Farm-to-slaughter phase: microbial contamination in cattle ... · Farm-to-slaughter phase:...
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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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0 2 4 6 8 10 12
space allowance (sqm)
num
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f con
tact
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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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9080706050403020 180
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4.0
0E3
4.5
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5.0
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5.5
0E3
6.0
0E3
7.0
0E3
8.0
0E3
9.0
0E3
1.2
0E4
1.5
0E4
2.0
0E4
2.5
0E4
3.0
0E4
P S47
P S48
P S1
P S2
P S3
P S4
P S5
P S8
P S6
P S9
P S7
P S15
P S16
P S17
P S18
P S19
P S20
P S22
P S50
P S51
P S52
P S10
P S11
P S12
P S13
P S14
P S21
P S23
P S24
P S27
P S28
P S29
P S30
P S26
P S31
P S32
P S33
P S34
P S35
P S36
P S37
P S38
P S39
P S43
P S44
P S40
P S41
P S46
P S42
P S45
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
1
1 2 3 4 5 6 7 8 9 10
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