MICROBIOLOGICAL CONTAMINATION OF OVINE CARCASSES ASSOCIATED WITH THE PRESENCE OF WOOL AND FECAL MATERIAL

The microbiological contamination of ovine hind legs at sites which we re visibly clean (control carcasses), sites immediately adjacent to an d below visually contaminated sites, and sites contaminated with visib le faecal material or wool were determined by excision sampling immedi ately after pelting and immediately after a pre-evisceration wash. The mean aerobic plate count (APC) and Escherichia coli count (EC) at cle an sites immediately after pelting ranged from log(10) cm(-2) 3.98 to 4.44 and log(10) cm(-2) 0.96 to 1.51, respectively. These levels of co ntamination were significantly lower than those on sites contaminated with faecal material (log(10) cm(-2) 6.00 and 3.00, respectively) or w ool (log(10) cm(-2) 5.44 and 2.45, respectively). The presence of faec al material or wool on the carcass was not associated with increased b acterial numbers on visually clean areas of the carcass. This indicate s that the presence of faecal material or wool alone cannot be used as an indicator of the hygienic status of the carcass as a whole, partic ularly in the role of on-line monitoring parameters for HACCP systems. Pre-evisceration washing of carcasses had very little effect on the u ncontaminated areas of the carcasses, but reduced the mean APC and EC at the site of visible contaminants. There was little evidence of redi stribution of bacteria to immediately adjacent but visually clean site s. However, the residual levels of both APCs and ECs directly at sites of faecal contamination after washing were still significantly higher than at visually clean sites. Application of HACCP principles to ovin e slaughter and dressing suggests that visible faecal material should be removed by trimming, whereas pre-evisceration washes can have a pra ctical and microbiologically validated role in the removal of wool. Th ere was generally a good correlation between APCs and ECs at the uncon taminated sites prior to pre-evisceration washing, suggesting that in some situations APCs can act as a useful indicator of both general car cass hygiene and the presence of faecal indicators.