviour of the piglets analysed by video observations.

3

Chapter Two emphasises the effect of mixing on tail-biting during rearing. Furthermore,

performers and receivers of manipulative behavioural patterns are characterised regarding

their behaviour five days prior to a tail-biting outbreak and on the day of an outbreak itself.

Conclusions to be drawn concerning the measures, the provision of raw material and the

avoidance of mixing after weaning in order to prevent tail-biting are discussed

comprehensively.

References

2001/ 93/ EG. Richtlinie 2001/ 93/ EG der Kommission vom 9. November 2001 zur

Änderung der Richtlinie 91/ 630/ EWG über Mindestanforderungen für den Schutz

von Schweinen.

Abriel, M., and C. Jais. 2013. Influence of housing conditions on the appearance of

cannibalism in weaning piglets. Landtechnik 68: 389-393.

Beattie, V. E., N. E. O'Connell, and B. W. Moss. 2000. Influence of environmental

enrichment on the behaviour, performance and meat quality of domestic pigs.

Livestock Production Science 65: 71-79.

Breuer, K. et al. 2003. The effect of breed on the development of adverse social behaviours in

pigs. Applied Animal Behaviour Science 84: 59-74.

Day, J. E. L. et al. 2002. The effects of prior experience of straw and the level of straw

provision on the behaviour of growing pigs. Applied Animal Behaviour Science 76:

189-202.

Day, J. E. L., H. A. Van de Weerd, and S. A. Edwards. 2008. The effect of varying lengths of

straw bedding on the behaviour of growing pigs. Applied Animal Behaviour Science

109: 249-260.

EFSA. 2007. Scientific report on the risks associated with tail biting in pigs and possible

means to reduce the need for tail docking considering the different housing and

husbandry systems. The EFSA Journal 611: 1-13.

Harley, S. et al. 2014. Docking the value of pigmeat? Prevalence and financial implications of

welfare lesions in irish slaughter pigs. Animal Welfare 23: 275-285.

Hötzel, M. J., G. P. P. de Souza, O. A. D. Costa, and L. C. P. Machado Filho. 2011.

Disentangling the effects of weaning stressors on piglets' behaviour and feed intake:

4

Changing the housing and social environment. Applied Animal Behaviour Science

135: 44-50.

Huey, R. J. 1996. Incidence, location and interrelationships between the sites of abscesses

recorded in pigs at a bacon factory in northern ireland. The Veterinary record 138:

511-514.

Hunter, E. J., T. A. Jones, H. J. Guise, R. H. C. Penny, and S. Hoste. 2001. The relationship

between tail biting in pigs, docking procedure and other management practices. The

Veterinary Journal 161: 72-79.

Moinard, C., M. Mendl, C. J. Nicol, and L. E. Green. 2003. A case control study of on-farm

risk factors for tail biting in pigs. Applied Animal Behaviour Science 81: 333-355.

Petersen, V., H. B. Simonsen, and L. G. Lawson. 1995. The effect of environmental

stimulation on the development of behaviour in pigs. Applied Animal Behaviour

Science 45: 215-224.

Schrøder-Petersen, D. L., and H. B. Simonsen. 2001. Tail biting in pigs. The Veterinary

Journal 162: 196-210.

Sneddon, I. A., V. E. Beattie, N. Walker, and R. N. Weatherup. 2001. Environmental

enrichment of intensive pig housing using spent mushroom compost. Animal Science

72: 35-42.

Studnitz, M., M. B. Jensen, and L. J. Pedersen. 2007. Why do pigs root and in what will they

root?:A review on the exploratory behaviour of pigs in relation to environmental

enrichment. Applied Animal Behaviour Science 107: 183-197.

Taylor, N. R., D. C. J. Main, M. Mendl, and S. A. Edwards. 2010. Tail-biting: A new

perspective. The Veterinary Journal 186: 137-147.

Van de Weerd, H. A., C. M. Docking, J. E. L. Day, P. J. Avery, and S. A. Edwards. 2003. A

systematic approach towards developing environmental enrichment for pigs. Applied

Animal Behaviour Science 84: 101-118.

Van de Weerd, H. A. V. d., C. M. Docking, J. E. L. Day, K. Breuer, and S. A. Edwards. 2006.

Effects of species-relevant environmental enrichment on the behaviour and

productivity of finishing pigs. Applied Animal Behaviour Science 99: 230-247.

5

Zonderland, J. J., M. B. M. Bracke, L. A. den Hartog, B. Kemp, and H. A. M. Spoolder. 2010.

Gender effects on tail damage development in single- or mixed-sex groups of weaned

piglets. Livestock Science 129: 151-158.

Zonderland, J. J. et al. 2008. Prevention and treatment of tail biting in weaned piglets.

Applied Animal Behaviour Science 110: 269-281.

6

LITERATURE REVIEW

Literaturübersicht zur Verhaltensstörung „Schwanzbeißen“ beim Schwein

Review of the behavioural disorder tail-biting in pigs

Christina Veit1, Elisabeth große Beilage², Joachim Krieter1

1Institut für Tierzucht und Tierhaltung, Christian-Albrechts-Universität, Kiel 2Außenstelle für Epidemiologie, Stiftung Tierärztliche Hochschule, Hannover

Originalpublikation:

Veit C, grosse Beilage E, Krieter J (2016): Literaturübersicht zur Verhaltensstörung Schwanzbeißen beim Schwein. Prakt Tierarzt 97(3): 232–241, Schlütersche, Hannover.

7

Zusammenfassung

Schwanzbeißen beim Schwein ist eine Verhaltensstörung mit multifaktoriellen Ursachen, die

seit der Intensivierung der Nutztierhaltung auftritt. Drei verschiedene Formen sind bekannt:

„zweistufiges Beißen“, „plötzliches gewaltsames Beißen“ und „obsessives Beißen“. Die

Unterschiede liegen zum einen in der Art und Weise der Ausübung des Verhaltens und zum

anderen in den Ursachen, die diesem Verhalten zugrunde liegen. Schwanzbeißen ist definiert

als das Verletzen des Schwanzes durch Manipulation mit dem Maul in unterschiedlichen

Schweregraden. Das Kupieren der Schwänze, welches bisher als sicherste Maßnahme zur

Verminderung der Verhaltensstörung gilt, ist laut EU-Gesetzgebung und deutschem

Tierschutzgesetz verboten und behebt die zugrundeliegenden Ursachen nicht. Mögliche

Risikofaktoren für Schwanzbeißen sind neben umweltbedingten Faktoren wie z. B.

mangelnde Beschäftigung, Absetzmanagement, Klima/ Lüftung, Fütterung, Belegdichte,

Gruppengröße und Gruppenzusammensetzung, auch tierspezifische Faktoren wie z. B.

Gesundheitszustand, Genetik und Geschlecht. Je nach Betriebssituation wirken

unterschiedliche Stressoren auf die Tiere ein, die bei Überschreitung ihrer

Anpassungsfähigkeit zur Auslösung der Verhaltensstörung führen können. Folgen des

Schwanzbeißens sind neben Verminderung des Tierwohls durch Schmerzen, Leiden und

Schäden auch wirtschaftliche Einbußen durch reduzierte Schlachtkörperqualitäten. Die

Haltungsbedingungen müssen dahingehend verändert werden, dass die Stressbelastung für die

Tiere (u. a. durch Verhinderung des Ausübens angeborener Verhaltensweisen) reduziert wird.

Die vorliegende Arbeit gibt eine Übersicht über den Stand der Forschung und mögliche

Lösungsansätze zur Problematik des Schwanzbeißens.

Summary

Tail-biting in pigs is a behavioural disorder with multifactorial causes which occurs since the

intensification of farm animal production. Three different forms are known: “two-stage

biting”, “sudden forceful biting” and “obsessive biting”. Differences exist in the manner of

how the behaviour is expressed, as well as in the underlying causes. Generally, tail-biting is

defined as injury to the tail of different degrees of severity through manipulations with the

mouth. The docking of tails, which has been hitherto classified as the best measure to prevent

tail lesions, is forbidden according to European and German law and does not solve the

8

underlying problems. Possible risk factors for tail-biting are on one hand environmental

factors, such as insufficient enrichment, weaning management, climate/ ventilation, feeding,

stocking density, group size and group composition, and on the other hand animal-specific

factors, such as health status, genetic and gender. Depending on the particular farm situation,

the pigs are influenced by different stressors which can trigger the behavioural disorder in

case of overtaxed coping abilities. In addition to a reduction of animal welfare through pain,

suffering and injuries, the consequences of tail-biting also include economical losses through

reduced carcass quality. The housing conditions must be changed in a way that the stress level

for the animals (e. g. through avoidance of expression of natural behaviours) is reduced. The

present review provides an overview of the state of research and possible solution strategies

for the issue of tail-biting.

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Einleitung

Schwanzbeißen ist eine weit verbreitete Verhaltensstörung in der intensiven Schweinehaltung,

die ein eingeschränktes Tierwohl und wirtschaftliche Einbußen zur Folge hat (EFSA, 2007).

Die Prävalenz von Schwanzverletzungen wurde bisher überwiegend durch Erhebungen am

Schlachthof ermittelt und liegt in den europäischen Ländern bei kupierten Tieren im Mittel

bei 3 % und bei unkupierten Tieren bei 6-10 % bis hin zu 30 % (EFSA, 2007). Bei der

Bewertung der Prävalenzschätzungen an kupierten Tieren ist allerdings zu bedenken, dass die

Erhebung das Problem möglicherweise unterschätzt, da abgeheilte Verletzungen an kupierten

Schwänzen oft nicht mehr als solche erkannt werden. Die tatsächliche Prävalenz in den

Betrieben kann von den am Schlachthof erhobenen Daten zudem abweichen, da die

Abgangsraten aufgrund von Schwanzverletzungen nicht berücksichtigt werden können

(EFSA, 2007).

Die gesundheitlichen Beeinträchtigungen durch Schwanzbeißen ergeben sich aus der

Verletzung selbst, in einigen Fällen aber auch durch Infektionen, die aufsteigend bei

Erreichen des Rückenmarkes zur Abszessbildung mit nachfolgender Hinterhandlähmung

führen bzw. nach einem Eindringen der Keime eine Pyämie verursachen (Huey, 1996). Die

Keimansiedlung und Abszessbildung im Körper führen dazu, dass vermehrt Schlachtkörper

verworfen werden müssen, was wirtschaftliche Schäden zur Folge hat (Harley et al., 2014).

Außerdem sind die Zunahmen bei den Opfern von Schwanzbeißen geringer (Camerlink et al.,

2012). Im Folgenden werden die verschiedenen Formen der Verhaltensstörung, die

gesetzlichen Grundlagen für das Kupieren, Risikofaktoren für Schwanzbeißen sowie

mögliche Indikatoren eines bevorstehenden Ausbruches dargestellt.

Formen des Schwanzbeißens

In der Literatur sind verschiedene Formen von Schwanzbeißen beschrieben. Taylor et al.

(2010) differenzieren ein „zweistufiges Beißen“ von plötzlich auftretendem „gewaltsamen

Beißen“ und „obsessivem Beißen“. Die Unterschiede zwischen diesen drei Formen der

Verhaltensstörung liegen zum einen in der Art und Weise der Ausübung des Verhaltens und

zum anderen in den Ursachen, die diesem Verhalten zugrunde liegen.

„Zweistufiges Beißen“: Diese Form des Schwanzbeißens beginnt spielerisch mit einem

sogenannten „tail-in-mouth behaviour“ (Schrøder-Petersen et al., 2003), welches als

10

physiologisches Erkundungsverhalten der Tiere gewertet wird. Während dieses Stadiums hat

ein Schwein den Schwanz eines anderen im Maul und manipuliert ihn, ohne sichtbaren

Schaden anzurichten (Taylor, et al., 2010). Im Falle unzureichender

Beschäftigungsmöglichkeiten kann der unbefriedigte Erkundungs- und Wühltrieb zu

vermehrten/ verstärkten Manipulationen am Schwanz und dabei zu Verletzungen der Haut

führen (Schrøder-Petersen, et al., 2003). Ist diese Stufe erreicht, steigert das austretende Blut

und Wundsekret die Attraktivität der verletzten Schwänze für die Buchtengenossen, die

dadurch animiert, vermehrt Schwanzbeißen zeigen können. Eine wichtige Maßnahme zur

Reduktion ist eine intensive Tierbeobachtung und eine sofortige Bereitstellung von

zusätzlichem Beschäftigungsmaterial zur Ablenkung der Tiere (Veit et al., 2014).

„Plötzliches und gewaltsames Beißen“: Diese Form des Schwanzbeißens zeichnet sich durch

vereinzelt auftretende massive Beißaktionen aus, die vor allem auf einen Mangel an

Ressourcen zurückzuführen ist. Ein unzureichendes Tier-Fressplatzverhältnis kann

beispielsweise ein benachteiligtes Tier dazu verleiten, den Konkurrenten mittels auf den

Schwanz gerichteter Beißattacken vom Futtertrog zu vertreiben. Auch mangelnder

Liegekomfort ist möglicherweise eine der Ursachen für Frustration und daraus resultierendes

Schwanzbeißen (Widowski, 2002). Weitere Umweltstressoren wie zum Beispiel Mängel in

der Lüftungs- (Hitze-/ Kältestress) oder Fütterungstechnik können diese Form der

Verhaltensstörung provozieren. Mögliche Maßnahmen sind vor allem das Beheben der

jeweiligen Mängel.

„Obsessives Beißen“: Bei dieser Form des Schwanzbeißens handelt es sich um ein eher

seltener beobachtetes Fehlverhalten von einzelnen Individuen, welches als pathologischer

Wandel hin zu Stereotypien gewertet werden kann (Taylor et al., 2010). In diesem Fall richten

Einzeltiere Beißattacken gegen die Schwänze von Buchtengenossen und entfernen innerhalb

sehr kurzer Zeit die Hautschichten bis hin zur Amputation von Teilen oder des gesamten

Schwanzes. Über die Ursachen für diese Form der Verhaltensstörung ist wenig bekannt;

möglicherweise hat der individuelle Gesundheitsstatus des jeweiligen Tieres eine besondere

Bedeutung. Die sicherste Maßnahme zur Behebung dieses Fehlverhaltens ist eine Isolierung

des Täters, die auch dringend erforderlich ist, um die Gruppe vor weiteren Verletzungen zu

schützen (Taylor et al., 2010).

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Gesetzliche Grundlagen für das Schwanzkupieren bei Schweinen

Die EU Gesetzgebung (Richtlinie 2001/ 93/ EG, Anhang, Kapitel 1, Artikel 8) legt Folgendes

fest: „Ein Kupieren der Schwänze oder eine Verkleinerung der Eckzähne dürfen nicht

routinemäßig und nur dann durchgeführt werden, wenn nachgewiesen werden kann, dass

Verletzungen am Gesäuge der Sauen oder an den Ohren oder Schwänzen anderer Schweine

entstanden sind. Bevor solche Eingriffe vorgenommen werden, sind andere Maßnahmen zu

treffen, um Schwanzbeißen und andere Verhaltensstörungen zu vermeiden, wobei die

Unterbringung und Belegungsdichte zu berücksichtigen sind.“ Zu den europäischen Ländern,

in denen das Kupierverbot grundsätzlich strikt umgesetzt wird, zählen Finnland, Litauen

Norwegen, Schweden und die Schweiz. In diesen Ländern ist Kupieren nur in

Ausnahmefällen und nur mit einer Anästhesie erlaubt. Das deutsche Tierschutzgesetz

verbietet „[...] das vollständige oder teilweise Amputieren von Körperteilen […] eines

Wirbeltieres“ zwar auch, das Verbot gilt aber nicht, wenn der „Eingriff im Einzelfall nach

tierärztlicher Indikation geboten ist […]“ (TierSchG 2006, § 6, Absatz 1). Diese gesetzliche

Ausnahme wird in Deutschland zurzeit als Grundlage genutzt, um ein flächendeckendes

routinemäßiges Kürzen der Schwänze in der Praxis durchzuführen. Die Bundesländer

Nordrhein-Westfalen, Niedersachsen und Schleswig-Holstein haben spezielle Vereinbarungen

geschlossen, das routinemäßige Kupieren bis 2016/ 2017 zu unterbinden. Das Ministerium in

Niedersachsen hat in diesem Rahmen mit Hilfe des Europäischen Landwirtschaftsfonds für

die Entwicklung des ländlichen Raumes (ELER) die sogenannte „Ringelschwanzprämie“

eingeführt, um einen finanziellen Anreiz für die Umsetzung des Kupier-Verbotes zu setzen.

Die „Gemeinsamen Eckpunkte zur Tierwohlförderung“ sind neben dem Niedersächsischen

Landwirtschaftsministerium von der Interessengemeinschaft der Schweinehalter Deutschlands

(ISN) sowie vom Agrar- und Ernährungsforum Oldenburger Münsterland (AEF)

unterzeichnet worden (NMELV, 2015).

Effekt des Schwanzkupierens beim Schwein

Das Kupieren der Schwänze ist eine weitverbreitete präventive Maßnahme, die bei

Schwanzbeißen im Schweinebestand angewendet wird (Bracke et al., 2012). Als einer der

Gründe für den „Erfolg“ des Schwanzkupierens wird u. a. eine Hyperalgesie des

Amputationsstumpfes vermutet, die dazu führt, dass Schweine schneller abwehrend auf

12

Manipulationen am Schwanz reagieren (Simonsen et al., 1991). Die Wahrscheinlichkeit,

Opfer einer Beißattacke zu sein, stieg in einer Studie, die an 63 000 Schweinen auf sechs

Schlachthöfen in Großbritannien durchgeführt wurde, um den Faktor 2,73 an, wenn die

Schwänze nicht kupiert waren (Hunter et al., 1999). Di Martino et al. (2015) untersuchten den

Effekt des Kupierens auf das Tierwohl von Schweinen (4.-40. Lebenswoche), die nicht unter

optimalen Bedingungen gehalten wurden (Besatzdichte 0,32 m²/ Tier in der Ferkelaufzucht,

Vollspaltenboden, Probleme mit PRRS, Influenza und Actinobacillus pleuropneumoniae im

Bestand). Die nicht kupierten Tiere wiesen unter diesen Bedingungen zwar vermehrt

Schwanzverletzungen auf, das Tierwohl, welches anhand von Blutparametern,

Verhaltensbeobachtungen und Mortalitätsraten beurteilt wurde, war jedoch nicht generell

schlechter als in einer kupierten Kontrollgruppe. Darüber hinaus ist festzustellen, dass

Kupieren das Problem des Schwanzbeißens weder vollständig verhindern kann, noch die

eigentlichen Ursachen behebt (Nannoni et al., 2014). Gerade im Hinblick auf die aktuelle

Verbraucherdiskussion zum Thema Tierwohl in der Nutztierhaltung gehen die Bestrebungen

dahin, die Integrität des Tierkörpers zu erhalten und die Haltungsbedingungen für die Tiere

soweit zu optimieren, dass eine Haltung von Schweinen mit intakten Schwänzen unter

Praxisbedingungen möglich wird.

Mechanismen und Ursachen von Schwanzbeißen

Grundsätzlich verfügen Tiere über unterschiedliche und individuell ausgeprägte

Bewältigungsstrategien („Coping-Strategien“), um auf Anforderungen, z. B. aus ihrer

Haltungsumgebung zu reagieren. Bolhuis et al. (2005) untersuchten die individuellen

Anpassungsstrategien von Schweinen mit Hilfe eines sogenannten „Back-Tests“. Für den

„Back-Test“ werden die Tiere in einer speziellen Vorrichtung auf den Rücken gelegt und die

Anzahl der Fluchtversuche innerhalb einer Minute dokumentiert. Ein Schwein wurde als

„stark reagierend“ klassifiziert, wenn es mehr als vier Fluchtversuche in zwei Tests zeigte und

als „schwach reagierend“, wenn die Anzahl der Fluchtversuche in zwei Tests unter vier lag.

Die als „stark reagierend“ klassifizierten Tiere zeigten vermehrt aggressives Verhalten

(Kopfschläge, Beißen und Kämpfe) gegenüber Buchtengenossen, während die als “schwach

reagierend” klassifizierten Tiere vermehrt manipulatives Verhalten („belly nosing“, Ohren-

oder Schwanzbeißen) zeigten. Diese tierindividuellen Unterschiede sind ein möglicher

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Ansatzpunkt, warum Schwanzbeißen unregelmäßig und scheinbar keinem Muster folgend in

den Beständen auftritt. Dabei wird häufig geschildert, dass nur einzelne Buchten betroffen

sind und die Ursachen des jeweiligen Ausbruches schwer nachzuvollziehen sind.

Darüber hinaus besteht die Problematik vor allem in den multifaktoriellen Ursachen des

Geschehens. Jeder Stressor, sei er beispielsweise klimatischer, diätetischer oder

gruppendynamischer Ursache, kann die Tiere und deren physiologische Verhaltensmuster aus

dem Gleichgewicht bringen. Jeder Einflussfaktor hat einen additiven Effekt auf das

Gesamtrisiko und die zuletzt hinzugekommenen Stressoren können das sprichwörtliche „Fass

zum Überlaufen“ bringen. Der Risikofaktor, der dann als Auslöser für Schwanzbeißen im

Bestand gilt, muss – dem Modell folgend – dabei nicht unbedingt der mit dem höchsten

Einzelrisiko sein (EUWelNet, 2013). Im Folgenden werden die möglichen und häufig

diskutierten Ursachen des Schwanzbeißens erläutert und der Fokus besonders auf die

Faktoren Beschäftigungsmaterial und Absetzmanagement gelegt.

Anreicherung der Haltungsumgebung

Durch das europäische Recht (Richtlinie 2008/ 120/ EG, Anhang 1, Kapitel 1, allgemeine

Bedingungen § 4) ist festgelegt, dass Schweine ständigen Zugang zu ausreichenden Mengen

an Materialien haben müssen, die sie untersuchen und bewegen können, wie z. B. Stroh, Heu,

Holz, Sägemehl, Pilzkompost, Torf […]. Der Mangel an wühlbarem Substrat wurde bereits

als ein ausschlaggebendes Risiko für Schwanzbeißen identifiziert und die Motivation,

Erkundungsverhalten auszuüben, wird als eine der Hauptfaktoren für Schwanzbeißen

angesehen (EFSA, 2007). Dabei ist zu beachten, dass Schweine unter seminatürlichen

Bedingungen 75 % der Tagesaktivität mit Erkundungsverhalten und Futtersuche verbringen

(Stolba und Wood-Gush, 1989). Diese Verhaltensweisen können in der reizarmen Umgebung

von intensiven Haltungssystemen nur zu einem geringen Anteil ausgeübt werden. Wenn kein

passendes Beschäftigungsmaterial verfügbar ist, können Schweine ihr Suchverhalten auf

Buchtengenossen oder auf die Buchtenumgebung ausweiten (EFSA, 2007). Schweine in einer

reizarmen Haltung (untersucht in der 4., 7. und 18. Lebenswoche) manipulierten nachweislich

häufiger den Boden, die Wände und Buchtengenossen und zeigten häufiger Schwanzbeißen

als Schweine in einer angereicherten Haltung (Petersen et al., 1995). Das Angebot von

Pilzkompost bei konventionell gehaltenen Mastschweinen reduzierte z. B. die Umorientierung

14

von Wühlverhalten auf Buchtengenossen und verbesserte das Tierwohl zusätzlich aufgrund

des seltener vorkommenden Schwanzbeißens (Sneddon et al., 2001). Van de Weerd et al.

(2003) untersuchten 74 verschiedene Objekte zur Umweltanreicherung und betonten die

Bedeutung der Materialeigenschaften „kaubar“, „verformbar“ und „zerstörbar“. Demzufolge

ist die Manipulierbarkeit des Beschäftigungsmaterials für Schweine ein wichtiger Aspekt.

Dieses sollte dem Anspruch an ihr natürliches Futtersuchverhalten entsprechen, welches die

Erkundung der Umgebung mittels Wühlen, Schnüffeln, Beißen und Kauen umfasst (Studnitz

et al., 2007). Außerdem verringert eine Anreicherung der Umwelt die Zeit, in der die Tiere in

negatives Sozialverhalten und aggressive Verhaltensweisen involviert sind (Beattie et al.,

2000). Van de Weerd et al. (2006) verglichen verschiedene Maßnahmen zur Beschäftigung:

Strohautomat, Futterautomat, Tränkeautomat, mit Stroh eingestreuter Liegebereich und ein

kommerzielles Beschäftigungsobjekt („Bite Rite“). Der eingestreute Liegebereich war die

erfolgreichste Maßnahme, die Schweine zu beschäftigen und schweres Schwanzbeißen zu

verhindern, wohingegen in Gruppen, die nur mit zusätzlichen Tränkeautomaten und Bite Rite

ausgestattet waren, die höchste Prävalenz an Schwanzbeißen festzustellen war. Scott et al.

(2007) verglichen die Aktivitätslevel von Schweinen in unterschiedlich ausgestatteten

Buchten und stellten fest, dass sie sich deutlich länger mit Stroh als mit Plastikrohren

beschäftigten. Die Bereitstellung von Stroh reduzierte, ungeachtet der Faserlänge, das

Auftreten von Verhaltensweisen wie „nosing“ (Manipulation von Buchtengenossen über die

Schnauze), Aggression und Schwanzbeißen im Vergleich zu strohloser Haltung. Die

Prävalenz von Schwanzbeißen in Gruppen mit kurzfaserigem Stroh war jedoch höher als in

den Gruppen, denen langes oder nur teilweise gekürztes Stroh angeboten wurde (Day et al.,

2008). Amdi et al. (2015) untersuchten den Einfluss von Stroh, das in unterschiedlichen

Mengen (25 g/ 50 g/ 100 g/ Schwein/ Tag) und Häufigkeiten (1 x/ 2 x/ 4 x täglich) angeboten

wurde, auf das Auftreten von negativen, gegen Buchtengenossen gerichteten

Verhaltensweisen. Ein Unterschied zwischen diesen Versuchsgruppen konnte nicht

festgestellt werden. Zonderland et al. (2008) testeten vier verschiedene

Präventionsmaßnahmen (Kette, Reifen, Strohgabe über eine Raufe und auf den Boden) und

stellten fest, dass Schwanzbeißen am effektivsten mit einer kleinen Menge Stroh, das zweimal

täglich auf den Boden verabreicht wurde, zu verhindern war, während Strohraufe, Kette oder

Reifen einen geringeren und in dieser Reihenfolge abnehmenden präventiven Effekt hatten.

15

Eine auf zweimal pro Woche reduzierte Strohgabe konnte die Anzahl von

Schwanzbeißaktionen nicht signifikant reduzieren (Statham et al., 2011). Nach Day et al.

(2002) steigert das Umstallen von Schweinen aus einer eingestreuten in eine nicht

eingestreute Haltungsumgebung manipulative Verhaltensweisen gegen Buchtengenossen.

Diese Erkenntnis trägt zu der Annahme bei, dass Schweine, die an Beschäftigungsmaterial

gewöhnt sind, möglicherweise frustriert werden, wenn das Material nicht mehr zur Verfügung

steht. Munsterhjelm et al. (2009) verglichen Gruppen, die in früheren Lebensabschnitten

(Abferkelbereich und Aufzucht) Beschäftigungsmöglichkeiten zur Verfügung hatten, mit

Gruppen, die erst in späteren Lebensabschnitten zusätzliche Beschäftigung erfahren hatten.

Ein Mangel an Beschäftigung während der Mast führte zu erhöhten Schwanzverletzungen in

Gruppen, die bereits in den ersten Lebensphasen Beschäftigungsmaterial erhalten hatten. Eine

Anreicherung der Umwelt vor dem Absetzen kann somit Auswirkungen auf das

Schwanzbeißverhalten in späteren Lebensabschnitten haben (Oostindjer et al., 2010).

Saugferkel, die in konventionellen Abferkel-Systemen von der Geburt bis zum Absetzen

Zugang zu Seilen und Zeitungen hatten, übten weniger oro-nasale Manipulationen an anderen

Ferkeln aus, als die Ferkel der Kontrollgruppe, die ohne Beschäftigungsmaterial gehalten

wurden. Entsprechend hatten die Schweine aus der Gruppe mit Beschäftigungsmaterial

während der Säugezeit nach dem Absetzen weniger häufig schwere Schwanzverletzungen als

Schweine der Kontrollgruppe (Telkänranta et al., 2014). Die genannten Studien zeigen, dass

Beschäftigungsmaterial eine wichtige Rolle in der Prävention von Verletzungen durch

Schwanzbeißen spielt, da es den Tieren ermöglicht, eine größere Bandbreite ihres

Verhaltensrepertoires auszuleben. Allerdings muss beachtet werden, dass diese

Beschäftigungsmaterialien zumeist nicht zu den weitverbreiteten Vollspaltenböden und den

heutigen Güllesystemen in der konventionellen Schweinehaltung passen. Die Verwendung

von gekürztem Material, welches das Risiko verstopfter Leitungssysteme minimiert, könnte

ein möglicher Kompromiss sein.

Absetzmanagement

Eine weitere Besonderheit des Themas Schwanzbeißen ist der zeitliche Zusammenhang

zwischen dem Auftreten der Verhaltensstörung und dem Absetzen. In der zweiten Woche

nach dem Umstallen in die Ferkelaufzucht wurden bereits erste Schwanzverletzungen

16

beobachtet (Abriel and Jais, 2013; Veit et al., 2014). Schweine sind in den heutigen intensiven

Haltungsformen mit vielen Herausforderungen konfrontiert. Der wohl massivste Einschnitt in

das Leben eines Ferkels ist dabei das Absetzen, das mit der Trennung von der Muttersau, und

üblicherweise auch mit einer Änderung der Haltungsumgebung (sozial und räumlich), teils

sogar mit einem Transport einhergeht. Möglicherweise sind die Ferkel in den ersten Tagen

nach dem Absetzen mit dem Kennenlernen der neuen Umgebung und der Festlegung der

Rangordnung mit den Buchtengenossen beschäftigt. Fehlen anschließend

Beschäftigungsmöglichkeiten, kann die reizarme Umgebung zu Frustration bei den Tieren

führen und Schwanzbeißen auslösen, was wiederum den zeitlichen Bezug zum Absetzen

erklären könnte. Zusätzlich zu den damit verbundenen Stressoren findet bei dem Übergang

vom Abferkelbereich in die Ferkelaufzucht häufig auch eine mehr oder weniger abrupte

Futterumstellung statt, mit der die Ferkel konfrontiert sind. Unter natürlichen Bedingungen

erfolgt die Entwöhnung von der Muttermilch schrittweise über einen längeren Zeitraum, der

bis zu einem Alter von zehn bis zwölf Wochen noch nicht abgeschlossen ist (Lallès et al.,

2007). Außerdem entspricht das routinemäßig angewandte Sortieren der Würfe beim

Absetzen nach Größe und eventuell auch nach Geschlecht, nicht den natürlichen

Gegebenheiten in einer Rotte und erfordert von den Läufern das Festlegen einer neuen

Rangordnung mit wurffremden Artgenossen. Beim Mischen von zwei Würfen, zeigten die

Tiere ein gesteigertes agonistisches Verhalten und Erkundungsverhalten, hatten kürzere

Ruhephasen und wiesen einen höheren Anteil von schweren Hautläsionen auf (Hötzel et al.,

2011). Frühes Mischen von unbekannten Würfen während der Laktation reduzierte dagegen

agonistische Verhaltensweisen und Läsionen in den ersten zwei Tagen nach dem Absetzen

(Bohnenkamp et al., 2012). Stress durch das Mischen der Tiere gilt somit als möglicher

Auslöser für Schwanzbeißen unter konventionellen Bedingungen (EFSA, 2007). Von

Bedeutung scheint zudem auch die Haltung der Tiere vor dem Absetzen zu sein. Die

Sozialisierung von Ferkeln aus verschiedenen Würfen hatte Langzeiteffekte auf das

Sozialverhalten der Tiere, reduzierte sozialen Stress zum Absetzen und erhöhte den Zuwachs

in der nachfolgenden Aufzucht (D‘Eath et al., 2005; Kutzer et al., 2009). Schweine, die in

einem Gruppen-Abferkelungs-System aufwuchsen, waren weniger aggressiv und toleranter

gegenüber unbekannten Buchtengenossen als Schweine aus konventionellen

17

Abferkelungssystemen, in denen sich die Ferkel erst nach dem Absetzen erstmalig begegneten

(Li and Wang, 2011).

Einfluss weiterer Faktoren

Ein weiterer Faktor, der das Auftreten der Verhaltensstörung „Schwanzbeißen“ beeinflusst, ist

die Genetik. Breuer et al. (2003) untersuchten jeweils 100 Schweine von drei verschiedenen

Rassen (Large White, Landrasse und Duroc) individuell in einem „tail chew test“. Dazu

wurden den Tieren jeweils zwei Seile angeboten und die Dauer und Häufigkeit des Seil-

gerichteten Verhaltens über einen Zeitraum von zehn Minuten dokumentiert. Außerdem

wurde das Auftreten von negativem Sozialverhalten gegenüber Buchtengenossen nach dem

Absetzen in der Ferkelaufzucht erfasst. Die Rasse hatte einen signifikanten Effekt sowohl auf

die Intensität des Seil-gerichteten Verhaltens im „tail chew test“ als auch auf negatives

Sozialverhalten. Tiere der Rasse Duroc interagierten häufiger und länger mit dem

angebotenen Seil und zeigten auch häufiger gegen Buchtengenossen gerichtetes

Beißverhalten. In einer nachfolgenden Studie wurden klinische Beißer (295 aus 9018 Ferkel)

identifiziert und ihrer Abstammung zugeordnet (Breuer et al., 2005). Die Inzidenz für

Schwanzbeißen war dabei für Schweine der Rasse Large White geringer als für Landrasse.

Schwanzbeißen konnte für die Landrasse-Tiere als erblich festgestellt werden (h² = 0,27). In

anderen Untersuchungen wurde nachgewiesen, dass Schweine der Rasse Yorkshire häufiger

Opfer von Schwanzbeißen waren als Schweine der Landrasse. Die Häufigkeit des

Schwanzbeißens stieg mit zunehmendem Magerfleischanteil und abnehmender

Rückenspeckdicke an (Moinard et al., 2003; Sinisalo et al., 2012). Bei der Bewertung des

Effektes des Magerfleischanteils ist zu bedenken, dass aufgrund von Verbraucherinteressen in

den letzten Jahrzehnten in der Zucht verstärkt auf einen immer höheren Magerfleischanteil

selektiert wurde.

Ein weiterer Aspekt, der im Zusammenhang mit der Verhaltensstörung Schwanzbeißen

diskutiert werden sollte, ist das Geschlecht. In Untersuchungen an Schlachthöfen (Hunter et

al., 1999; Kritas and Morrison, 2007; Keeling et al., 2012) wurde festgestellt, dass männliche

Schweine eher Bissverletzungen aufwiesen als weibliche Schweine. Darüber hinaus wurden

Kastraten eher gebissen als Eber (Walker and Bilkei, 2006). Im Gegensatz dazu konnten

18

Sinisalo et al. (2012) keine signifikanten Unterschiede zwischen Ebern, weiblichen Tieren

und Kastraten im Risiko, Opfer von Schwanzbeißen zu werden, beobachten.

Neben dem Geschlecht hat auch die Gruppenzusammensetzung eine Bedeutung für das

Auftreten von Schwanzbeißen. Nach Schrøder-Petersen et al. (2004) ist die Häufigkeit von

„tail-in-mouth behaviour“ signifikant niedriger in rein männlichen Gruppen als in weiblichen

oder gemischt-geschlechtlichen Gruppen. In vergleichenden Untersuchungen konnte

festgestellt werden, dass weibliche Ferkel eher zu Schwanzbeißen neigen als männliche

(Zonderland et al., 2010). Außerdem wurden bei Tieren, die in gemischt-geschlechtlichen

Gruppen gehalten wurden, weniger häufig Schwanzverletzungen am Schlachthof registriert,

als in getrennt-geschlechtlichen Gruppen (Hunter et al., 2001). „Tail-in-mouth behaviour“ trat

hingegen in getrennt-geschlechtlichen Gruppen signifikant weniger häufig auf, als in

gemischt-geschlechtlichen (Schrøder-Petersen, et al., 2003). Im Gegensatz dazu konnten

Moinard et al. (2003) keinen Zusammenhang zwischen der Geschlechterverteilung und dem

Auftreten von Schwanzbeißen beobachten.

Neben den genannten biologischen Risikofaktoren gibt es auch einige Managementfaktoren,

die entscheidenden Einfluss auf das Schwanzbeißen haben können. Eine Belegdichte von

110 kg/ m² oder mehr während der Ferkelaufzucht und Mast erhöhte das Risiko für

Schwanzbeißen um den Faktor 2,7 (Moinard, et al., 2003). Andererseits haben Beattie et al.

(1996) eine Besatzdichte von 0,5, 1,1, 1,7 und 2,3 m² pro Schwein vergleichend untersucht

und vermuten, dass weniger die Größe der verfügbaren Fläche das Verhalten der Schweine

beeinflusst als die Ausgestaltung der Buchten. Nach Abriel und Jais (2013) waren die

Unterschiede in der Häufigkeit von Schwanzverletzungen zwischen angereicherten Buchten

mit normaler und reduzierter Besatzdichte gering. Rodenburg und Koene (2007) haben den

Einfluss der Gruppengröße auf negatives Sozialverhalten, Aggression, Angst und Stress bei

landwirtschaftlichen Nutztieren untersucht. Sie schlussfolgerten, dass es für eine Reduktion

der oben genannten Verhaltensweisen wichtig ist, eine komplexe Umgebung und separate

Funktionsräume zum Ausleben vielfältiger Verhaltensweisen zur Verfügung zu stellen. Nach

Schmolke et al. (2003) haben unterschiedliche Gruppengrößen (10, 20, 40 und 80 Tiere im

Vergleich) keinen Effekt auf das Auftreten von Schwanzbeißen.

19

In Bezug auf das Klima und die Lüftung sind die Ergebnisse eindeutiger. Seit Längerem ist

bekannt, dass erhöhte Ammoniakgehalte bei den Tieren Stress hervorrufen. Besonders in den

kritischen Wochen nach dem Absetzen wurden Aggressionen vermehrt bei Schweinen

beobachtet, die bei 20 vs. < 5 ppm Ammoniak und 40 vs. 200 Lux Lichteinstrahlung gehalten

wurden (Parker et al., 2010). Der Ammoniakgehalt der Versuchsgruppe erreicht hierbei die

gesetzlich festgelegte Obergrenze, während die Lichteinstrahlung die gesetzlich

vorgeschriebenen Bedingungen um die Hälfte unterschreitet (TierSchNutztV, 2006, Abschnitt

5, § 26). Daraus ist allerdings nicht abzuleiten, dass ein Gehalt von 20 ppm Ammoniak

toleriert wird und allein die unzureichende Lichtstärke die Aggressionen induziert hat. Mit

Hilfe des „husbandry advisory tools“ wurde vielmehr herausgestellt, dass die Kategorie Klima

und Umgebung (Temperatur, Feuchtigkeit, Züge, aversive Faktoren in der Atmosphäre z. B.

Ammoniak/ Staub im Liegebereich) den wichtigsten Risikofaktor für Schwanzbeißen bei

Mastschweinen in konventionellen Betrieben darstellt (Taylor et al., 2012).

Ein weiteres Thema, das in Bezug auf Schwanzbeißen Erwähnung finden muss, ist die

Fütterung. Wie bereits angesprochen, ist ein ausreichendes Tier-Fressplatzverhältnis

entscheidend für eine stressfreie Nahrungsaufnahme, die allen Tieren zur gleichen Zeit

ermöglicht werden sollte (Hansen et al., 1982). Die Nutzung eines Fütterungssystems mit fünf

oder mehr Schweinen pro Fressplatz erhöhte das Risiko für Schwanzbeißen (Moinard et al.,

2003). Schweine können über das Erkundungsverhalten ernährungsphysiologische

Information gewinnen und über diesen Ernährungs-Feedback das Futteraufnahmeverhalten

dahingehend verändern, dass diätetische Defizite korrigiert werden (Jensen et al. 1993; Day et

al., 1996). Beattie et al. (2005) vermuteten weitergehend, dass Schweine, die Schwanzbeißen

zeigen, ernährungsphysiologische Defizite aufweisen, was zu einem intensiveren

Erkundungsverhalten in Form von fortgesetztem „Bekauen“ der Buchtgenossen führt. Anhand

histologischer Untersuchungen des Darms von Tieren in einer Bucht, in der Schwanzbeißen

auftrat, konnten verkürzte Dünndarmzotten und darüber hinaus geringere

Plasmakonzentrationen an Aminosäuren bei den Opfern von Schwanzbeißen nachgewiesen

werden (Palander et al., 2013). Mögliche Erklärungen hierfür sind eine verringerte

Absorptionskapazität, ein geändertes Fressverhalten oder eben Umweltstress infolge

Schwanzbeißens. Einen weiteren Einfluss auf das Auftreten von Schwanzbeißen hat die

Zusammensetzung der Ration. Hohe Rohfasergehalte in der Ration reduzieren fehlgeleitetes

20

Erkundungsverhalten (Brouns et al., 1994), eine mögliche Erklärung hierfür ist ein länger

anhaltendes Sättigungsgefühl. Außerdem wurde vermehrt Schwanzbeißen beobachtet, wenn

Schweine eine proteinarme Ration im Gegensatz zu einer adäquaten Proteinversorgung

erhalten (BPEX, 2005). Ein Faktor, der weitergehend untersucht werden sollte, ist das

zeitliche Fütterungsregime. Schweine, die ad libitum gefüttert wurden, erkundeten angebotene

Beschäftigungsmaterialien weniger häufig als restriktiv gefütterte Tiere (Zwicker et al., 2013).

Neben der Fütterung ist ein guter Gesundheitszustand zur Vermeidung von Schwanzbeißen

von entscheidender Bedeutung (Moinard et al., 2003; Walker and Bilkei, 2006). Das

Auftreten von respiratorischen Erkrankungen ist mit einer 1,6-fachen Steigerung des Risikos

für Schwanzbeißen assoziiert (Moinard, et al., 2003). Schweine, die erkrankt sind, sind

zurückhaltender in der Abwehr von Beißern und unfähig, sich zu verteidigen (Kritas and

Morrison, 2004). Außerdem haben erkrankte Tiere geringere Wachstumsraten, was

abnehmende Chancen reflektiert, sich im Kampf um Ressourcen gegen Buchtengenossen

durchzusetzen, was wiederum Schwanzbeißen auslösen kann (Taylor, et al., 2010).

Indikatoren

Videobeobachtungen auf Einzeltierbasis liefern Erkenntnisse zum individuellen Verhalten der

Schweine. Nach Zonderland et al. (2010) steigen, unabhängig vom Schweinetyp, Unruhe und

die Häufigkeit der Beißaktivitäten in den Tagen vor einem Schwanzbeißausbruch an. Als

Ausbruch wurde dabei der Tag definiert, an dem mindestens ein Ferkel eine tiefergehende

Wunde am Schwanz aufwies, beziehungsweise bei mindestens zwei Ferkeln oberflächliche

Kratzwunden an den Schwänzen beobachtet wurden. Die Erfassung der Inzidenz des „tail-in-

mouth behaviour“ lieferte bereits sechs Tage bevor die ersten Schwanzverletzungen in einer

Bucht auftraten Hinweise auf Tiere, die später zu ausgeprägten Beißern wurden (Zonderland

et al., 2011).

Die Messung des Aktivitätsverhaltens ist ein vielversprechendes Instrument, um den

Ausbruch von Schwanzbeißen vorherzusagen (Statham et al., 2009). Die retrospektive

Auswertung des Aktivitätsniveaus war in Gruppen, in denen vier Tage später ein Ausbruch

stattgefunden hat, signifikant höher, als in den Kontrollgruppen. In Übereinstimmung damit

wurde eine höhere Aktivität und ein gesteigertes manipulatives Verhalten gegenüber

21

Buchtengenossen und -umgebung dort beobachtet, wo Schwanzbeißen auftrat (Ursinus et al.,

2014). Außerdem konnte Schwanzbeißen mit anderen manipulativen Verhaltensweisen, wie

zum Beispiel Ohrenbeißen und „nosing“ in der Genital- und Bauchregion, in Verbindung

gesetzt werden (Beattie, et al., 2005).

Neben dem Aktivitätsverhalten ist auch die Schwanzhaltung der Tiere ein interessanter

Indikator. Als Zeichen der Domestikation besitzen die heutigen Schweinerassen einen

Ringelschwanz; dieser dient der Kommunikation und drückt möglicherweise den mentalen

Zustand der Tiere aus (Groffen, 2012). McGlone et al. (1990) beobachteten in ihrer Studie,

dass Schweine bei wiederholten Schwanzbeißausbrüchen ihre Schwanzhaltung änderten. Die

Autoren sehen diese Veränderung als Angstreaktion und vermuten, dass ein Einklemmen des

Schwanzes möglicherweise Schutz vor Beißern bietet. In Übereinstimmung damit wurde

beobachtet, dass in Gruppen ohne Schwanzbeißausbruch weniger Schweine ihre Schwänze

„zwischen die Beine geklemmt“ hatten (Statham, et al., 2009). Zonderland et al. (2009)

schlussfolgerten, dass die Schwanzhaltung der Schweine mit Manipulationen am Schwanz

zusammenhängt, und dass auffällige Verletzungen anhand der Schwanzhaltung zwei bis drei

Tage im Voraus vorhergesagt werden können.

Schlussfolgerungen

Die Schwierigkeit im Umgang mit dem Thema Schwanzbeißen liegt vor allem in den

multifaktoriellen Ursachen des Geschehens. Eine sichere Vermeidung der Verhaltensstörung

bei der Aufzucht unkupierter Tiere in der intensiven Nutztierhaltung ist durch einen einzelnen

Lösungsansatz nicht möglich. Vielmehr braucht jeder Betrieb eine eigene Strategie und vor

allem Erfahrungswerte in der Bekämpfung der Verhaltensstörung, da jedes System

unterschiedliche Einflussfaktoren hat, auf die individuell reagiert werden muss. Dabei stehen

neben optimalem Management und einer guten Tiergesundheit vor allem eine intensive

Tierbeobachtung und sofortige Intervention beim Auftreten von Schwanzbeißen im

Vordergrund (Veit, et al., 2014). Die Verhaltensstörung Schwanzbeißen drückt eine

Überforderung der Anpassungsfähigkeit der Tiere in intensiven Haltungsbedingungen aus.

Diese müssen dahingehend verändert werden, dass den Schweinen ein Ausleben der

angeborenen Verhaltensweisen ermöglicht wird. Eine wichtige Maßnahme zur Befriedigung

des Wühl- und Erkundungsverhaltens ist das Angebot von organischem

22

Beschäftigungsmaterial. Außerdem sollten weitergehende Untersuchungen den Fokus vom

Opfertier auf das Tätertier lenken und tierindividuelle Defizite analysieren, um der

Verhaltensstörung auf den Grund zu gehen.

Quellen

2001/ 93/ EG. Richtlinie 2001/ 93/ EG der Kommission vom 9. November 2001 zur

Änderung der Richtlinie 91/ 630/ EWG über Mindestanforderungen für den Schutz

von Schweinen.

2008/ 120/ EG. Richtlinie des Rates 2008/ 120/ EG vom 18. Dezember 2008 über

Mindestanforderungen für den Schutz von Schweinen.



Amdi, C. et al. 2015. Pen-mate directed behaviour in ad libitum fed pigs given different

quantities and frequencies of straw. Livestock Science 171: 44-51.

Beattie, V. E. et al. 2005. Factors identifying pigs predisposed to tail biting. Animal Science

80: 307-312.




Beattie, V. E., N. Walker, and I. A. Sneddon. 1996. An investigation of the effect of

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29

MATERIAL AND METHODS

Data collection

Data collection was carried out on the research farm of the Chamber of Agriculture of

Schleswig-Holstein (Futterkamp), Germany, between September 2013 and April 2014.

In the environmental enrichment study, 721 crossbreed piglets (Pietrain x (Large White x

Landrace)) from 60 litters were used in ten batches. Each batch corresponded to a farrowing

week. The piglets had an average birth weight of 1.4 ± 0.3 kg. The suckling period took place

in conventional farrowing systems (5.2 m² per pen), tails were not docked and males were not

castrated. From the second week of life until weaning, the piglets received a pre-starter diet

(14.6 MJ ME, 17.5 % protein, 1.45 % lysine, 0.25 % sodium). The piglets were weaned with

on average 28 days with an average weight of 8.0 ± 1.7 kg. Rearing lasted for 40 days until an

average weight of 25.4 ± 2.3 kg. The piglets were housed in mixed gender groups consisting

of one or two litters (12 or 24 piglets per pen) with an average space allowance of 0.38 or

0.42 m² per animal. According to the units the feeding system was either mash or dry feed ad

libitum with an animal to feeding place ratio of 2:1. For the first two weeks of rearing, the

piglets received a starter diet (14.4 MJ ME, 18.0 % protein, 1.40 % lysine, 0.20 % sodium),

thereafter the diet was gradually changed over the next four days and fed until day 40 of

rearing (13.4 MJ ME, 17.0 % protein, 1.30 % lysine, 0.25 % sodium). The drinking system

consisted of nipples and bowls, the floor was fully slatted and no bedding material was

offered. Plastic sticks, plastic balls and hard wooden sticks were provided as enrichment

material. The environmental temperature during rearing was automatically regulated by

forced ventilation. It was set at 29.5 °C on day one and decreased stepwise until 22.0 °C on

day 40. The animals had full artificial lighting between 06:00 h and 18:00 h.

In the weaning management study, 478 crossbreed piglets (Pietrain x (Large White x

Landrace)) from 40 litters were used in five batches. Tails were not docked and males were

not castrated. The piglets were weaned with on average 28 days with an average weaning

weight of 8.3 ± 1.6 kg. Five identical rearing units consisting of eight pens each were

consecutively used. Rearing lasted for 40 days in mixed gender groups until an average

weight of 25.9 ± 3.8 kg. The groups consisted of 12 piglets per pen with a space allowance of

0.38 m²/ animal. The feeding system used was mash feed ad libitum with an animal to feeding

30

place ratio of 2:1 and a diet composition of 17.0 % protein, 1.3 % lysine, 0.7 % calcium and

0.25 % sodium (13.4 MJ ME). Water was accessible through nipple drinkers. The floor was

fully slatted and no bedding material was provided. One plastic ball per pen (suspended on a

metal chain) and alfalfa hay in plastic bowls (one per pen, Ø 40 cm, animal to occupation

place ratio 1.2:1) was provided as environmental enrichment material. The environmental

temperature was automatically regulated by forced ventilation. It was set at 28.0 °C on day

one of rearing and decreased stepwise until 24.0 °C on day 40. The animals had full artificial

lighting between 06:00 h and 19:00 h.

Experimental design

In the environmental enrichment study, 721 piglets were divided randomly into three groups

litter-wise: a control group (CG) with 231 long-tailed piglets (♂ 121, ♀ 110), housed without

raw material, a dried corn silage group (SG, ♂ 124, ♀ 121) and an alfalfa hay group (AG,

♂ 117, ♀ 128) with 245 long-tailed piglets each. In the farrowing units, 20 litters were used

for each treatment, two litters of each treatment group (n = 3) per batch (n = 10) respectively.

After weaning, the piglets were housed either litter-wise or two litters were mixed, resulting

in 14 pens for each treatment with two different group sizes in the rearing units (12 or 24

piglets per pen). Within each of the ten batches, the number of CG, SG, and AG pens was

balanced and the locations of the treatment groups within the units were randomised.

In the weaning management study, 478 piglets were divided randomly into two groups, 240

piglets (♂ 124, ♀ 116) were housed in litter groups (LG), whereas 238 piglets (♂ 117, ♀ 121)

were mixed from at least three different litters (MG). Each unit consisted of four pens with

LGs and four pens with MGs, resulting in 20 pens for each treatment. The locations of the

treatment groups within the unit were randomised.

Treatments

In the environmental enrichment study raw material was provided twice a day (in the morning

and in the afternoon) from the second week of life until the end of rearing in the piglet nest

(Fig. 1) or in a piglet bowl (Fig. 2). During rearing the animal to occupation place ratio was

either 1.2:1 (12 piglets/ pen) or 2.4:1 (24 piglets/ pen). The amount of dried corn silage

offered per day and pen was about 100 g, the amount of alfalfa hay about 120 g/ day/ pen,

31

which corresponds to a handful of material per offer. In pens affected by tail-biting, the

intervention scheme was a jute bag (fixed on the pen wall), long, chopped straw on the pen

floor, grass silage or straw-peat mixture provided in piglet bowls. In severe cases, identified

biters were removed from the pen. Treatment with intervention material was also applied in

CG pens if an outbreak occurred.

Figure 1: Raw material treatment (AG)

in piglet nest (farrowing). Figure 2: Raw material treatment (AG) in

piglet bowl (Ø 40 cm, rearing)

Scoring

Tail lesions were scored weekly during farrowing (environmental enrichment study only) and

rearing. The scoring scheme (modified from Abriel and Jais, 2013) classifies the severity of

tail lesions with a four-point score consisting of “no visible damage“, “scratches, light bite

marks“, “moderate damage” (Fig. 3) and “severe damage” (Fig. 4). A tail-biting outbreak was

defined as an instance where at least one piglet showed a freshly bleeding tail wound or a loss

of the tail. Tail losses were classified by “original length of tail”, “loss of tail tip” (Fig. 5),

“partial loss” (Fig. 6) and “total loss” (Fig. 6). Furthermore, the gender and the size of the

animals (small, medium, large, in relation to pen mates) were recorded.

32

Figure 3: Moderate damage

Figure 4: Severe damage

Figure 5: Loss of tail tip Figure 6: Partial losses in the back and total losses in the front

Weight gain

In the environmental enrichment study, weight was collected at pen level (n = 27) at the

beginning and end of rearing. In the weaning management study, individual body weights of

the piglets (n = 478) were collected at weaning, at day 16 and at day 40 of rearing.

Video surveillance

In the environmental enrichment study, three farrowing units and three rearing units were

equipped with colour cameras (Santec, VTC-249IRP/ W or VTC-279IRPWD). In total, 99

piglets during farrowing (five pens of AGs, three pens of SGs) and 188 piglets during rearing

(four pens for each treatment group) were video recorded 24 hours every day (Fig. 7). The

HeitelPlayer software (Xtralis Headquarter D-A-CH, HeiTel Digital Video GmbH, Kiel,

33

Germany) was used to watch the videos. Six different behavioural patterns during farrowing

and ten different behavioural patterns during rearing were coded (Tab. 1). The time budgets of

each animal were investigated by instantaneous scan sampling with a 10 min interval from

06:00 h to 18:00 h. Additionally, a one-minute sampling interval was used for the first 10

minutes after raw material provision to determine the number of piglets occupied by the

material.

In the weaning management study, 32 pens (four units) were equipped with colour cameras

and recorded 24 hours per day (Santec, VTC-249/ IRP/ W or VTC-279/ IRPWD). The piglets

were individually marked with colour spray three times per week (Fig. 8). The open source

software BORIS (Friard, 2014) was used for the video analysis of five pens (three MGs, two

LGs). In total 60 piglets (♂ 29, ♀ 31) were analysed regarding five days prior to a scored tail-

biting outbreak and on the day of an outbreak itself. Eleven different behavioural patterns

were coded (Tab. 2).

Figure 7: Video observation in the

environmental enrichment

study (farrowing).

Figure 8: Video observation in the

weaning management study

(rearing).

34

Table 1: Ethogram used for video observation in the environmental enrichment study.

Behaviour Description

Lying Lying on the side or ventrally

Sitting Body supported by hind-quarters and stretched front legs

Standing Body supported by four stretched legs, includes locomotion

Feeding Head positioned in the feeder

Occupation with raw material Sniffing, nosing or rooting the raw material in piglet bowl/ nest

Occupation with toys Head on the toys

Additionally observed during

rearing

Tail exploration

Head on the back side of a pen mate, includes tail-in-mouth and tail-biting behaviour

Drinking Head on the water nipple

Belly nosing Manipulation of the abdomen of a lying pen mate

Occupation with intervention material

Head on the additional offered material (in case of tail-biting outbreaks)

35

Table 2: Ethogram used for video observation in the weaning management study.

Behavioural pattern Description

Instantaneous scan sampling


Standing Body supported by four stretched legs, includes locomotion


Occupation with raw material Sniffing, nosing or rooting the raw material in piglet bowl

Pen investigation Head on the pen surrounding (floor and walls)

Continuously collected

Tail exploration

• Performer Head on the tail of a pen mate, includes tail-in-mouth and tail-biting behaviour

• Receiver Being manipulated by a pen mate on the tail, includes tail-in-mouth and tail-biting behaviour

Belly nosing

• Performer Manipulation of the abdomen of a lying pen mate

• Receiver Being manipulated by a pen mate on the abdomen, while lying

Nosing

• Performer Snout contact with any part of the body of a pen mate except the belly region

• Receiver Being contacted by snout on any part of the body, except the belly region

36

The time budgets of each animal were investigated by instantaneous scan sampling over 20

minutes from every second hour between 06:00 h and 18:00 h (06:00 h to 06:20 h, 08:00 h to

08:20 h, 10:00 h to 10:20 h, 12:00 h to 12:20 h, 14:00 h to 14:20 h, 16:00 h to 16:20 h and

18:00 h to 18:20 h), the sampling scheme was every 2 minutes. Every 20 min interval is

counted as a scan, resulting in 42 scans per pen over six days, respectively 210 scans in total.

Due to technical difficulties, there was a lack of 17 scans, thus, the data was limited to 193

scans. Additionally, the manipulative behavioural patterns tail exploration (te), belly nosing

(bn) and nosing (no) were recorded continuously over the above-mentioned time frame to

determine the receivers (R) and performers (P) of each behaviour. In order to make piglets’

behaviour comparable and classifiable, the frequencies of the recorded manipulative

behavioural patterns required a conversion into scores/ indices. The character score (CS) was

developed to assign a number to each piglet (i), defining it as a receiver or performer by

changing the algebraic sign. The following formula defines CS, where x ∈ {te, bn, no}, y ∈

{1, 2, 3, 4, 5} and i ∈ {1,…,60}:

CSx,y (i) = [Px(i)/ max_Px,y] - [Rx(i)/ max_Rx,y] (1)

Px(i) is the number of manipulative contacts as a performer of behaviour x for piglet i and

max_Px,y is the maximum number of manipulative performer contacts in pen y. Rx(i) is the

number of manipulative contacts as a receiver of behaviour x for piglet i and max_Rx,y is the

maximum number of manipulative contacts as a receiver in pen y. CS ranges between -1

(absolute receiver) and +1 (absolute performer);

In order to determine ranges (upper limit (UL) and lower limit (LL)) for CS to assign piglets

to different character categories, the following formulas were used:

ULx,y = MWx,y + 0.52 x std x,y (2)

LLx,y = MWx,y – 0.52 x std x,y (3)

MWx,y denote the mean and std x,y denote the standard deviation of CS x,y. The constant 0.52 is

the 70 %-quantile of the standard normal distribution. Piglets with CSs within the range of UL

and LL were named as “neutral”. Piglets with CSs which exceeded the UL were named as

“performer” and piglets with CSs which fell below the LL were named as “receiver”.

37

Statistical procedures

The software package SAS 9.2® was used for statistical analysis (SAS, 2008). The fit

statistics AICC “Akaike’s information criterion corrected” (Hurvich and Tsai, 1989) and the

BIC “Bayesian information criterion” (Schwarz, 1978) were used to evaluate the fitting of the

models. Fixed effects were added stepwise to the models. The model with the smallest AICC

and BIC was chosen for the analysis.

Environmental enrichment study

The data of tail lesions and tail losses followed a multinomial distribution (Score 0-3).

Therefore, the procedure GLIMMIX was used assuming a cumulative logit link function for

the multinomial distributed data. Due to the fact that tail-biting did not occur during

farrowing, the data for the statistical analysis was limited to the rearing period. The

experimental unit was the pen. The fixed effects group (CG, SG, AG), batch (1-10), week

after weaning (1-6) and the interaction of group and batch were used in the final model for tail

lesions. The pen (nested in batch) was included as a random effect. Only the last observation

at the end of rearing was taken into consideration regarding tail losses. The group (CG, SG,

AG) and the batch (1-10) were used as fixed effects in the final model for tail losses.

The MIXED procedure was used in order to estimate the effect of tail-biting on total weight

gain during rearing. For every treatment group and scoring scheme (tail lesions and tail

losses) nine pens were ranked regarding the total number of piglets with a score higher than

Score 0 within each pen, resulting in three pens for a low, respectively medium and high level

of tail lesions and tail losses (only last observation was taken into consideration). The level of

tail lesions/ tail losses (low, medium, high), the treatment group (CG, SG, AG) and the

interaction between level of tail lesions/ tail losses and treatment group were used as fixed

effects. Significant differences in the least-square-means were adjusted with the Bonferroni-

correction (p < 0.05) (Westfall et al., 2011).

The trait occupation with the raw material provided was investigated with two models

(farrowing, rearing). Occupation was coded as a binary trait (0: not occupied, 1: occupied).

The procedure GLIMMIX was used with the link function logit. The fixed effects group (SG,

AG), batch (1-3), day after first raw material provision (1-16) and the interaction between

group and day after first raw material provision were used in the final model for farrowing.

38

The fixed effects group (SG, AG), batch (1-3), day after weaning (1-28) and the interaction

between group and day after weaning were used in the final model for rearing. The pen

(nested within batch) was included as a random effect in both models.

The trait activity behaviour was analysed with one model. Due to the low frequencies of the

behavioural patterns occupation with raw material and toys, tail exploration, drinking and

belly nosing, they were summarised as “active”, together with sitting, standing and feeding.

Lying behaviour was counted as “inactive” in further analysis. The activity behaviour was

coded as a binary trait, the procedure GLIMMIX was used with the link function logit. The

fixed effects group (CG, SG, AG), batch (1-3), day after weaning (1-28), daytime (6-18h), the

interaction of group and day after weaning, as well as the interaction of batch and day after

weaning were used in the final model. The pen was included as a random effect.

Weaning management study

The data of tail lesions and tail losses followed a multinomial distribution (Scores 0-3). Thus,

the GLIMMIX procedure was used assuming a cumulative logit link function for the

multinomial distributed data. The fixed effects treatment group (LG, MG), week after

weaning (1-6), batch (1-5) and the interaction of treatment group and batch were added

stepwise and used as fixed effects in the final model for tail lesions. The piglet was included

as a random effect and was nested within group and batch. The database was limited to the

last observation at the end of rearing regarding tail losses. The fixed effects group (LG, MG)

and batch (1-5) and the interaction of group and batch were used as fixed effects in the final

model for tail losses.

In order to estimate the effect of tail-biting on daily weight gain the MIXED procedure was

used. Daily weight gain of three time periods was analysed: weaning to day 16 (period 1), day

16 to day 40 (period 2) and weaning to day 40 (period 3). The scores of tail lesions on day 16

and day 40, as well as the scores of tail losses on day 40 of rearing were classified by

distribution: class 0 (0), class 1 (1) and class 2 (2, 3) for tail lesions, as well as class 0 (0) and

class 1 (1, 2, 3) for tail losses. Low frequencies of tail losses in the study did not allow the

distinction into three classes, which may confound the gradations. Classes of tail lesions (0, 1,

2) on day 16 were added as fixed effects to the model for period 1, whereas classes of tail

lesions and tail losses on day 40 were added as fixed effects to the model for period 2 and

39

period 3. Period 1 was not analysed for tail losses, because they were observed not until four

weeks after weaning. The treatment group (MG, LG), the batch (1-5), the interaction of group

and batch and the gender were used as fixed effects in all models. Weaning weight was added

as covariable to the final models. Significant differences in the least-square-means were

adjusted with the Bonferroni-correction (p < 0.05) (Westfall et al., 2011).

Video data was limited to five pens, because continuously observation of manipulative

behavioural patterns required a high time effort due to the required assignment of performer

and receiver of each interaction. Therefore, the treatment groups (LGs, MGs) were not

considered in further statistical analysis. The count data of the continuously observed

manipulative behavioural patterns was analysed using the GLIMMIX procedure with a

Poisson-distribution. The fixed effects day (- 5, - 4, - 3, - 2, - 1, 0), daytime (6, 8, 10, 12, 14,

16, 18) and pen (1-5) were used in the models for tail exploration, belly nosing and nosing.

The piglet (nested within pen) was added as a random effect to the final models. The

accumulated frequencies of the behaviours lying, standing and feeding, which were observed

by instantaneous scan sampling of each piglet over six days (every 20 min of every second

hour from 06.00 h to 18.00 h), were analysed using the MIXED procedure. The behaviours

pen investigation and occupation with provided material were rarely shown by the piglets,

thus, not considered in further statistical analysis. Three different models were used to test the

effect of character (calculated by formulas 1 to 3) separately for tail exploration, belly nosing

and nosing. The character of the piglets (performer, neutral, receiver) for the respective

manipulative behavioural pattern and the pen (1-5) were used as fixed effects in the models

for lying, standing and feeding behaviour. Daily weight gain was added as a covariable to the

final models. The gender was removed from the models due to low improvements of the

fitting and no significant impact. Significant differences in the least-square-means were


40

References



Friard, O. 2014. Behavioral observation research interactive software.

http://penelope.unito.it/boris/.

Hurvich, C. M., and C.-L. Tsai. 1989. Regression and time series model selection in small

samples. Biometrika 76: 297-307.

SAS. 2008. SAS Institute Inc. Cary, NC, USA.

Schwarz, G. 1978. Estimating the dimension of a model. The annals of statistics 6.2: 461-464.

Westfall, P. H., R. D. Tobias, and R. D. Wolfinger. 2011. Multiple comparisons and multiple

tests using SAS. SAS Institute.

41

CHAPTER ONE

Influence of raw material on the occurrence of tail-biting in undocked pigs

Christina Veit1, Imke Traulsen1, Mario Hasler2, Karl-Heinz Tölle3, Onno Burfeind4, Elisabeth

grosse Beilage5, Joachim Krieter1

1Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Kiel, Germany

2Discipline for Variance Statistics, Christian-Albrechts-University, Kiel, Germany

3ISN-Projekt GmbH, Damme, Germany

4Chamber of Agriculture, Schleswig-Holstein, LVZ Futterkamp, Blekendorf, Germany

5Field Station for Epidemiology, University of Veterinary Medicine, Hannover, Germany

Published in Livestock Science 191, 125-131

42

Abstract

The aim of this study was to reveal the effects of raw material provision on tail-biting

outbreaks in long-tailed pigs. Two different substrates, dried corn silage (SG, n = 245) and

alfalfa hay (AG, n = 245) were provided for the pigs twice per day from the second week of

life until the end of rearing. The control of long-tailed pigs (CG, n = 231) were kept without

the provision of additional raw material. Each tail was scored regarding tail lesions/tail losses

once per week with a four-point score (0 = no damage/original length, 3 = severe

damage/total loss). Weight was collected at the beginning and at the end of rearing. The effect

of week after weaning, the batch and the interaction between treatment group and batch had

highly significant influences on tail lesions (p < 0.001). The main concentration of

behavioural disorder took place in the rearing phase. Tail-biting started on average two to

three weeks after weaning, followed by tail losses one to two weeks later. The effect of batch

had a highly significant influence on tail losses at the end of rearing (p < 0.001). The number

of tail losses decreased with the number of batches and ranged from 98.6 % in batch one to

8.5 % in batch ten. This can be explained by enhanced and more precise animal observation

by stable staff and points out the learning process in the course of the study. At the end of

rearing, piglets of all batches had lost their tails to the greatest extent in CGs (48.7 %),

followed by AGs (45.2 %) and SGs (41.3 %). There was no clear trend in total weight gain

regarding the level of tail lesions and tail losses. Corn silage stayed attractive for the piglets

during the whole observation period, whereas the acceptance of the alfalfa hay decreased

towards the end of rearing. The daytime, the batch and the day after weaning, as well as the

interaction between treatment group and day after weaning had highly significant influences

on the overall activity behaviour during rearing (p < 0.001). To summarise, the rearing of

long-tailed pigs requires intensive animal observation and direct intervention in case of tail-

biting outbreaks. A provision of raw material on the floor of the piglet nest (suckling period)

and in a piglet bowl (rearing period) from the second week of life until the end of rearing

cannot prevent tail-biting during rearing, but reduces the occurrence of the behavioural

disorder in long-tailed pigs.

Keywords: Pigs; Environmental enrichment; Tail-biting; Animal welfare; Video observation.

43

1. Introduction

Tail-biting in pigs is a welfare concern in intensive pig husbandry and leads to economic

losses (EFSA, 2007). The multifactorial background makes it difficult to deal with the

problem. Higher stocking densities and deficiencies in feed quality or accessibility (Moinard

et al., 2003), poor ventilation (Hunter et al., 2001) as well as a lack of rooting substrate

(Zonderland et al., 2008) have been identified as environmental risk factors. On the biological

side, poor health (Day et al., 2002), breed (Breuer et al., 2003) and gender (Zonderland et al.,

2010a) could also play a role. The pigs’ need to perform exploration and foraging behaviour

is considered to be a major underlying motivation for tail-biting (EFSA, 2007). It should be

considered that pigs in the wild spend more than 70 % of their daily activity with these

behavioural patterns, which can be expressed only to a minor extent in the barren conditions

of intensive housing systems. When suitable material is unavailable, pigs may redirect their

search behaviour towards other pigs and the pen’s surroundings (EFSA, 2007). In accordance

with the EU Directive (2008/120/EG), pigs must have permanent access to a sufficient

quantity of material such as straw, hay, wood, sawdust, mushroom compost or peat to enable

proper investigation and manipulation activities. However, under practical conditions in

Germany, environmental enrichment is mainly limited to plastic toys or metal chains; even

though the absence of particulate, rootable substrate has already been identified as a

significant hazard leading to tail-biting (EFSA, 2007).

Tail-biting as a form of cannibalism is not a new phenomenon. Since the intensification of pig

production in the 1950s, it has turned out to be a problem and until now tail-docking has been

the most efficient way to avoid it. Under common intensive farming conditions, tail-docking

reduces the frequency of tail-biting, but does not completely eliminate the problem when

unfavourable conditions persist (EFSA, 2007). However, European law (2001/93/EG)

prohibits the routine docking of pig tails and it is realised under practical conditions using

veterinary case permissions. In order to turn away from this procedure towards the integrity of

the animals’ body and improvements in animal welfare, there is a need for intensive research

into docking alternatives. An important approach to minimise the risk for tail-biting is the

offer of manipulable material (Zonderland et al., 2008). It has been proved that environmental

enrichment reduces time spent involved in harmful social and aggressive behaviour (Beattie et

al., 2000). Several studies have shown a reduction in tail-biting behaviour through

44

environmental enrichment with straw (Van de Weerd et al., 2006; Day et al., 2008) or other

material which can to be rooted by the animals (Sneddon et al., 2001). These studies focused

on the observation of pigs in fattening units, whereas recent studies have shown that

behavioural disorder among long-tailed pigs occurs in rearing units (Abriel and Jais, 2013).

Furthermore, it has been pointed out recently that pre-weaning enrichment could have effects

on tail-biting behaviour in later life (Oostindjer et al., 2010; Telkänranta et al., 2014 ). The

aim of this study was to reveal the effects of raw material provision from the second week of

life until the end of rearing on the occurrence of tail-biting in undocked pigs. Thus, the

substrates dried corn silage and alfalfa hay were used to enable the piglets to perform their

natural exploration and foraging behaviour. Furthermore, the intensity and duration of

occupation with the material provided and the different behavioural patterns of the piglets

were analysed by video observation.

2. Materials and methods

2.1. General aspects

The pigs in the present study were kept on the research farm of the Chamber of Agriculture of

Schleswig-Holstein (Futterkamp), Germany, in accordance with EU Directive (2008/120/EG)

and EU Directive (2010/63/EG) and in accordance with the Tierschutz-

Nutztierhaltungsverordnung (TierSchNutztV, 2006). In case of tail-biting outbreaks,

manipulable material was provided in control pens as well to avoid the endangerment of

animal welfare. Identified biters were removed from the pen and injured piglets were

medically treated. If tail-biting did not abate, a separation of piglets was carried out.

2.2. Animals and housing

Data collection was carried out between September 2013 and April 2014. Farrowing and

rearing followed conventional farming practices; the farm size was 400 sows and 2,500

rearing places. In the present study, 721 crossbreed piglets (Pietrain x (Large White x

Landrace)) from 60 litters were housed in ten batches. Each batch corresponded to a

farrowing week. The piglets had an average birth weight of 1.4 ± 0.3 kg. The suckling period

took place in conventional farrowing systems (5.2 m² per pen), tails were not docked and

males were not castrated. From the second week of life until weaning, the piglets received a

45

pre-starter diet (14.6 MJ ME, 17.5 % protein, 1.45 % lysine, 0.25 % sodium). The piglets

were weaned after on average 28 days with an average weaning weight of 8.0 ± 1.7 kg.

Rearing lasted for 40 days until an average weight of 25.4 ± 2.3 kg. The piglets were housed

in mixed gender groups consisting of one or two litters (12 or 24 piglets per pen) with an

average space allowance of 0.38 to 0.42 m² per animal. According to the units, the feeding

system was either mash or dry feed ad libitum with an animal to feeding place ratio of 2:1.

For the first two weeks of rearing the piglets received a starter diet (14.4 MJ ME, 18.0 %

protein, 1.40 % lysine, 0.20 % sodium), thereafter the diet was gradually changed over the

next four days and fed until day 40 of rearing (13.4 MJ ME, 17.0 % protein, 1.30 % lysine,

0.25 % sodium). The drinking system consisted of nipples and bowls, the floor was fully

slatted and no bedding material was offered. Plastic sticks, plastic balls and hard wooden

sticks were provided as enrichment material. The environmental temperature during rearing

was automatically regulated by forced ventilation. It was set at 29.5°C on day one of rearing

and decreased stepwise until 22.0°C on day 40. The animals had full artificial lighting

between 06:00 h and 18:00 h.

2.3. Experimental design

In total, 721 piglets were divided randomly into three treatment groups litter-wise: a control

group (CG) with 231 long-tailed piglets housed without raw material, a dried corn silage

group (SG) and an alfalfa hay group (AG) with 245 long-tailed piglets each. In the farrowing

units, 20 litters were used for each treatment, two litters of each treatment group (n = 3) per

batch (n = 10) respectively. After weaning, the piglets were housed either litter-wise or two

litters were mixed, resulting in 14 pens for each treatment with two different group sizes in

the rearing units (12 or 24 piglets per pen). A schematic view of the experimental set-up

during rearing is given in Figure 1. Within each of the ten batches, the number of CG-, SG-,

and AG-pens was balanced and the locations of the treatment groups within the units were

randomised.

46

Figure 1: Schematic view of the experimental set-up regarding rearing.

2.4. Treatments

The provision of raw material took place from the second week of life until the end of rearing

twice a day (in the morning and in the afternoon) in the piglet nest (farrowing) or in a piglet

bowl (Fig. 2, Ø 40 cm) with an animal to occupation place ratio of 1.2:1 (12 piglets/pen) or

2.4:1 (24 piglets/pen) during rearing. The amount of dried corn silage offered per day and pen

was about 100 g, the amount of alfalfa hay about 120 g/day/pen, which corresponds to a

handful of material two times per day. In pens affected by tail-biting, the intervention scheme

was a jute sack (fixed on the pen wall), a handful of long, chopped straw on the pen floor,

grass silage or straw-peat mixture provided in piglet bowls two times per day. Treatment with

intervention material was also applied in CG-pens if an outbreak occurred. Identified biters (n

= 3) were removed from the pen and injured piglets were medically treated. If tail-biting did

not abate, a separation of piglets within the treatment groups was carried out (three pens in

total).

Total number

Treatment groups

Housing

Control (CG)

n = 231 (♀110, ♂121),

20 litters

Corn silage (SG)

n = 245 (♀121, ♂124),

20 litters

Alfalfa hay (AG)

n = 245 (♀128, ♂117),

20 litters

Six batches with three pens

à 24 piglets

Four batches with six pens

à 12 piglets

n = 721, 60 litters

47

Figure 2: Raw material treatment (AG) in piglet bowl.

2.5. Data collection

2.5.1. Scoring

Scoring of tail lesions and tail losses took place weekly during farrowing and rearing and was

carried out by only one person. The scoring scheme (modified from Abriel and Jais, 2013)

classified the severity of tail lesions with a four-point score consisting of “no visible damage”

(0), “scratches, light bite marks” (1), “moderate damage” (2) and “severe damage” (3). A tail-

biting outbreak was defined as a point in time when at least one piglet showed moderate

damage on the tail (Score 2). Tail losses were classified by “original length of tail” (0), “loss

of tail tip” (1), “partial loss” (2) and “total loss” (3). Furthermore, the gender and the size of

the animals (small, medium, large, in relation to pen mates) were recorded.

2.5.2. Weight gain

Weight was recorded at pen level in the beginning and in the end of rearing. Due to data

transmission problems group weights of only six batches (27 pens) were available (4-9,

missing 1-3 and 10). The pens were equally distributed over the treatment groups.

2.5.3. Video surveillance

To investigate the active behaviour of the animals and the duration of occupation with the raw

material, three farrowing units and three rearing units were equipped with colour cameras

(Santec, VTC-249IRP/W or VTC-279/IRPWD). In total, 99 piglets during farrowing (five pens

48

of AGs, three pens of SGs) and 188 piglets during rearing (four pens for each treatment

group) were video recorded 24 hours every day. The HeitelPlayer software (Xtralis

Headquarter D-A-CH, HeiTel Digital Video GmbH, Kiel, Germany) was used to watch the

videos. Five different behavioural patterns, which were observed mutually exclusively, were

coded. The ethogram is given in Table 1. The time budgets of each animal were investigated

by instantaneous scan sampling at 10 min intervals from 06:00 h to 18:00 h. Additionally, a

one-minute sampling interval was used for the first 10 minutes after raw material provision to

determine the number of piglets occupied by the material.

Table 1: Ethogram used for video observation in the 10 min sampling frame.

2.6. Statistical procedures

The software SAS 9.2® (SAS, 2008) or R (version 3.2.3) was used for statistical analysis.

The fit statistics AICC “Akaike’s information criterion corrected” (Hurvich and Tsai, 1989)

and the BIC “Bayesian information criterion” (Schwarz, 1978) were used to evaluate the

fitting of the models. Fixed effects were added stepwise to the models. The model with the

smallest AICC and BIC was chosen for the analysis. Significant differences in the least-

square-means were adjusted with the Bonferroni-correction (p < 0.05), (Westfall et al., 2011).

Behaviour Description


Sitting Body supported by hind-quarters and stretched front

legs

Standing Body supported by four stretched legs, includes

locomotion


Occupation with raw material Sniffing, nosing or rooting the raw material in

piglet bowl/nest

49

2.6.1. Tail lesions and tail losses

The data of tail lesions and tail losses followed a multinomial distribution. Multiple marginal

binomial models were used to test the different scoring classes (0-3) of tail lesions and tail

losses independently. The R function glht was used for post hoc comparison (Hothorn et al.,

2008). Due to the fact that tail-biting did not occur during farrowing, the data for the

statistical analysis was limited to the rearing period. The fixed effects treatment group (CG,

SG, AG), batch (1-10), week after weaning (1-6) and the interaction between treatment group

and batch were used in the final models for each class of tail lesions (0-3) separately. The first

week after weaning was excluded from the analysis due to unfavourable data distribution.

Only the last observation at the end of rearing was taken into consideration regarding tail

losses. The treatment group (CG, SG, AG) and the batch (1-10) were used as fixed effects in

the final models for each class of tail losses (0-3) separately. The effect of group size and

space allowance cannot be analysed separately from the effect of batch, because both effects

are confounded. Piglets in batch 1, 2, 5, 7, 8, 10 were housed in groups á 24 piglets, whereas

piglets in batch 3, 4, 6, 9, were housed in groups á 12 piglets.

2.6.2. Weight gain

In order to estimate the effect of tail-biting on total weight gain during rearing the MIXED

procedure was used. For every treatment group and scoring scheme of tail lesions and tail

losses nine pens were ranked regarding the total number of piglets with a score higher than

Score 0 within each pen, resulting in three pens for a low, respectively medium and high level

of tail lesions and tail losses (only last observation was taken into consideration). The level of

tail lesions/tail losses (low, medium, high), the treatment group (CG, SG, AG) and the

interaction between level of tail lesions/tail losses and treatment group were used as fixed

effects in both models.

2.6.3. Video analysis

The trait occupation with the raw material provided was investigated with one model for both

areas (farrowing and rearing). Occupation was coded as a binary trait (0: not occupied, 1:

occupied). The GLIMMIX procedure was used with the link function logit. The fixed effects

treatment group (SG, AG), batch (1-3), day after first raw material provision (1-43) and the

50

interaction between treatment group and day after first raw material provision were used in

the final model. The pen (nested within batch) was included as a random effect.

The trait active behaviour was analysed with one model for farrowing. The behavioural

patterns sitting, standing, feeding and occupation with raw material were summarised as

“active”. Lying behaviour was counted as “inactive” in further analysis. The active behaviour

was coded as a binary trait (0: inactive, 1: active). The GLIMMIX procedure was used with

the link function logit. The fixed effects treatment group (CG, SG, AG), batch (1-3), day after

weaning (1-28), daytime (6-18h), as well as the interaction between treatment group and day

after weaning were used in the final model. The pen was included as a random effect.

3. Results

All values in the following chapter are predicted values derived from the statistical models

used.

3.1. Tail lesions and tail losses

The effect of batch, week after weaning and the interaction between treatment group and

batch had highly significant influences on all classes of tail lesions (p < 0.001). The effect of

the treatment group had highly significant impact on Class 0 and Class 3 of tail lesions (p <

0.001). Tail lesions in Class 2 tended to be influenced by the treatment group (p = 0.05).

There was no significant effect of the treatment group on tail lesions in Class 1 (p = 0.4). Tail-

biting started on average two to three weeks after weaning with a tail lesion score higher than

0 in 26.5 % of the piglets in the third week (Fig. 3) and occurred in all pens. In the fifth week

after weaning tail lesions reached a peak (73.0 % of the piglets with scores higher than 0) and

decreased approximately 9.7 % until the last week of rearing. The first tail losses occurred

one to two weeks after the first tail lesions had become visible.

51

a* Refers to small, moderate and severe tail lesions. a-e Values were tested within class. Different superscripts differ significantly (p < 0.05).

Figure 3: Estimated frequencies of tail lesions over six weeks after weaning.

The effect of batch had highly significant influences on all classes of tail losses at the end of

rearing (p < 0.001). The effect of the treatment group had significant impact on Class 2 (p <

0.001) and Class 3 (p = 0.02). Tail losses in Class 0 tended to be influenced by the treatment

group (p = 0.08). There was no significant effect of the treatment group on tail losses in Class

1 (p = 0.28). Piglets lost their tails to the highest extent in CGs (48.7 %), followed by AGs

(45.2 %) and SGs (41.3 %), (Fig. 4).

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2 3 4 5 6

Est

imat

ed f

req

uen

cies

of

tail

lesi

on

s

Week after weaning

Severe lesions

Moderate lesions

Small lesions

No lesions

a b c d

c

e

a*

b

c

c

b

c

c

d

b

c c c

52

a-b Values were tested within class. Different superscripts differ significantly (p < 0.05).

If no letters are given, no significance was found.

Figure 4: Estimated frequencies of tail losses comparing the treatment groups at the end of

rearing.

The highest number of tail losses (Score > 0) occurred in batch one (98.6 %), whereas the

lowest number of tail losses was documented in batch ten (8.5 %). Tail losses in other batches

ranged from 66.7 % (batch six) to 9.9 % (batch nine), (Fig. 5).

1 2 3 4 5 6 7 8 9 10 Original length

a be be bd cd ad cd bd e e

Loss of tail tip

acd abcd acd abd ac b b d c ac

Partial loss a b b b a b b b - - Total loss a - a - a - - a - - a-e Values were tested within class. Different superscripts differ significantly (p < 0.05).

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Control Alfalfa hay Corn silage

Est

imat

ed f

req

uen

cies

of

tail

loss

es

Total loss

Partial loss

Loss of tail tip

Original length

a, b ab

53

Figure 5: Estimated frequencies of tail losses over ten batches at the end of rearing.

3.2. Weight gain

The level of tail lesions and tail losses and the treatment group had no significant influences

on the total weight gain during rearing (p > 0.05). The interaction of the number of tail lesions

and treatment group, as well as the interaction of number of tail losses and treatment group

had significant effects on the total weight gain during rearing (p < 0.05). Piglets in CGs

gained less weight in pens with high levels of tail lesions/tail losses (LS-Mean ± se: 16.9 ± 1.0

kg/15.6 ± 1.0 kg) in comparison to pens with a low level (19.9 ± 1.0 kg /18.9 ± 1.0 kg). The

total weight gain of piglets in SGs was comparable. Piglets in AGs gained less weight in

medium levels of tail lesions/tail losses (both 14.8 ± 1.0 kg) in comparison to pens with low

and high levels (18.5 ± 1.0 kg vs. 16.5 ± 1.0 kg). Differences in total weight gain between the

treatment groups within the levels of tail lesions and tail losses were not significant (p > 0.05).

3.3. Video analysis

The effect of day after first raw material provision and the interaction of the treatment group

and the day after first raw material provision had highly significant influences on the number

of piglets occupied with the raw material provided (p < 0.001). The effect of the treatment

group showed tendencies (p = 0.10). The number of piglets occupied by alfalfa hay differed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2 3 4 5 6 7 8 9 10

Est

imat

ed f

req

uen

cies

of

tail

loss

es

Batch

Total loss

Partial loss

Loss of tail tip

Original length

54

significantly between the end of farrowing (day 6-15 after first raw material provision, p <

0.05) and the end of rearing (day 38-43 after first raw material provision, p < 0.05). The

number of piglets occupied by corn silage did not differ between farrowing and rearing (p >

0.05), (Fig. 6).

Figure 6: Least-square-means of the percentage of animals occupied with raw material

during ten minutes after provision regarding the interaction between treatment

group and day after first raw material provision in three batches. Day one after

first raw material provision corresponds to day 12 of life.

The batch, the day after weaning, the daytime, as well as the interaction between the treatment

group and day after weaning had highly significant influences (p < 0.001) on the overall

active behaviour during rearing. The treatment group had no significant influences on the

overall activity (p > 0.05). The data showed a two-phase activity curve with a peak between

10:00-11:00 h and 14:00-15:00 h. The activity of the piglets was highest on the first day after

weaning, as well as between two and three weeks after weaning and decreased towards the

end of rearing (Fig. 7).

55

Figure 7: Least-square-means of the percentage of active animals during rearing regarding

the interaction between treatment group and day after weaning in three batches.

Weaning age was on average 28 days of life.

4. Discussion


No tail-biting was observed in any of the treatment groups during farrowing. This finding is in

line with Munsterhjelm et al. (2009), who did not observe tail lesions either in enriched or in

barren pens in the first four weeks of life. Tail-biting occurred on average in the second until

third week after weaning for the first time, followed by tail losses one to two weeks later. This

finding supports the work of Abriel and Jais (2013), who found increasing tail-biting

behaviour in the second week after weaning. An explanation for the beginning of tail-biting in

the early rearing phase could be the number of conversions the piglets are faced with during

the weaning process. When separated from the sow, they need to adapt to a new environment

and feeding, at the same time their immune system is forced to deal with a new germ

environment. Under natural conditions weaning is a gradual process in piglets and is not

complete until 10–12 weeks of age (Lallès et al., 2007). Furthermore, the mixing of piglets

56

and, therefore, rank order fights contribute to a stressful situation for weaned piglets (Hötzel

et al., 2011). In intensive housing systems, however, the animals often fail to gain control

over aversive situations using evolved coping strategies, and it is argued that abnormal

behaviour can originate from unsuccessful coping (Wechsler, 1995).

The interaction between the treatment group and batch had a highly significant influence on

tail lesions. The numbers of tail lesions were variable regarding the treatment groups and the

batches and did not follow a clear trend. The variation in the amount of tail lesions supports

the assumption that environmental conditions (e.g. climate, pen structure, group size, feeding

spaces, ventilation and health statues) play an important role in the occurrence of behavioural

disorders (Taylor et al., 2012). The group sizes and the feeding and drinking systems differed

between batches in the present study. No clear connection between group sizes and unit

facilities could be drawn for the levels of tail lesions between the batches.

Furthermore, the effect of batch had highly significant influences on tail losses at the end of

rearing. The decreasing number of tail losses at the end of the study could be explained by

enhanced and more precise animal observation by stable staff and points out the learning

process in the course of the batches. The staff members reacted faster in case of tail-biting

outbreaks, using tail lesions as an indicator, and offered for example jute sacks or a straw-

peat-mixture to the pigs as additional occupation material. Thus, tail lesions were able to heal

again and did not result in tail losses. In addition, the European Food Safety Authority has

pointed out as useful good stockmanship and intervention before severe outbreaks become

established (EFSA, 2007).

Raw material tended to reduce the amount of tail losses at the end of rearing, the effect was

more pronounced in severe classes of tail losses. Curative measurements were also carried out

in CGs to avoid severe injuries and welfare problems in the case of tail-biting outbreaks,

which could have led to an approximation to the raw material groups. Tail-biting in CGs

might have provoked higher numbers of tail losses if intervention had not been carried out.

The provision of raw material in the present study was only a limited change in housing

conditions in order to reduce the risk for tail-biting. Other risk factors might also contribute to

a stressful situation for the piglets, such as fully slatted floors and restricted access to raw

material in larger group sizes, which was shown by Chambers et al. (1995) and Van de Weerd

et al. (2006). These risk factors all contributed to the overall risk of tail-biting and need to be

57

taken into account for evaluation of the results. The improvement in intensive housing

conditions by daily raw material provision in the present study was not sufficient enough to

prevent tail-biting but could reduce the occurrence of the behavioural disorder in long-tailed

pigs. This supports the findings of Zonderland et al. (2008), who concluded that tail-biting is

best prevented with a small amount of straw (20 g/animal/day), provided twice daily.

4.2. Weight gain

The lower total weight gain of piglets in high classes of tail lesions/tail losses in comparison

to low classes, which was found for CGs and SGs, were in line with Camerlink et al. (2012),

who found that pigs which were subjected to more tail-biting, ear-biting and paw-biting, grew

less well (p < 0.05). Moreover, Wallenbeck and Keeling (2013) stated that tail-biting victims

received decreased daily feed intakes during and after the tail-biting outbreaks. Nevertheless,

daily weight gain of piglets in AGs seemed not to be affected by high levels of tail lesions/tail

losses and differences between the treatment groups within the levels of tail lesions and tail

losses were not significant. Moreover, the limited weight data (27 pens) made it difficult to

draw general conclusions.

4.3. Video analysis

Corn silage attracted the piglets’ attention during the whole observation period, whereas the

attractiveness of the alfalfa hay decreased towards the end of rearing. A possible explanation

could be a better palatability of the material due to a higher concentration of carbohydrates

and lower dry-matter content in comparison to alfalfa hay, which contains more fibres. The

preference of pigs for roughage with a low dry-matter content and the attractiveness of

glucose/sucrose for pigs was shown by Olsen et al. (2000) and Kennedy and Baldwin (1972).

The higher acceptance of corn silage and therefore sustainable occupation could have led to

lower tail losses in SGs in comparison to AGs and CGs at the end of rearing (see Fig. 4). In

the present study, a fresh replacement twice a day should have ensured the raw material

remained of interest to the animals because of the novelty aspects (Wood-Gush and

Vestergaard, 1991; Van de Weerd et al., 2003). However, provision in the piglet bowl did not

allow every piglet to reach the raw material at the same time, which could have contributed to

the development of the behavioural disorder. According to Van de Weerd et al. (2006), the

58

limited size of a point source may restrict access to enrichment causing competition,

aggression or restlessness in groups of animals. Especially in larger group sizes (> 12 piglets),

more than one piglet bowl should be used for the provision of raw material.

Pig activity has been identified as a promising tool to predict tail-biting outbreaks in previous

studies (Statham et al., 2009). The two-phase activity curve during the day contributes to the

findings of Docking et al. (2008) and Zwicker et al. (2012), who found a synchronisation of

feeding and foraging behaviour within a group of pigs. It was notable that the active

behaviour in all treatment groups increased in the second and third week after weaning, which

could be an indication of the beginning of tail-biting behaviour as described above (see Fig.

3). Nevertheless, the small sample size of piglets analysed during rearing (n = 188) makes it

difficult to transfer results from video observation to the tail-biting behaviour of the total

number of piglets in the present study (n = 723). Furthermore, there was no clear association

between active behaviour and the level of tail-biting within the batches. Thus, the finding of

Zonderland et al. (2010b), who connected higher active behaviour with higher tail lesions and

tail losses, is not supported by the present study.

5. Conclusion

Additional raw material provision in the piglet nest during farrowing had no effects on the

occurrence of tail-biting during rearing. Tail-biting started on average in the second and third

week after weaning, thus, precise surveillance in this sensitive phase of rearing is highly

recommended. Tail losses were best prevented by dried corn silage. Nevertheless, the effect

of batch on tail-biting during rearing was more pronounced than the effect of raw material

provision. The amount of tail losses at the end of rearing was reduced through improvements

in animal observation.

Conflict of interest

The authors declare that there is no conflict of interest.

Acknowledgements

This work was financially supported by the working group animal welfare of “Rügenwalder

Mühle”.

59

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63

CHAPTER TWO

The effect of mixing after weaning on tail-biting during rearing with

characterisation of performers and receivers of manipulative behavioural

patterns

C. Veit1, K. Büttner1, J. Salau1, O. Burfeind2, E. grosse Beilage3, J. Krieter1

1Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Kiel, Germany

2Chamber of Agriculture, Schleswig-Holstein, LVZ Futterkamp, Blekendorf, Germany

3Field Station for Epidemiology, University of Veterinary Medicine, Hannover, Germany

64

Abstract

The aim of this study was to reveal the effects on tail-biting during rearing of housing

acquainted piglets in comparison to piglets out of mixed litters. The treatment groups “litter-

wise” (LG, n = 240) and “mixed litters” (MG, n = 238) were housed in five identical units

with an additional daily offer of alfalfa hay. Each tail was scored regarding tail lesions/ tail

losses once per week with a four-point score (0 = no damage/ original length to 3 = severe

damage/ total loss). Individual body weights of the piglets at weaning (on average 28 days of

age), at day 16 and at day 40 of rearing were collected. The effect of week after weaning, the

batch and the interaction of treatment group and batch had highly significant influences on tail

lesions (p < 0.001). Tail-biting started in the second week after weaning, with an increasing

development during rearing. First tail losses were observed in the fourth week after weaning.

The batch and the interaction of group and batch had highly significant influences on tail

losses at the end of rearing (p < 0.001). There was no clear trend between the treatment

groups and the batches regarding tail lesions and tail losses. Furthermore, tail-biting did not

affect daily weight gain. To investigate the behaviour of the animals in regard to a tail-biting

outbreak, the piglets of four units were marked individually and observed by video 24 hours

per day. Recorded video material of five pens (60 piglets) was under analysis by

instantaneous scan sampling and continuous observation. Based on the frequencies of the

manipulative behaviour performed, the individual character (CS) of each piglet was defined as

receiver, performer or neutral. The day, the daytime and the pen had highly significant effects

on the frequencies of tail exploration, belly nosing and nosing behaviour (p < 0.001). The

frequencies of tail exploration increased over five days prior to a scored tail-biting outbreak.

The frequencies of belly nosing decreased with increasing distance to weaning. Receivers of

nosing lay significantly more frequently than performers, whereas performers of nosing and

belly nosing stood significantly more frequently than receivers of the respective behaviour

(p < 0.05). The hypothesis of a prevention of tail-biting during rearing through a renunciation

of mixing after weaning could not be confirmed in the present study. It needs to be taken into

account that every piglet has different coping strategies to react to environmental changes and

today’s intensive husbandry may overtax this adaptive ability.

65

1. Introduction

Tail-biting in pigs is a welfare problem with multifactorial causes. Higher stocking densities

and deficiencies in feed quality or accessibility (Moinard et al., 2003), poor ventilation

(Hunter et al., 2001), as well as a lack of rooting substrate (Zonderland et al., 2008) have been

identified as environmental risk factors. On the biological side, poor health (Day et al., 2002),

breed (Breuer et al., 2003) and gender (Zonderland et al., 2010a) could also play a role.

Former studies have pointed out a concentration of abnormal behaviour during the early

rearing phase in long-tailed piglets (Abriel and Jais, 2013). This assessment should direct the

focus on the challenges piglets are faced with through the weaning process. Besides the

change in environment and diet, as well as the separation from the sow, the mixing of

unfamiliar litters is one of the possible stressors during weaning in commercial farming

systems (D'Eath, 2005). Due to management practices piglets are often sorted by gender and

size and rehoused in rearing pens. Confrontation with unfamiliar pen mates leads to rank

order fights in the first days after weaning and regrouping. According to Hötzel et al. (2011),

the mixing of litters implicates higher frequencies of agonistic and exploratory behaviours,

lower resting frequencies and a higher proportion of severe skin lesions in comparison to

unmixed litters. In addition, Fraser et al. (1974) pointed out that familiarity, in the sense of

prior exposure to a stranger, reduces aggression. Piglets which are socialised prior to weaning

formed a new stable dominance hierarchy more quickly when mixed again after weaning

(D'Eath, 2005). Furthermore, familiarising piglets from different litters reduces social stress at

weaning and increased weight gain afterwards (Kutzer et al., 2009). Environmental factors

which disturb the normal hierarchy can result in frustration and aggression (Schrøder-Petersen

and Simonsen, 2001). This may, in turn, increase the risk of tail-biting. Pigs in group-

farrowing systems are more tolerant of unfamiliar pigs when mixed, compared to pigs reared

in confinement systems (Li and Wang, 2011). Bohnenkamp et al. (2012) stated that the early

mixing of unacquainted litters during lactation reduces agonistic behaviour and lesion score

difference during the first two days after weaning. Although the effects on tail-biting of social

status and events such as mixing have received limited attention, mixing may act in triggering

tail-biting under commercial conditions (EFSA, 2007). Based on these results, the hypothesis

was proposed that the avoidance of stress through mixing after weaning has positive effects

66

on the manifestation of behavioural disorders. Therefore, litter-wise and mixed-housed piglets

were compared regarding tail lesions and tail losses during rearing.

Moreover, detailed information on piglet behaviour at an individual level is still insufficient.

Hessing et al. (1993) found the existence of behavioural strategies in piglets to cope with

conflict situations. Koolhaas et al. (1999) concluded that there are distinct phenotypes

(proactive and reactive coping styles) which are more or less stable over time in their

response to stressors and, thus, may adapt differentially to environmental conditions. Thus, a

further aim of the present study was the investigation of the performers and receivers of

manipulative behavioural patterns (tail exploration, belly nosing and nosing). The focus was

on video observations of five days prior and the day of a tail-biting outbreak itself.

2. Materials and methods

2.1. Animals and housing

Data collection was carried out on the research farm of the Chamber of Agriculture of

Schleswig-Holstein (Futterkamp), Germany, between February and April 2014. In the study,

478 crossbreed piglets (Pietrain x (Large White x Landrace)) from 40 litters were used in five

batches and kept under conventional farming practices. Tails were not docked and males were

not castrated. The piglets were weaned on average at 28 days with an average weaning weight

of 8.3 ± 1.6 kg. Five identical rearing units consisting of eight pens each were consecutively

used. Rearing lasted for 40 days in mixed-gender groups until an average weight of

25.9 ± 3.8 kg. The groups consisted of 12 piglets per pen with a space allowance of 0.38 m²/

animal. The used feeding system was mash feed ad libitum with an animal to feeding place

ratio of 2:1 and a diet composition of 17.0 % protein, 1.3 % lysine, 0.7 % calcium and 0.25 %

sodium (13.4 MJ ME). Water was accessible through nipple drinkers. The plastic floor was

fully slatted and no bedding material was provided. One plastic ball per pen (suspended on a

metal chain) and alfalfa hay in plastic bowls (one per pen, Ø 40 cm, animal to occupation

place ratio 1.2:1) was provided as environmental enrichment material once per day. The

environmental temperature was automatically regulated by forced ventilation. It was set at

28.0 °C on day one of rearing and decreased stepwise until 24.0 °C on day 40. The animals

had full artificial lighting between 06:00 h and 19:00 h. Pigs in the present study were kept in

67

consideration of the European Directive (2008/ 120/ EG) and in accordance with the

Tierschutz-Nutztierhaltungsverordnung (TierSchNutztV, 2006).

2.2. Experimental design

In total 478 piglets were divided randomly into two groups, 240 piglets (♂ 124, ♀ 116) were

housed in litter-consisting groups (LG), whereas 238 piglets (♂ 117, ♀ 121) were mixed out

of at least three different litters (MG). Each unit consisted of four pens with LGs and four

pens with MGs, resulting in 20 pens for each treatment. The locations of the treatment groups

within the units were randomised.

2.3. Data collection

2.3.1 Scoring

Scoring of tail lesions and tail losses was carried out weekly. The scoring scheme (modified

from Abriel, Jais, 2013) classified the severity of tail lesions with a four-point score consisting

of “no visible damage“ (0), “scratches, light bite marks” (1), “moderate damage” (2) and

“severe damage” (3). A tail-biting outbreak was defined as a point in time, when at least one

piglet showed a freshly bleeding tail wound or a loss of the tail. Tail losses were classified by

“original length of tail” (0), “loss of tail tip” (1), “partial loss” (2) and “total loss or necrosis”

(3). Furthermore, the gender and the size of the animals (small, medium, large, in relation to

pen mates) were recorded during the scoring process.

2.3.2 Body weight

Individual body weights of the piglets at weaning, at day 16 and at day 40 of rearing were

collected.

2.3.3 Video surveillance

In total 32 pens (four units) were equipped with colour cameras and recorded 24 hours per

day (Santec, VTC-249/ IRP/ W or VTC-279/ IRPWD). The piglets were individually marked

with colour spray three times per week. The open source software BORIS (Friard, 2014) was

used for the video analysis of five pens (three MGs, two LGs). In total 60 piglets (♂ 29, ♀ 31)

68

were analysed five days prior to a scored tail-biting outbreak and the day of an outbreak itself.

Eleven different behavioural patterns were coded. The ethogram is given in Table 1.

Table 1: Ethogram used for video observation.

Behavioural pattern Description

Instantaneous scan sampling


Standing Body supported by four stretched legs, includes

locomotion


Occupation with raw material Sniffing, nosing or rooting the raw material in piglet bowl

Pen investigation Head on the pen surrounding (floor and walls)

Continuously collected

Tail exploration

• Performer Head on the tail of a pen mate, includes tail-in-mouth and tail-biting behaviour

• Receiver Being manipulated by a pen mate on the tail, includes tail-in-mouth and tail-biting behaviour

Belly nosing

• Performer Manipulation of the abdomen of a lying pen mate

• Receiver Being manipulated by a pen mate on the abdomen, while lying

Nosing

• Performer Snout contact with any part of the body of a pen mate except the belly region

• Receiver Being contacted by snout on any part of the body, except the belly region

69

Time budgets of each animal were investigated by instantaneous scan sampling over 20

minutes from every second hour between 06:00 h and 18:00 h (06:00 h to 06:20 h, 08:00 h to

08:20 h, 10:00 h to 10:20 h, 12:00 h to 12:20 h, 14:00 h to 14:20 h, 16:00 h to 16:20 h and

18:00 h to 18:20 h), the sampling scheme was every 2 minutes. Every 20 min interval is

counted as a scan, resulting in 42 scans per pen over six days, respectively 210 scans in total.

Due to technical difficulties, there was a lack of 17 scans, thus, the data was limited to 193

scans. Additionally, the manipulative behavioural patterns tail exploration (te), belly nosing

(bn) and nosing (no) were recorded continuously over the above-mentioned time frame

determining the receivers (R) and performers (P) of each behaviour. In order to make the

piglets’ behaviour comparable and classifiable, the frequencies of the recorded manipulative

behavioural patterns required a conversion into scores/ indices. The character score (CS) was

developed to assign a number to each piglet (i), defining it as receiver or performer by

changing the algebraic sign. The following formula defines CS, where x ∈{te, bn, no}, y ∈

{1, 2, 3, 4, 5} and i ∈ {1,…,60}:

CSx,y (i) = [Px(i)/ max_Px,y] - [Rx(i)/ max_Rx,y] (1)

Px(i) is the number of manipulative contacts as performer of behaviour x for piglet i and

max_Px,y is the maximum number of manipulative contacts as performer in pen y. Rx(i) is the

number of manipulative contacts as receiver of behaviour x for piglet i and max_Rx,y is the

maximum number of manipulative contacts as receiver in pen y. CS ranges between -1

(absolute receiver) and +1 (absolute performer);

In order to determine the ranges (upper limit (UL) and lower limit (LL)) of CS to assign

piglets to different character categories, the following formulas were used:

ULx,y = MWx,y + 0.52 x std x,y (2)

LLx,y = MWx,y – 0.52 x std x,y (3)

MWx,y denote the mean and std x,y denote the standard deviation of CS x,y. The constant 0.52 is

the 70 %-quantile of the standard normal distribution. Piglets with CSs within the range of UL

and LL were designated “neutral”. Piglets with a CS which exceeded the UL were named

“performer” and piglets with a CS below the LL were named “receiver”.

70

2.4. Statistical analysis

The software package SAS 9.2® was used for statistical analysis (SAS, 2008). The fit

statistics AICC “Akaike’s information criterion corrected” (Hurvich and Tsai, 1989) and the

BIC “Bayesian information criterion” (Schwarz, 1978) were used to evaluate the fitting of the

models. The fixed effects were added stepwise to the models. The model with the smallest

AICC and BIC was chosen for the analysis.

2.4.1. Tail lesions and tail losses

The data of tail lesions and tail losses followed a multinomial distribution (Scores 0-3). Thus,

the GLIMMIX procedure was used assuming a cumulative logit link function for the

multinomial distributed data. The fixed effects treatment group (LG, MG), week after

weaning (1-6), batch (1-5) and the interaction of treatment group and batch were added

stepwise and used as fixed effects in the final model for tail lesions. The piglet was included

as a random effect and was nested within group and batch. The database was limited to the

last observation at the end of rearing regarding tail losses. The fixed effects group (LG, MG)

and batch (1-5) and the interaction of group and batch were used as fixed effects in the final

model for tail losses.

2.4.2. Weight data

In order to estimate the effect of tail-biting on daily weight gain, the MIXED procedure was

used. Daily weight gain of three time periods was analysed: weaning to day 16 (period 1), day

16 to day 40 (period 2) and weaning to day 40 (period 3). The scores of tail lesions on day 16

and day 40, as well as the scores of tail losses on day 40 of rearing were classified by

distribution: class 0 (0), class 1 (1) and class 2 (2, 3) for tail lesions, as well as class 0 (0) and

class 1 (1, 2, 3) for tail losses. Low frequencies of tail losses in the study did not allow the

distinction into three classes, which may confound the gradations. Classes of tail lesions (0, 1,

2) on day 16 were added as fixed effects to the model for period 1, whereas classes of tail

lesions and tail losses on day 40 were added as fixed effects to the model for period 2 and

period 3. Period 1 was not analysed for tail losses, because they were not observed until four

weeks after weaning. The treatment group (MG, LG), the batch (1-5), the interaction of group

and batch and the gender were used as fixed effects in all models. Weaning weight was added

71

as a covariable to the final models. Significant differences in the least-square-means were


2.4.3. Video analysis

Video data was limited to five pens, since continuous observation of manipulative

behavioural patterns required a high time effort due to the assignment of performer and

receiver of each interaction. Therefore, the treatment groups (LGs, MGs) were not considered

in further statistical analysis.

The count data of the continuously observed manipulative behavioural patterns was analysed

using the GLIMMIX procedure with a Poisson-distribution. The fixed effects day (- 5, - 4, - 3,

- 2, - 1, 0), daytime (6, 8, 10, 12, 14, 16, 18) and pen (1-5) were used in the models for tail

exploration, belly nosing and nosing. The piglet (nested within pen) was added as a random

effect to the final models.

The accumulated frequencies of the behaviours lying, standing and feeding, which were

observed by instantaneous scan sampling of each piglet over six days (every 20 min of every

second hour from 06:00 h to 18:00 h), were analysed using the MIXED procedure. The

behaviours pen investigation and occupation with provided material were rarely shown by the

piglets, thus, not considered in further statistical analysis. Three different models were used to

test the effect of character (calculated by formulas 1 to 3) separately for tail exploration, belly

nosing and nosing. The character of the piglets (performer, neutral, receiver) for the respective

manipulative behavioural pattern and the pen (1-5) were used as fixed effects in the models

for lying, standing and feeding behaviour. Daily weight gain was added as a covariable to the

final models. The gender was removed from the models due to low improvements in the

fitting and no significant impact. Significant differences in the least-square-means were


3. Results


The effect of week after weaning, the batch and the interaction of group and batch had highly

significant influences on tail lesions (p < 0.001). The group had no significant effect

(p > 0.05). Tail-biting started on average in the second week after weaning with a tail lesion

72

score higher than 0 in 15.8 % of the piglets and increased towards the end of rearing (90.8 %

of the piglets with a score higher than 0) (Fig. 1). The first tail losses were observed on

average in the fourth week after weaning.

Figure 1: Estimated frequencies of tail lesions over six weeks after weaning.

The piglets in batch five had the highest number of tail lesions in both treatment groups (Fig.

2a and 2b).

73

Figure 2: Estimated frequencies of tail lesions over all batches in LGs (a) and MGs (b) .

The batch and the interaction of group and batch had highly significant influences on tail

losses at the end of rearing (p < 0.001). The group had no significant effect (p > 0.05). The

highest number of tail losses (Score > 0) occurred in LGs in batch three (65.4 %, Fig. 3a),

whereas in MGs the highest number of tail losses was documented in batch four

74

(81.4 %, Fig. 3b). Tail losses in other batches ranged from 18.8 % to 37.3 % in LGs, as well

as from 10.2 % to 27.6 % in MGs.

Figure 3: Estimated frequencies of tail losses over all batches, regarding the last week of

rearing, in LGs (a) and MGs (b).

75

3.2. Weight gain

The treatment group, the batch and the interaction of treatment group and batch had

significant influences on daily weight gain in all analysed periods (p < 0.01). Moreover, the

classes of tail lesions at day 40 had significant influences on daily weight gain in the

respective analysed periods (p < 0.05). The classes of tail lesions at day 16, the classes of tail

losses at day 40 and the gender had no significant effect on daily weight gain in the respective

analysed periods (p > 0.05). The least-square-means of daily weight gain regarding the effect

of different classes of tail lesions and tail losses in different time periods are given in Table 2.

The daily weight gain showed no clear trend over treatment groups and batches and could not

be connected with the weekly scoring of tail lesions (Fig. 2) and tail losses (Fig. 3).

Table 2: Least-square-means (LSM) and standard error (SE) of daily weight gain (g) in

three different time periods regarding the effect of different classes of tail lesions

and tail losses.

Period 1 (d1 - d16)

LSM ± SE

Period 2 (d16 - d40)

LSM ± SE

Period 3 (d1 - d40)

LSM ± SE

Tail lesions

Class 0 184.6 ± 4.15 534.0a ± 21.5 391.3a ± 15.3

Class 1 207.9 ± 10.7 594.4ᵇ ± 11.2 425.3a ± 7.97

Class 2 195.4 ± 9.54 617.5ᵇ ± 6.66 450.8b ± 4.74

Tail losses

Class 0 607.5 ± 6.36 441.7 ± 4.55

Class 1 598.9 ± 13.8 434.7 ± 9.88

a-b Values with different superscripts differ significantly (p < 0.05).

3.3. Video analysis

An overview of the frequencies of manipulative behaviour performed/ received per pig and

the average CS over all pens is given in Table 3.

76

Table 3: Mean, standard deviation (std), minimum (min) and maximum (max) of the

frequencies of manipulative behaviour performed/ received per pig and of the

character score (CS) of the respective behaviour.

Behaviour

n_performed/ received per pig CS

Mean ± std Min Max Mean ± std Min Max

Tail exploration 17.9 ± 9.70 1.0 43.0 -0.06 ± 0.35 -0.95 0.74

Belly nosing 20.3 ± 26.6 1.0 157 -0.10 ± 0.39 -0.93 0.95

Nosing 45.5 ± 29.2 1.0 146 -0.09 ± 0.36 -0.80 0.63

The day, the daytime and the pen had highly significant effects on the frequencies of tail

exploration, belly nosing and nosing performed (p < 0.001). The frequencies of tail

exploration performed increased towards the day of a scored tail-biting outbreak (LS-Means

of the day -5 differed significantly from the days -3, -2, -1, 0, p < 0.05, Fig. 4); whereas the

frequencies of belly nosing decreased (LS-Means of the days -5 to -1 differed significantly

from day 0, p < 0.05, Fig. 4). The frequencies of nosing reached its maximum on day -3 and

day -1 (Fig. 4).

77

Figure 4: Least-square-means of the frequencies of manipulative behaviour performed

on five days prior to a scored tail-biting outbreak and the day of an outbreak

itself.

In the daily course, the frequencies of manipulative behavioural patterns performed followed

the diurnal activity curve of the piglets and reached a maximum at 10:00 h and 16:00 h

(Fig. 5). The frequencies of belly nosing were highest in the pen which was observed most

closely (two weeks) to weaning (LS-Mean ± se: 0.73 ± 0.19 per piglet and scan) and

decreased with increasing distance to weaning (pens observed four weeks after weaning:

0.2 ± 0.05 to 0.41 ± 0.1; five weeks after weaning: 0.08 ± 0.02 to 0.19 ± 0.05, respectively).

78

Figure 5: Least-square-means of the frequencies of manipulative behaviour performed

during the day (06:00h to 18:00h).

The classified character of the piglets for nosing behaviour and the pen had significant

influences on the accumulated frequencies of lying (p < 0.05). The character of the piglets for

tail exploration and belly nosing behaviour had no significant effect on the frequencies of

lying (p > 0.05). The receivers of nosing lay significantly more frequently than the performers

(LS-Mean ± se: 276.3 ± 4.9 vs. 249.4 ± 5.1, p < 0.001). The character of the piglets for tail

exploration, belly nosing and nosing, as well as the pen had significant effects on the

frequencies of standing (p < 0.05). Performers of nosing and belly nosing stood significantly

more frequently than receivers of the respective behaviour (86.9 ± 3.6 vs. 61.5 ± 3.4,

respectively 89.0 ± 4.2 vs. 64.9 ± 3.8, p < 0.01). Performers of tail exploration tended to stand

more frequently than the receivers (84.3 ± 4.3 vs. 70.4 ± 4.0, p = 0.07).

4. Discussion


Tail-biting occurred on average in the second week after weaning for the first time, followed

by tail losses two weeks later. This is in line with Abriel and Jais (2013), who found

79

increasing tail-biting behaviour in the second week after weaning. Early weaning, which

under natural conditions is a gradual process that lasts until 10–12 weeks of age (Lallès et al.,

2007), is a challenging situation for the piglets and could trigger the stress-induced

behavioural disorder (Sinisalo et al., 2012). Animals are likely to develop abnormal behaviour

under housing conditions in which they fail to cope with aversive situations by performing

normal behaviour (Wechsler, 1995).

There was no clear trend between the treatment groups and the batches regarding tail lesions

and tail losses, except for high numbers of tail lesions in batch five in LGs and MGs. A

difference in treatment between the batches was the individual marking of the piglets in

batches one to four due to video observation. The piglets were treated three times per week

and therefore occupied for the time of colour application, which lasted about one to two hours

per unit. Moreover, the colour on the back of pen mates attracted the attention of the piglets

for a certain amount of time after treatment. Certainly, the individual marking was a stressful

measurement for the piglets but transient, not regularly repeated, short stress may not really

affect welfare but rather may be a suitable way to overcome boredom (Manteuffel, 2002). If

colour application is counted as environmental enrichment, it could be an explanation as to

why the number of tail lesions was lower in batches one to four in comparison to batch five.

The results of tail lesion scoring could imply that the highest number of tail losses occurred

subsequently in batch five. In contrast, the highest number of tail losses at the end of rearing

was noted for LGs in batch three and for MGs in batch four. These findings could be

explained by the different forms of tail-biting described by Taylor et al. (2010). In the case of

“two stage tail-biting”, a pre damage stage, which is characterized by tail-in-mouth behaviour,

turns after a while into a damage stage when first tail wounds are visible. This form of tail-

biting was easy to document by weekly scoring, because the process lasted for days. In the

case of “sudden forceful tail-biting”, the piglets’ tails were amputated partly by other piglets

within a short period of time, thus, not subsequently evaluated in high levels of tail lesions,

since wounds could heal more quickly.

Another attempt to explain the differences in tail lesions and tail losses between the batches

could be facility problems within the units. Even if the units were identical in construction,

provided the same feeding system, as well as the same pen sizes and structure, dysfunctions in

water or feed accessibility or climate variations, respectively, could have provoked

80

behavioural disorder. Taylor et al. (2012) determined the categories climate and environment

(temperature, humidity, draughts, aversive atmospheric factors) to be the highest risk factors

for tail-biting by using a husbandry advisory tool. Moreover, Hunter et al. (2001) showed that

insufficient accessibility to feed increased the risk of tail-biting.

4.2. Weight gain

The daily weight gain of piglets in high classes of tail lesions was significantly higher than in

low classes of tail lesions. Thus, the assumption that piglets which suffered from tail-biting

would gain less weight subsequently could not be supported by the results of the present

study. This is not in line with Camerlink et al. (2012), who found that pigs that received more

tail-biting, ear-biting and paw-biting grew significantly less well. An explanation as to why

tail-biting did not affect the daily weight gain in the present study could be the low average

number of severe tail lesions in the course of rearing, resulting in a low average level of tail

losses at the end of rearing. Moreover, heavier piglets seemed to be bitten more than lighter

piglets; they were probably less active (lay more frequently) and, thus, an easier aim for tail-

biters. This contributes to the work of Zonderland et al. (2010b), who found victims were the

heavier pigs in the pen.

4.3. Video analysis

The increasing frequencies of tail exploration prior to a tail-biting outbreak confirmed the

findings of Zonderland et al. (2010, 2011). Here, restlessness increased and the frequency of

performed tail bites tended to increase in the six days preceding a tail-biting outbreak. It needs

to be taken into account that the determined behaviour tail exploration included tail-in-mouth

behaviour (Tab. 1), which is described as a part of the “pre damage stage” in the development

of tail-biting (Taylor et al., 2010). In the weekly scoring of tail lesions, a tail-biting outbreak

was not scored until the so-called “damage stage” of behavioural disorder had occurred.

The frequencies of belly nosing were highest in the pen which was observed most closely to

weaning, which indicates a connection to the weaning process. According to Mason (1991),

belly nosing could be classified as a stereotype since it is repetitive and appears to have no

obvious function. Additionally, Gardner et al. (2001) stated that belly nosing does not appear

81

to be a general behavioural indicator of stress. It seems to be more a redirected suckling

behaviour due to early weaning (Widowski et al., 2008).

During video analysis, every piglet was assigned as receiver or performer of manipulative

behaviour in an observed interaction. Since every piglet was able to receive and perform the

respective behaviour simultaneously in the observed period, a clear distinction was not

possible. With formulas 1 to 3 the character of every piglet regarding the respective

manipulative behaviour was classified as performer, receiver or neutral in order to make them

comparable. The receivers of nosing behaviour lay significantly more frequently than the

performers, whereas the performers of nosing and belly nosing stood significantly more

frequently. Thus, receivers reacted less defensively and tolerated manipulation with the snout

more frequently, whereas performers showed higher general activity. Considering the

background of the controversially discussed behaviours, it needs to be taken into account that

nosing is a form of social contact and should not necessarily be counted as negative

behaviour. Nevertheless, Beattie et al. (2005) stated that tail-biting is linked to ear-biting and

nosing in the genital or belly region, respectively. Furthermore, it needs to be taken into

account that the CS were calculated from video data of only six days of rearing in the present

study and there were already indications that the individual character is not stable over time

(Stukenborg et al., 2012).

5. Conclusion

Stress due to regrouping after weaning may contribute to the occurrence of tail-biting as an

additional effect to other risk factors. However, in the present study, a renunciation of mixing

after weaning did not prevent tail-biting behaviour during rearing. There were differences in

individual pig characters and it needs to be taken into account that every piglet has different

coping strategies to react to environmental changes. Today’s conventional husbandry systems

could overtax this adaptive capacity of the piglets. Therefore, housing should be adapted

further in a way which meets the demands of natural behaviour in pigs.

Acknowledgments

This project was kindly financed by the Ministry of Energy, Agriculture, the Environment and

Rural Areas, Schleswig-Holstein.

82

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85

GENERAL DISCUSSION

Working hypotheses

The aim of the present thesis was the evaluation of tail-biting behaviour in pigs in order to

gain further information on the causes and the underlying mechanism of this abnormal

behaviour. Therefore, two different experimental set-ups concerning environmental

enrichment and weaning management were carried out under practical conditions. In the first

study, the focus was on the effect of manipulable material provided to piglets. In contrast to

former studies in this research field, the focus was on the farrowing and rearing phase instead

of the fattening period. The assumption was made that a daily provision of raw material from

the second week of life until the end of rearing could help to prevent tail-biting behaviour in

pigs. In the second study, the concern was weaning management since reliable information on

optimal weaning management and its effects is still insufficient. The hypothesis was proposed

that the rearing of siblings and, thus, a renunciation of mixing after weaning can prevent tail-

biting during rearing. The data in both studies were collected with a scoring scheme taking

into consideration both tail lesions and tail losses. Additionally, video observations in the

environmental enrichment study delivered data on the activity behaviour of the piglets at

group level and occupation with the material provided. The focus of the video analysis in the

weaning management study was on manipulative behavioural patterns and the piglets’

behaviour prior to a tail-biting outbreak, thereby providing further information on character

differences at individual level.

Raw material

Nowadays, animal welfare receives more public attention and is widely discussed on farms.

The five freedoms of animal welfare declared by the UK Farm Animal Welfare Council

(FAWC, 1979) are the freedom from hunger and thirst, from discomfort, from pain, injury

and disease, from fear and distress and the freedom to express normal behaviour. Especially

the last point is important regarding the development of behavioural disorders, because barren

environments of intensive housing systems do often not meet the natural demands of the

animals. If the aversive situation for the piglets consists of the absence of a stimulus to release

a specific behaviour (e.g. rooting), exploratory behaviour is the adaptive coping response

86

(Wechsler, 1995). Unsatisfied foraging behaviour could lead to more manipulation of the tail

of a pen mate, resulting in tail wounds as described by Taylor et al. (2010). The results of

Douglas et al. (2012) show that pigs have more optimistic judgement biases in enriched

environments indicative of a more positive affective state. Also, pigs that have spent time in

an enriched environment react more negatively to being subsequently housed in a barren

environment. Several aspects of a realisation of environmental enrichment in intensive

husbandry are discussed below.

A problem in the environmental enrichment study was that in pens housing 24 piglets (two

litters combined) one piglet bowl resulted in a piglet to occupation ratio of 2.4:1, which

implied that not every piglet reached the provided material at the same time. The limited size

of a point source may restrict access to enrichment causing competition, aggression or

restlessness in groups of animals (Van de Weerd et al., 2006). Pigs’ feeding behaviour

follows a synchronic pattern, a reason why a ratio which exceeds 1:1 is unfavourable. Hansen

et al. (1982) showed a clear connection between the frequencies of aggression, tail- and ear-

biting comparing piglets with access to one feeder in comparison to several feeders.

Nevertheless, there were no significant differences regarding tail-biting in the raw material

groups between the pens housing 24 piglets and the pens housing 12 piglets.

A point of discussion should be the fibre length, which was relatively short (about 50 mm) in

both materials. Day et al. (2008) concluded that the number of tail-biting incidents was higher

in groups with short-chopped straw (mostly 1 to 40 mm) in comparison to partially chopped

(mostly 40 to 70 mm) or long fibre straw (mostly over 70 mm). Nevertheless, based on

experiences from other on-farm studies in which long fibre straw (over 70 mm) led to massive

problems with the slurry system the decision was made to find a trade-off between suitable

materials for piglets and intensive housing systems (Van de Weerd and Day, 2009).

Furthermore, the offering scheme per day should be discussed. In the environmental

enrichment study an effort was made to provide the material twice a day, whereas the offering

scheme in the weaning management study was only once per day. In this study, only small

pens were used and the offering scheme was a relief for the stable staff in order to save time.

Nevertheless, the material did often not last throughout the day and empty piglet bowls can

also be seen as a frustrating factor in the pen. Munsterhjelm et al. (2009) concluded that

moderate bedding of farrowing pens reduces agonistic behaviour later in life, although

87

removal of it increases redirected behaviour, including tail-biting. This might have been

problematic in the environmental enrichment study; the piglets from the raw material groups

did not receive alfalfa hay and corn silage during fattening. The results show that piglets

which received raw material from the second week of life until the end of rearing lost their

tails to a larger extent during fattening (20 %) than piglets out of the control groups (5 %).

Thus, as stated by Munsterhjelm (2009), the withdrawal of material provided in former stages

of life can be interpreted as a frustration factor which could have provoked tail-biting in the

subsequent fattening period. Additionally, Day et al. (2002) proved that moving pigs from

previously straw-bedded accommodation to not straw-bedded accommodation increases the

occurrence of adverse pen-mate-directed behaviour.

Moreover, it is important to mention the renewing aspect of raw material provision as

described by Moinard et al. (2003) and Hunter et al. (2001). The material remained of interest

to the animals as long as it was renewed regularly and did not smell like the pen surroundings

or the piglets themselves. This cannot be guaranteed by occupation material which is

permanent available in the pen such as chains, plastic balls or wooden sticks. Wood-Gush and

Vestergard (1991) proved piglets’ preference for novelty when offered a familiar object in

comparison to a novel object. This emphasises piglets’ curiosity and the value of frequent

renewal of manipulable material. Especially dried corn silage seemed to be suitable to

stimulate the exploratory behaviour of the piglets for a certain length of time. This finding

contributes to Studnitz et al. (2007), who concluded that if the material is complex and if it is

changeable as well as destructible, the novelty value will be maintained. Furthermore, if the

materials contain edible parts, the foraging behaviour as well as the curiosity of the pigs will

be stimulated.

Weaning management

The starting point of tail-biting was detected in both studies in the second week after weaning,

which implicates a relation to the weaning process. Martin (1984) defined weaning as the

period when the drop in parental investment per unit time is the largest. Under “natural

conditions” weaning is a gradual process and in piglets is not completed until 10–12 weeks of

age (Lallès et al., 2007). The piglets are taught how to feed and to root and learn to establish

their hierarchy in the group (Oostindjer et al., 2014). In a current study the effect of a

88

prolonged suckling period in a group farrowing system is being tested in order to evaluate

whether the piglets’ behaviour is positively influenced by the longer presence of the sow.

What needs to be evaluated here is whether abnormal behaviour re-surfaces in connection

with the weaning process as in previous studies or at another point of time. Nevertheless, the

abrupt change in housing environment and separation from the sow as well as the

confrontation with unfamiliar pen mates requires a high coping ability of the piglets. Stress

physiology is often called physiology of adaption. Any challenge facing an animal leads to a

modification of the functioning of that animal, and this change prepares the animal to better

cope with further challenges (Veissier and Boissy, 2007). Tail-biting as a stress-induced

behavioural disorder (Sinisalo et al., 2012) is caused by several risk factors which can

accumulate and influence the overall risk of an individual piglet to show abnormal behaviour

(EUWelNet, 2013). Wiepkema and Van Adrichem (1987) described that conflict behaviour

arises during acute stress, whereas chronic stress brings about disturbed behaviour such as

stereotypes. An animal is said to be in a state of stress if it is required to make abnormal or

extreme adjustments concerning its physiology or behaviour in order to cope with the adverse

aspects of its environment and management (Fraser et al., 1975). Coping is defined as a

behavioural response that aims at reducing the effect of aversive stimuli (Wechsler, 1995).

Welfare is defined as the state of physical and mental health resulting from the process of

behavioural and physiological adaptation when coping successfully with environmental

challenges (Puppe et al., 2012). In intensive housing systems, however, the animals often fail

to counteract aversive situations by using these evolved coping strategies, and it is argued that

abnormal behaviour can originate from unsuccessful coping behaviour (Wechsler, 1995).

Both failure to cope with the environment and difficulty in coping are indicators of poor

welfare (Broom, 1991).

Is the weaning process one of the triggering factors which can provoke subsequent tail-biting

behaviour or does the weaning process occupy the piglets with the exploration of new

environmental surroundings, as well as the meeting of new pen mates? Expressing it in more

abstract manner: Are the piglets’ overwhelmed by today’s management practices (such as

regrouping, rehousing…) and do we overtax their adaptive abilities or, have the piglets with

their individual coping strategies which enable them to react to environmental changes

developed such a flexibility that a “standstill”, which is provoked e.g. by barren rearing pens,

89

results in frustration and boredom? Korte et al. (2007) assumed that not constancy or

freedoms, but capacity to change is crucial to good physical and mental health and good

animal welfare.

Underlying mechanisms and coping strategies

Tail-biting occurred in both studies regardless of the treatment groups. The variable results

suggest a connection between the behavioural disorder and the individual character of the

piglets, which was detected by video analysis in the weaning management study. Dantzer and

Mormède (1983) stated that behavioural responses follow two opposite modes, a passive

mode (e.g. freezing) vs. an active mode (e.g. fight/ flight), which (both) depend on the

individual’s genetic background and prior experience. Hessing et al. (1993) found proof of the

existence of behavioural strategies to cope with conflict situations in piglets. Koolhaas et al.

(1999) concluded that there are distinct phenotypes (proactive and reactive coping styles)

which are more or less stable over time in their response to stressors and, thus, may adapt

differentially to environmental conditions. Transferring this assumption to the results of the

video analysis, the coping style of receivers of tail-biting would be classified as passive since

they stop to perform overt behaviour when exposed to an aversive situation and wait for a

change (Wechsler, 1995). Performers on the other hand could be seen as active coping types,

which react to aversive situations with abnormal behaviour. Korte et al. (2009) assumed that

artificial genetic selection (fast growth, leaner meat, larger muscle volume) results in the

production of farm animals that prefer the aggressive hawkish behavioural strategy and, thus,

have a higher risk of developing violence and stereotypes. Nevertheless, focusing on welfare

aspects in breeding, it needs to be kept in mind that breeding against behavioural measures of

welfare could inadvertently result in resilient animals that do not show behavioural signs of

low welfare yet may still suffer (D'Eath et al., 2010).

Prediction of tail-biting events on commercial farms

One part of animal behaviour important for the prediction of tail-biting outbreaks is tail

posture. In the course of both studies, no data on this trait were collected, but direct

observations made during the weekly scoring gave an indication that tail posture is linked

with tail-biting outbreaks. In case of an incidence in a pen, the piglets waved their tails more

90

frequently and piglets which had already received bites, tucked their tails under to prevent

further manipulation. This contributes to the study of Zonderland et al. (2009), who concluded

that a piglet’s tail posture is strongly related to tail damage at the same moment and can

predict tail damage two to three days later. Thus, long tails in piglets can be used as an “early

alert” system, since any management problem which causes tail-biting, such as dysfunction in

feed- or water accessibility as well as climate deficiency, could then be detected.

Another observation that could be made was the piglets’ behaviour when entering the pen in

order to score the tails. In pens with tail-biting outbreaks, the piglets showed different

behaviour towards the observer. This trait was subjectively evaluated and not consequently

documented during the studies. In the case of a tail-biting outbreak, piglets were more

obtrusive, searched contact with the observer more quickly, and manipulated the observer

more frequently. The most possible objective way of assessing this is probably the human

approach test. In this test, a human enters a pen and documents the latency until the piglets

perform their first physical contact with the observer (Brown et al., 2009).

Furthermore, there is evidence that changes in feeding patterns are connected with tail-biting

outbreaks. Wallenbeck and Keeling (2013) showed that low frequencies of daily feeder visits

observed at group level can predict future tail-biting in the pen as early as nine weeks before

the first tail injuries. Therefore, feed consumption could be a parameter which should be

considered in further studies.

Recommendations for further research

In both studies, the animal to feeding place ratio was 2:1, which inhibited stress-free feed

intake for the piglets. An insufficient animal to feeding place ratio increases the risk for tail-

biting (Hansen et al., 1982; Moinard et al., 2003). Evaluations should be carried out as to

whether a ratio of 1:1 has positive effects on the development of the behavioural disorder.

Another aspect could be feed composition (especially crude fibre content) and the dosage

form of feed (liquid vs. dry), since information available in literature is inconsistent.

A further focus should be put on genetics since there is an indication that a higher lean meat

content and decreasing back fat thickness is connected with increasing frequencies of tail-

biting (Moinard et al., 2003). In the last few decades, consumers have shown a growing

interest in higher lean meat content due to fitness aspects, which have resulted in a more

91

targeted selection. It needs to be clarified whether the breeding in turn affected the piglets’

behaviour as mentioned above.

Individuals which showed the obsessive form of tail-biting, as described by Taylor et al.

(2010), could be detected by direct and video observation in both studies. If these animals

tail-biting as a stereotype developed due to chronic stress probably caused by health problems

or malnutrition cannot be sufficiently clarified. A point of interest in identified biters would

be the analysis of blood and brain serotonin measures, which are related to dietary tryptophan

supply and play an important role in stress metabolism (Koopmans et al., 2006). The results

of Ursinus et al. (2013) suggest a role of serotonin in biological traits underlying the

behavioural responses of pigs during a challenging situation.

Moreover, diseases such as infections caused by E. coli and Streptococcus suis occurred in

both studies and probably led to increasing tail-biting behaviour in affected pens and units,

subsequently. There are indications that a proper health status is of crucial importance in the

prevention of tail-biting (Moinard et al., 2003; Walker and Bilkei, 2006); pigs which are

infected may be more reluctant to defend themselves against being bitten (Kritas and

Morrison, 2004). The serum acute phase proteins haptoglobin, respectively C-reactive protein,

as indicators of inflammatory reactions can provide an important marker for swine health

status in further studies (Chen et al., 2003).

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95



GENERAL SUMMARY

The aim of the present thesis was the evaluation of tail-biting behaviour in pigs in order to

gain further information on the causes and the underlying mechanism of this abnormal

behaviour. Therefore, two different experimental set-ups concerning environmental

enrichment and weaning management were carried out under practical conditions.

The focus of the environmental enrichment study was on the effect of manipulable material

provided for long-tailed piglets. In addition to former studies in this research field, the focus

was given to the farrowing and rearing phases instead of the fattening period. Two different

substrates, dried corn silage (SG, n = 245) and alfalfa hay (AG, n = 245) were provided to the

piglets twice per day from the second week of life until the end of rearing. A control (CG,

n = 231) were kept without provision of additional raw material. The focus of the second

study was on weaning management, since reliable information of its effect on tail-biting is

still missing. The hypothesis proposed was that the avoidance of stress through mixing after

weaning has positive effects on the manifestation of behavioural disorders. In total, 478 long-

tailed piglets were divided into two groups, 240 piglets were housed in litter groups (LG),

whereas 238 piglets were mixed at least out of three different litters (MG). The data in both

studies were collected with a scoring scheme regarding tail lesions/ tail losses once per week

with a four-point score (0 = no damage/ original length of tail to 3 = severe damage/ total loss

of tail). In the environmental enrichment study, video observations of 99 piglets during

farrowing and 188 piglets during rearing delivered additional data on the activity behaviour at

group level and the piglets’ occupation with the material provided. The focus of video

observation in the weaning management study was on manipulative behavioural patterns and

piglets’ behaviour prior to a tail-biting outbreak. Recorded video material of five pens (60

piglets) was under analysis by instantaneous scan sampling and continuous observation.

Based on the frequencies of the manipulative behaviour performed, each piglet produced a

character score, which enabled it to be classified as a performer, neutral or a receiver of

manipulative behavioural patterns.

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The results in both studies were similar regarding the tested effect of week after weaning on

tail lesions and tail losses. Tail-biting started on average two to three weeks after weaning,

followed by tail losses one to two weeks later. A finding which can be explained by several

conversions piglets are faced with during the weaning process. Separation from the sow and

adaption to a new environment (social and spatial) contribute to stressful situations for the

piglets. If they fail to cope with these challenges, piglets could develop tail-biting behaviour.

In the environmental enrichment study, the amount of tail losses decreased with the number

of batches (96.4 % in batch one vs. 7.4 % in batch ten). This can be explained by an enhanced

and more precise animal observation by stable staff and points out the learning process in the

course of the study. Piglets out of all batches lost their tails to the greatest extent in CGs

(50.4 %), followed by AGs (49.2 %) and SGs (30.2 %) at the end of rearing. Curative

measures were also carried out in CGs to avoid severe injuries and welfare problems in the

case of tail-biting outbreaks. Thus, CGs were falsified, which could have led to an

approximation of raw material groups and control groups. The number of tail lesions and tail

losses in the weaning management study differed without a clear trend between the treatment

groups and the batches. This finding could be explained by the different forms of tail-biting.

Two stage tail-biting is longer lasting than sudden forceful tail-biting, thus, the first form was

probably detected more securely during weekly scoring. Furthermore, dysfunctions in water

or feed accessibility or climate variations within the units could have provoked behavioural

disorder. The daily weight gain of the piglets showed no clear trend over treatment groups and

batches and could not be connected with the weekly scoring of tail lesions and tail losses in

both studies.

Corn silage stayed attractive for the piglets during the whole observation period in the

environmental enrichment study, whereas the acceptance of alfalfa hay decreased towards the

end of rearing. This could be explained by a better palatability of corn silage due to higher

concentrations of carbohydrates and lower dry-matter content. There was no clear trend

between activity behaviour and the level of tail-biting within the batches. The pen mate-

directed behaviour tail exploration in the weaning management study increased over five days

prior to a scored tail-biting outbreak. The frequencies of belly nosing were highest in the pen

which was observed closest to weaning, which indicates a connection to the weaning process.

The receivers of nosing behaviour lay more frequently than the performers, thus, they reacted

97

less defensively and tolerated manipulations with the snout more frequently, whereas

performers showed higher general activity.

A provision of raw material from the second week of life until the end of rearing and a

renunciation of mixing after weaning cannot prevent tail-biting during rearing. Rearing of

long-tailed pigs requires intensive animal observation and direct intervention in the case of

tail-biting outbreaks, provision of raw material as manipulable material is useful. There were

clear differences in individual pig characters and it needs to be taken into account that every

piglet has different coping strategies to react to environmental changes. Today’s conventional

husbandry systems could overtax this adaptive capacity of the piglets. Therefore, housing

should be adapted further in a way which meets the demands of natural behaviour in pigs.

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Zusammenfassung

Das Ziel der vorliegenden Dissertation war die Evaluierung von Schwanzbeißverhalten beim

Schwein um weitergehende Informationen über die Ursachen und zugrundeliegenden

Mechanismen des Fehlverhaltens zu erlangen. Hierfür wurden unter Praxisbedingungen zwei

verschiedene Studien mit den Schwerpunkten Beschäftigungsmaterial und

Absetzmanagement durchgeführt.

Der Fokus der ersten Studie lag auf dem Effekt von manipulierbarem Material für unkupierte

Schweine. Im Gegensatz zu früheren Studien in diesem Forschungsgebiet wurden die Säuge-

und Aufzuchtsphase, anstelle der Mastperiode untersucht. Zwei verschiedene Materialien,

getrocknete Maissilage (SG, n = 245) und Luzerneheu (AG, n = 245) wurden den Ferkeln

zweimal täglich von der zweiten Lebenswoche bis zum Ende der Aufzucht angeboten. Eine

Kontrolle (CG, n = 231) wurde ohne zusätzliches Beschäftigungsmaterial gehalten. Der Fokus

der zweiten Studie lag auf dem Absetzmanagement, weil zuverlässige Informationen zum

Einfluss auf Schwanzbeißen fehlen. Es wurde die Hypothese aufgestellt, dass die Vermeidung

von Stress durch Mischen nach dem Absetzen positive Effekte auf die Manifestierung von

Verhaltensstörungen hat. Insgesamt wurden 478 unkupierte Ferkel in zwei Gruppen geteilt,

240 Ferkel wurden wurfweise aufgestallt (LG), während 238 Ferkel aus mindestens drei

Würfen gemischt wurden (MG). In beiden Studien wurden die Daten mit Hilfe eines

Boniturschemas wöchentlich aufgenommen, dabei wurden Schwanzverletzungen

und -verluste durch einen vierstufigen Schlüssel bewertet (0 = keine Verletzungen/

Originallänge bis 3 = großflächige Verletzung/ Komplettverlust des Schwanzes). In der Studie

zum Beschäftigungsmaterial wurden zusätzlich Videobeobachtungen von 99 Ferkeln in der

Säugephase und 188 Ferkeln in der Aufzucht erhoben und lieferten Daten über das

Aktivitätsverhalten auf Buchtenebene und die Beschäftigung der Ferkel mit dem angebotenen

Material. Der Fokus der Videobeobachtungen in der Absetzmanagementstudie lag auf

manipulativen Verhaltensweisen und dem Schweineverhalten vor einem

Schwanzbeißausbruch. Aufgenommenes Videomaterial von fünf Buchten (60 Ferkel) wurde

mittels „Instantaneous scan sampling“ und kontinuierlicher Beobachtung ausgewertet. Auf

99

der Grundlage der Häufigkeiten des ausgeübten manipulativen Verhaltens erhielt jedes Ferkel

einen Charakterschlüssel, welcher eine Klassifizierung in Ausführender bzw. Empfänger von

manipulativen Verhaltensweisen oder neutraler Charakter ermöglichte.

Der Effekt der Woche nach dem Absetzen auf Schwanzverletzungen und –verluste war in

beiden Studien ähnlich. Schwanzbeißen begann im Schnitt zwei bis drei Wochen nach dem

Absetzen, gefolgt von Schwanzverlusten ein bis zwei Wochen später. Eine Erkenntnis, die

durch verschiedene Veränderungen erklärt werden kann, mit der die Ferkel durch das

Absetzen konfrontiert sind. Die Trennung von der Muttersau und die Anpassung an eine neue

Umgebung (sozial und räumlich) tragen zu einer belastenden Situation für die Ferkel bei.

Falls es ihnen nicht gelingt, diese Herausforderungen zu bewältigen, könnten die Ferkel

Schwanzbeißverhalten entwickeln. In der Studie zum Beschäftigungsmaterial nahm die Zahl

der Schwanzverluste mit der Anzahl der Durchgänge ab (96.4 % im ersten Durchgang vs.

7.4 % im zehnten Durchgang). Dies kann durch eine verbesserte und präzisere

Tierbeobachtung durch das Stallpersonal erklärt werden und stellt einen Lernprozess im

Verlauf der Studie dar. Ferkel aus allen Durchgängen hatten die meisten Schwanzverluste am

Ende der Aufzucht in CGs (50.4 %) zu verzeichnen, gefolgt von AGs (49.2 %) und SGs

(30.2 %). Kurative Maßnahmen wurden im Falle von Schwanzbeißausbrüchen auch in CGs

durchgeführt, um schwerwiegende Verletzungen und Einschränkungen des Tierwohls zu

vermeiden. Dementsprechend wurden CGs verfälscht, was möglicherweise zu einer

Annährung von Raufuttergruppen und Kontrollgruppen geführt hat. Die Zahl der

Schwanzverletzungen und -verluste in der Absetzmanagementstudie unterschieden sich ohne

einen deutlichen Trend zwischen den Versuchsgruppen und den Durchgängen. Diese

Feststellung konnte durch die verschiedenen Formen von Schwanzbeißen erklärt werden.

„Zweistufiges Beißen“ stellt einen länger andauernden Prozess dar als „plötzlich-gewaltsames

Beißen“; möglicherweise war die erste Form dadurch sicherer durch die wöchentliche Bonitur

festzustellen. Darüber hinaus könnten Ausfälle in der Wasser- und Futterversorgung oder

Veränderungen im Abteilklima die Verhaltensstörung ausgelöst haben. Die täglichen

Zunahmen folgten keinem klaren Trend über die Versuchsgruppen und die Durchgänge und

konnten in keiner der beiden Studien mit der wöchentlichen Bonitur von

Schwanzverletzungen und –verlusten in Verbindung gebracht werden.

100

In der Studie zum Beschäftigungsmaterial blieb Maissilage während der gesamten

Beobachtungsperiode attraktiv für die Ferkel, während die Akzeptanz von Luzerneheu gegen

Ende der Ferkelaufzucht abnahm. Dies könnte mit einer besseren Schmackhaftigkeit der

Maissilage durch eine höhere Konzentration von Kohlenhydraten und einem geringeren

Trockenmassegehalt erklärt werden. Es konnte kein klarer Trend zwischen dem

Aktivitätsverhalten und dem Schwanzbeißniveau innerhalb der Durchgänge festgestellt

werden. Das gegen Buchtengenossen gerichtete Verhalten “Tail exploration” in der

Absetzmanagementstudie stieg fünf Tage vor einem bonitierten Schwanzbeißausbruch an. Die

Häufigkeiten von „Belly Nosing“ waren am höchsten in der Bucht, die am nächsten zum

Absetzen beobachtet wurde, was eine Verbindung zum Absetzprozess vermuten lässt. Die

Empfänger von „Nosing“ lagen häufiger als die Ausüber dieses Verhaltens, dementsprechend

reagierten sie weniger defensiv und tolerierten die Manipulationen mit der Schnauze häufiger,

während die Ausführenden eine höhere Gesamtaktivität zeigten.

Ein Angebot von Raufutter ab der zweiten Lebenswoche bis zum Ende der Ferkelaufzucht

und ein Verzicht auf das Mischen von Würfen nach dem Absetzen kann Schwanzbeißen nicht

verhindern. Die Aufzucht von unkupierten Schweinen erfordert eine intensive

Tierbeobachtung und sofortiges Eingreifen im Falle von Schwanzbeißausbrüchen, das

Angebot von Raufutter, als manipulierbares Material, ist von Nutzen. Es gab klare

Unterschiede im individuellen Charakter der Schweine und es muss beachtet werden, dass

jedes Ferkel verschiedene Bewältigungsstrategien besitzt, um auf Änderungen seiner Umwelt

zu reagieren. Die heutigen Haltungssysteme könnten diese Anpassungsfähigkeit der Ferkel

überfordern. Demnach sollten die Haltungsbedingungen weiter angepasst werden, um

Schweinen ein Verhalten zu ermöglichen, das ihren natürlichen Bedürfnissen entspricht.

101

Lebenslauf

Persönliche Daten

Name: Christina Maria Veit

Geburtsdatum: 17. Oktober 1987

Geburtsort: Neunkirchen/Saar

Staatsangehörigkeit: deutsch

Berufliche Tätigkeiten

09/2013 - 02/2016 Wissenschaftliche Mitarbeiterin

Institut für Tierzucht und Tierhaltung

Christian-Albrechts-Universität Kiel

Studium

10/2007 - 03/2013 Studium der Veterinärmedizin

Stiftung Tierärztliche Hochschule Hannover

11.06.2013 Approbation als Tierärztin

Schulische Ausbildung

08/1998 - 06/2007 Arnold-Janssen-Gymnasium St. Wendel

102

Danksagung

Mein herzlichstes Dankeschön gebührt meinem Doktorvater Prof. Dr. Joachim Krieter, der

mich während der gesamten Dissertation unermüdlich unterstützt hat.

Danken möchte ich auch Frau Prof. Dr. Elisabeth große Beilage für die Übernahme der

Betreuung seitens der Tierärztlichen Hochschule Hannover.

Weiterhin möchte ich Imke Traulsen danken, die vor allem in Statistikfragen viel Geduld

bewiesen hat. Auch Irena Czycholl und Kathrin Büttner haben durch ihre Unterstützung

maßgeblich zum Gelingen der Arbeit beigetragen.

Außerdem möchte ich mich herzlich bei allen Mitarbeitern des Lehr- und Versuchszentrums

Futterkamp für die angenehme Zusammenarbeit bedanken.

Ein ganz besonderer Dank geht an die Mensa-Crew Julia, Charlotte und Birte und an meine

Wohngemeinschaft, die Kiel zu etwas ganz Besonderem für mich gemacht hat. Vielen Dank

für die gute Zeit!

Mein allergrößtes Dankeschön gilt meiner Familie, meinem Partner und meinen Freunden, die

mich in allen Lebenslagen tragen und an mich glauben. Ohne euch wäre ich nie so weit

gekommen!

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