Post on 26-Jan-2017
transcript
Group formation and mixing times for gestating sows
Jennifer Brown, PhDPrairie Swine Centre
Saskatchewan
Outline
• Introduction: sows in groups• When to mix?– Early vs late
• Group composition–Uniform vs mixed parities
• Other considerations…– Socialization, group size, electronic
data
WHO LET THE SOWS OUT???
Introduction• Increasing regulation of gestation housing– EU: 2013 stall use permitted up to 4 weeks– Netherlands: stall use up to 5 days– UK, Sweden: no stall housing – Canada: stall use limited in new or renovated
barns (2014), added restrictions in 2024
• Voluntary changes- incentives for branded products
• Packer and retailer demands
When to mix?• Aggression commonly occurs when sows are
mixed
• Concerns over aggression: effects on sow welfare & productivity (Einarrson et al, 2008; Soede et al, 2007)– Injury & lameness– Disruption of estrus expression– Impact of stress on conception rate, litter size
• Implantation (1-4 weeks)– sensitive time for mixing
Mixing: Post-breeding
• Sows commonly mixed at confirmation of pregnancy (21-35 days)- Stall use allows close management from breeding to implantation- Monitor estrus, feed consumption, breeding, preg checking- Mixing aggression delayed until after implantation
But: • Potential for impact on pigs in the pre-natal environment?• What if stall use becomes more restricted?
Mixing: At Weaning
• At weaning- Mixing aggression resolved before estrus/implantation- Evidence that early mixing helps to bring sows onto heat (Pearce and
Hughes, 1992) - Sow-to-sow contact may help to synchronize estrus
Concerns: • Estrus behaviour (mounting) may lead to injury & lameness
• Mixing aggression may disrupt return to estrus, or inhibit estrus expression (eg in subordinate sows)
• Added work- concerns re handling sows at breeding
Mixing studyMethods:• Three treatments, tested over six replicates:– Early Mixing (EM): Sows mixed directly at weaning– Late Mixing (LM): Sows mixed 35 d after breeding
(Control treatment)– Pre-socialization (PS): Sows mixed at weaning for 48hrs,
then put in stalls for breeding– Remixed at 35 d
• Collaboration with Dr. Y. Li, University of Minnesota
Housing system
16 stalls
16 stalls
• Free-access stalls- 14 sows/pen• Gilts and mixed parity sows• 24 ft2/sow (in loafing area)• Stalls used for feeding- otherwise locked out
Study pen
Data Collection• Behaviour at mixing
– Days 1, 2: Aggressive encounters, threats (12h/day)– Days 1-4: Sexual behaviour (EM treatment)
• Sow condition and injury– Body condition score (1-5), weight, back fat
– At weaning, weeks 5 and 16– Skin lesion score, gait score (0-3)
– Before & 48h after mixing
• Sow productivity– Wean-to-service interval– Conception rate (%)– Farrowing performance
Aggression at mixing
Treatment Behavior EM PS1 LM P
Frequency of aggressive interactions (days 1 and 2) 208 213 212 0.993Percentage (%) of time in aggression (day 1) 3.20 2.54 3.55 0.637
Percentage (%) of time in aggression ( days 1 and 2) 2.09 1.89 2.34 0.853
Aggressive interactions, days 1 and 2 (per group of 14 sows)
Saliva cortisol EM PS LMn 24 24 24Baseline 6.54 ± 2.58 5.46 ± 0.94 5.21 ± 0.4524hrs 7.48 ± 2.96 6.87 ± 2.21 .72 hrs 7.76 ± 3.48 5.66 ± 1.07 .24hrsWk5 . 5.51 ± 1.09 6.96 ± 3.1072hrsWk5 . 7.11 ± 5.38 6.88 ± 2.41
nmol/L ±SD, four sows/group
Conception rate (%)
Early Mixing Late Mixing Pre-socialization50
55
60
65
70
75
80
85
90
95
100
b
a
b
98 87 94
• LM sows had significantly lower conception• No difference in returns or sow removals
Performance
• Fewer stillborn piglets in EM treatment
TreatmentItem Early Mixing Pre Socialization Late Mixing P val
Total born 15.2 ± 0.4 15.6 ± 0.4 15.5 ± 0.4 0.700
Born Alive 13.7 ± 0.4 13.3 ± 0.4 13.2 ± 0.5 0.691
Stillborn 0.95a ± 0.12 1.54b ± 0.16 1.58b ± 0.16 0.003
Mummies 0.47 ± 0.09 0.44 ± 0.09 0.53 ± 0.09 0.766
n = 84 sows/ treatment
• Under PSC conditions– early mixing did not affect sow performance
• Better conception in EM and PS vs LM Control– Clearer estrus expression/more pronounced heat?
• Fewer stillborn piglets in EM sows – Benefits of early mixing?
Multiple options: • Producers can select the option that suits their
system • Early mixing can reduce space requirements
for barn conversions• Mixing post-insemination: study ongoing-
common in ESF, combined with automated heat detection
Sow mixing conclusions
• Within ESF systems, low-ranking sows are known to:– Receive more aggression and injuries – Have poorer productivity – Feed later in the daily feeding cycle – Be more frequently displaced from the entry
• Already common to house gilts separately during gestation
Grouping sows in ESF
Grouping sows in ESF
• Objective: Study sow groupings in a static ESF to assess effects on feeding behavior, sow injury and production
– Collaboration with Dr L. Greiner, Innovative Swine Solutions, Illinois
– 6,000 sow herd– Nedap feeding stations– Static groups: 60 sows per group– Recovering from PRRS outbreak
Grouping sows in ESF
• Four treatments – (six replicates x60 sows= 1440 total)
• Sows distributed among treatments each week:
1. Mixed parity –Control (parities 2-7) 2. Low parity (parities 1- 3)3. Medium (parities 3-7)4. High parity (parities 4-8)
Feeding behavior
ESF stations can (theoretically) provide individual sow data on:• Entry order• Feeding time, duration• Recycling- repeated visits per day
• Example: younger sows eat later in the cycle (Strafford et al. 2008)
• Potential for study of social dynamics, effects of hierarchy
Time spent feeding
Mixed Low Medium High0:10:00
0:12:00
0:14:00
0:16:00
0:18:00
0:20:00
0:22:00
EarlyMidLate
Dai
ly F
eedi
ng D
urat
ion
(min
) *
Feeding time (min per sow) in early, mid, and late gestation
Production
Variable
Treatment
PMixed Low Medium High
Stillborn 0.63a 0.40b 0.55ab 0.81a <0.005Piglet mortality 1.19a 1.14a 1.51ab 1.83b <0.001Full value weaned 9.92a 10.22a 10.00ab 9.37b <0.005
• High parity groups had poorest reproduction• Reflects effects of parity, not necessarily treatment• Sows most productive between parities 3 to 6 • Treatments did not significantly affect reproduction
Backfat (change wks 5-15)
1 2 3
-5
-4
-3
-2
-1
0
1
2
3
MixedLowMediumHigh
Parity score
chan
ge in
sow
bac
kfat
(m
m)
*
*
Interactions within parity score (n = 262)
Young sows in Mixed treatment lost 4mm
Sow lameness
Observation period
Treatment
PMixed
(control) LowMediu
m HighPre-mixing to day 3 0.228 a 0.068b -0.015bc -0.09c <0.01Pre-mixing to day 7 0.173a 0.039b 0.001b
0.055b 0.05
• Highest lameness in Mixed parity treatment• Negative values indicate a reduction in lameness• Medium and High had improved locomotion day 3
Change in lameness following mixing (Score: 0 to 4)
Lesion score
Observation period
TreatmentPMixed
(control)
Low Medium High
Premixing to day 5 5.84b 6.90a 6.52ab 3.83c <0.00
1
Change in lesion scores following mixing
• Younger sow groups displayed more aggression, received more skin injuries
Conclusions: Sow grouping
• It is already a common practice to house gilts separately during gestation
• Low parity sows can also benefit from segregation– Increased backfat– Reduced lameness after mixing
Other considerations…
• Mixing post insemination– Integrates well with ESF systems– Reduce stall space requirements– Repeats can be detected automatically
• Large groups– Flexible: Static or dynamic, batch farrowing– Space to avoid conflict– Sows adopt more passive social behavior
Automation…
Acknowledgements• Specific project funding provided by:
National Pork Board
• Strategic funding provided by:
Questions?
Parity Score SEM
P
1 2 3Treatment Treatment Treatment
Mixed Low Mixed Low Medium HighMixe
d Medium High
-4.12a 0.22bc -0.45bc 0.99c 0.87c 0.50bc 0.17bc 1.99bc -0.64b 1.29 <0.05
Changes in sow backfat (mm) from entering the gestation pen (5 weeks) to 15 weeks, showing interactions among treatments within parity score (n = 262).
Within parity score, where superscripts differ, P<0.05
Backfat (change wks 5-15)