Effects of fleece soiling and skinning method on the microbiology of sheep carcases

Abstract

The fleece of sheep becomes soiled primarily on the abdomen and on the legs. A five-category scoring scale for soiling of the fleece was defined, with score 1 being clean and dry and score 5 being wet and heavily soiled with faecal material. Twenty sheep with each fleece score were slaughtered and dressed on a commercial 'inverted' slaughter line. Swab samples were taken from the shoulder and the abdomen of the carcases immediately after skinning, and total viable counts and the numbers of Enterobacteriaceae were determined. The condition of the fleece significantly affected the microbial load on these parts of the dressed carcase, with the carcases derived from sheep with increasingly dirty fleeces carrying up to 1000 times more microorganisms, and a higher proportion of the carcases being contaminated with Enterobacteriaceae. Modifications to the dressing procedure were made to try to reduce carcase contamination at the shoulder. The application of bulldog clips to prevent direct contact between the fleece and the underlying muscles resulted in higher counts on carcases with a fleece score of 3, probably owing to contamination from the hands of the slaughterman and the problems with ensuring that the clips were in place before contamination had occurred. Delaying the skinning of the shoulder until later in the pelt removal process achieved worthwhile reductions in the contamination of the shoulder of carcases with a fleece score of 4, although the total viable counts were still higher than carcases with a score of 3.

Review of the impact of pre-slaughter feed curfews of cattle, sheep and goats on food safety and carcase hygiene in Australia

“…In Finland special hide regulations have been in place since 1982 (Ridell & Korkeala, 1993) resulting in a substantial 85% reduction in the 'incoming problem' with a mean 0.7 log cfu/cm 2 less TVC on carcases from control cattle when compared with those from excessively dirty cattle. In sheep, Hadley et al (1997) demonstrated a mean 3 log cfu/cm 2 difference in carcase TVC between carcases from sheep with fleece soiling score 1 and 5 when carcases were sampled immediately after fleece pulling. While these latter authors propose that such a scoring system could be used within a price weighting structure at purchase, in Australian sheep abattoirs a range of mitigations are practiced including only accepting crutched sheep at the lairage, crutching at the abattoir as required and use of additional slaughter-line staff to maintain dressing hygiene (Kiermeier, Jenson, & Sumner, 2009).…”

“…There was also no association whether the lambs were crutch-shorn or not. However, Hadley, Holder, and Hinton (1997) found that hygiene indicator counts were 2 log units higher on carcases from extensively soiled and wet 10 month old unshorn sheep, when compared with those from clean and dry four month old lambs. Thus it appears that 'spring lambs', reared and transported under conditions that avoid soiling of the fleece, can provide carcases of superior microbiological condition (Gill, 2004).…”

“…These are based on scoring the dirtiness of hides and fleeces and have been developed for research and pre-regulatory evaluation (Collis et al, 2004;Davies, Hadley, Stosic, & Webster, 2000;Hadley et al, 1997;Jordan, McEwen, Wilson, McNab, & Lammerding, 1999;McEvoy et al, 2000) and regulatory use (Ridell & Korkeala, 1993). Jordan et al (1999), in evaluating the reliability of five cattle "faecal dag" rates, demonstrated a high degree of correlation between the rates at both the individual and lot level in lot-fed cattle.…”

Scientific Opinion on a summary of scientific studies undertaken by the UK Food Standards Agency to support a proposed production method for smoked “skin-on” sheep meat

“…Bacterial pathogens previously reported include Salmonella (Duffy et al, 2000;Sierra et al, 1995;Smith and Grau, 1973), E. coli O157:H7 (Chapman et al, 2001;Chapman et al, 1996), Listeria (Antoniollo et al, 2003), Campylobacter (Stanley and Jones, 2003;Stanley et al, 1998), Clostridium perfringens (Grau et al, 1986) and Yersinia (Antoniollo et al, 2003). The role of the hygienic status of fleece in the contamination of the carcass with pathogens was identified by several authors (Bell and Hathaway, 1996;Biss and Hathaway, 1995;Hadley et al, 1997), and was also discussed in a past EFSA Opinion (EFSA, 2004). Biss and Hathaway (2011) indicate that HACCP-based systems can significantly reduce microbiological contamination of sheep carcasses, with possible CCPs being pre-slaughter presentation status (including avoidance of preslaughter washing), inverted dressing, handling by slaughterline workers and meat inspectors, and chilling.…”

Current practices on sheep and beef farms in New Zealand for depriving sheep of feed prior to transport for slaughter

“…Deprivation usually commences prior to transport to empty the gastrointestinal and urinary tracts to reduce defaecation and urination. This reduces the accumulation of effluent during transport, the risk of carcass microbial contamination during slaughter (Grau and Smith 1974;Biss and Hathaway 1996;Hadley et al 1997), and facilitates more hygienic evisceration (Petersen et al 1981).…”