Farm-to-slaughter phase: microbial contamination in cattle

and beef

Sava BuncicProfessor in Meat Hygiene and Safety

University of Novi Sad (Serbia)

Summary

Contamination (using example of E. coliO157) in cattle:

- On-farm

- Transport

- Lairaging

- Slaughter- Control strategies

E. coli O157 in cattle during on-farm phase

Summary of published prevalences of E. coliO157 in cattle on-farm (Avery & Buncic, 2005)

On hides:18.0%

On surfaces24.6%

In faeces:Average: 8.3% (0.5-22.7%)

Median: 5.5%

On-farm controls of E. coli O157

Other controls?

Modifications of the host responses- Vaccination

Suppresion of the ingested pathogen:- Dietary manipulation

- Probiotics- Phage therapy

Prevention of the ingestion of the pathogen:- Feed treatments- Water treatments

- Animal interactions (suckling, licking)

Prevention of the pathogen's recycling- Land management (animal wastes)

- Vectors (rodents, wildlife...)- Animal husbandry (GHP)

E. coli O157 in cattle during transport-lairaging phase

Risk factors during transport-lairaging: stress

• In cattle faeces: Salmonella increased but E. coli O157 decreased (Barham et al., 2002; Minihan et al., 2003)

• On cattle hides: both Salmonella and E. coli O157 increased during transport (Barham et al., 2002)

• A transportation controversy: E. coli O157 in faeces versus hide?

• Possible: stress-mediated increased defecation leading to:– increased E. coli O157 hide contamination; – elimination of E. coli O157 cells from colon content

(those not attached to the epithelium).

Risk factors during transport-lairaging: other

• Animal versus animal groups– Groups with E. coli O157 >20% have higher hide

contamination (Woerner et al., 2006)

• Duration– The longer transport-lairaging the higher E. coli

O157 hide contamination (Dewell et al, 2008)

• Inefficient cleaning of vehicle/lairage surfaces– E. coli O157:H7 on 64%, and Salmonella spp. on

71% of ”cleaned” surfaces (Arthur et al., 2008)

Risk factors during transport-lairaging: other

• Survival of pathogens on surfaces – Can lead to pathogens’ accumulation and/or

carryover of contamination between days (Small et al., 2002, 2003)

• Animal activities and interactions– Contribute to cross-contamination (Small & Buncic,

2009)

Summary of published prevalences of E. coliO157 in cattle during transport-lairage phase

(Avery & Buncic, 2005)

On transport vehicles' surfaces:7.3%

On surfaces in lairages:Average: 21.5%

(6.7-50.0%)

In faeces after transport:Average: 7.4%

(1.7-13.0%)

Contamination of surfaces in cattle lairages(Small et al., 2002)

Crush

RaceStun Box

Holding Pen

UnloadingFunnel

Water TroughE. coli O157

Salmonella

Campylobacter

Survival (D25oC-values, days) of Escherichia coli O157 on contaminated transport- or lairage-related substrates

(Small et al., 2002)

02468

101214161820

Straw Hide Metal Concrete

Faecal Non-faecal

Average survival rates of E. coli O157 isolates (n=123) on concrete during 24 h (Avery & Buncic, 2003)

Human (n = 31) 15.3%

Meat (n = 29) 27.7%

Animal faeces (n = 32) 26.0%

Hides (n = 31) 22.9%

Average contacts per bovine in lairageover 30 minutes by space allowance

(Small & Buncic, 2009)

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total contacts wall contacts animal contacts

Possible cross-contamination between 8 cattle in a pen, if 50% transfer rate (Small & Buncic, 2005)

Marker-organisms in cattle during lairaging (Collis et al., 2004)

PFGE fingerprint found on hide of slaughtered cattle from different farms and lairage pens (Avery et al., 2002)

6 (X2)13 (X2)37 (X4)58 (X2)

5 (X1)12 (X2)19 (X2)21 (X2)45 (X2)

8 (X2)38 (X4)45 (X2)

16 (X1)34 (X3)

17 (X2)57 (X2)

45 (X5)10 (X2) 26 (X2)49 (X2) 47 (X2)40 (X3)50 (X2)72 (X2)

Cattle from lorries via two unloading ramps

Rail to sticking and sampling station

Race to stunning

Stunning box

Other molecular studies of hide/carcass E. coli O157 and Salmonella also demonstrated their transport-lairage origin (e.g. Tutenel et al., 2003; Childs et al., 2006; Arthur et al., 2007, 2008; Dewell et al., 2008).

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P S47

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P S49

E. coli O157 in cattle during slaughter phase

→

Faeces-hide-meat relationship of E. coli O157 during dressing phase

(Avery & Buncic, 2005)

On hide at dressing:Average: 24.8% (4.5-56%)

Median: 23.6%

In faeces at evisceration:Average: 9.3%Median: 7.5%

On carcasses:Average: 12.9% (1.1-43.4%)

Median: 8.9%

General microflora on hides of slaughtered cattle (overall literature data)

5.51.74.2GenericE. coli

5.94.04.5Coliforms

6.02.94.1Enterobacteriaceae

10.54.56.3Total viable count - TVC

ToFromAveragelog cfu/cm2

Counts of organisms

Pathogens on hides of slaughtered cattle(overall literature data)

47.90(scarce dataListeriamonocytogenes

130(scarce data)Campylobacter

100050.3(fewer data)

Salmonella

100045.8(much data)

E. coli O157

ToFromAverage%

Prevalence of organisms

Microbial distribution on hides• Overall microbial loads (TVC):

– visually “dirty” hides: 6-10 log cfu/cm2

– visually “clean” hides: 4.5-8 log cfu/cm2

• Pathogen load: E. coli O157 between 2-3 cells/cm2 (Arthur et al., 2004; 2007) and 2-3 log cfu/cm2 (O’Brien et al, 2005; Arthur et al., 2004)

• Location of microflora on hide:– “horizontally”: feet (metacarpus)>brisket>rump>flank

(Nastasijevic et al., 2008; Antic et al., 2008, unpublished)

– “vertically”: no major differences between upper and lower layers of the hair (Antic et al., 2008, unpublished).

Microbial attachment on hides

• Attachment of microorganisms to hair:– dirt: contains much bacteria, but if hardened -

physically “encapsulates” them;– water increases “removable” portion of microflora;– some products of skin glands (e.g. free

monosacharids) diminish bacterial attachment to epidermal cells (Meyer i sar. 2001);

– bacterial attaching “affinity” to hide stronger than to meat (?).

Microbial transfer from hide onto carcass

• Small proportions of hide microflora transferred onto meat:

– via direct contact, experimentally, between 0.1% and 0.0004% (Antic et al., 2008, unpublished);

– via all routes together, commercially, between 1.6% and 0.003% (Bacon et al., 2000; Vivas Alegre & Buncic, 2004; Arthur et al., 2004); but

• High occurrence on hide + regular transfer = high risk of pathogens contaminating meat

Microbial transfer from hide onto carcass

• Therefore, hide-to-meat transfer of pathogens must be:

– totally prevented during skinning by hygiene(but is unachievable);

OR

– eliminated from hide before skinning by treatments(seems possible).

Transport-lairage (pre-dressing) controls of E. coli O157:H7

Hide decontamination:-After death but before skinning

Minimise between-batches transfer:- Efficient sanitation of pens

- Sanitation of stun-box after each animal?

Miminimise lairaging time:- Accumulation of the excreted pathogen

- Environment-mediated cross-contamination- Lying on contaminated floor

Avoid livestock markets:- Mixing of animals from different farms

- Environment-mediated cross-contamination

Hide decontamination treatments

Global meat safety context of decontamination approaches

• Carcass (meat) decontamination: – reactive, deals with “consequences”; – limitations of treatments (edible; meat quality & safety

concerns) limit the efficacies

• Hide decontamination: – proactive, deals with “causes”; – much harsher treatments possible (inedible)

• Either-or versus both

Change in TVC (log cfu/cm)

-3-2.5

-2-1.5

-1-0.5

00.5

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Decontamination treatment

log

chan

ge

Decontamination of hides (Small et al., 2004):

1. Water at 50°C; 2. Water at 50°C plus dry,

3. Water at 50°C plus food-safe detergent; 4. Water at 50°C plus food-safe detergent plus dry.

5. Water at 50°C plus food industry approved disinfectant; 6. water at 50°C plus food industry approved disinfectant plus dry.

7. Water at 50°C plus food industry approved quaternary ammonium sanitizer; 8. Water at 50°C plus food industry approved quaternary ammonium sanitizer plus dry

9. Clipping the hair; 10. Clipping and singeing.

Microbial-immobilisation treatments of hide: general microflora (Antic et al., 2008, unpublished)

4.90Antisept G rinse-vacuum(comparative “control”)

3.40Hair spray (commercial)

6.566.56Shellac, 23% in ethanol(an insect-produced natural resin)

TVC reductions(log CFU/cm2)

Treatments

Microbial-immobilisation treatments of hide: pathogens (Antic et al., 2008 , unpublished)

2.1 2.1 log CFU/cm2log CFU/cm2Inoculated hide: with E. coliO157

3.7 3.7 --foldfoldUninoculated (natural) hide:E. coli O157 prevalence

E. coli O157 reductionsHides

Very grateful to my younger associates for the research work!

Bristol University (UK):

Carol-Ann WilkinAlison SmallSheryl Avery

Luis Vivas AlegreSilvia Nicolau

Novi Sad University (Serbia):

Dragan AnticBojan BlagojevicMiroslav Ducic

Ivan NastasijevicRadmila Mitrovic