Great hygienic effects from more strict requirements for the sheep slaughter
Report no: 2012: 16
Stricter requirements for the slaughter of sheep will provide great hygienic gains in most slaughterhouses in Norway, according to a risk assessment prepared by the Norwegian scientific committee for food safety (NSCFS) and commissioned by the Norwegian food safety authority (NFSA).
Methods used for the slaughter of sheep vary widely between abattoirs and industry's own slaughter hygiene principles are not as stringent for the slaughter of sheep as for other species.
On this background, the NFSA asked NSCFS to undertake an assessment of the possible hygiene benefits through reduced faecal contamination of carcasses using different slaughter techniques. NSCFS’s Panel for biological hazards has been responsible for undertaking risk assessment based on the available scientific literature.
Panel has selected four infectious agents to assess the possible effects from the stricter hygienic practices; E. coli, Campylobacter, Salmonella and Cryptosporidium.
The current practice of throat sticking and cutting of blood vessels, esophagus and trachea result in only limited effect of rodding. There will still be an effect of implementing rodding after the neck is skinned as the skinned surfaces are contaminated to a lesser extent, and contamination of the abdomen and chest cavity is avoided. There is also a 'Danish form of throat sticking" and the hygienic effect of rodding after this will probably be the same as for chest sticking.
If chest sticking is applied, the effect of rodding will be greater since it would allow rodding already at the first position after the bleeding and it will be possible to use the two-knives-method at skinning before rodding of the esophagus. By this method the contamination of wool, skinned surfaces, abdominal and chest cavity in addition to the operator's hands, equipment, walls and floor will be avoided.
With removal of the whole gastrointestinal tract: There is considerable hygienic gain from the use of plastic bags when ringing and retrieval of the intestines. If a plastic bag is not used and the rectum is inserted in the abdomen, the chances of contamination are larger.
With removal of the gastrointestinal tract after the colon was severed: There is a significant possibility of faecal contamination from the remaining bowel stump after the colon is severed, even if the operator is trying to "milk" contents away from the cut. Leakage from the bowel stump occurs very often, and there is significant possibility for contamination of the pelvic and abdominal cavity, slaughter surfaces, tools and hands.
The possibility of contamination can be reduced somewhat by closing the gut by a plastic clip with an appropriate dimension as near the cut as possible. There is also a significant possibility for contamination when the rectal stump is pulled out which can also be reduced to some extent if the rectum is equipped with a clip as mentioned above.
The hygienic effect of rodding and bagging will depend on the operator experience at these critical hygienic positions. Other positions and procedures, in addition to speed of slaughter line, play a significant role too.
Bacteriological analysis of carcasses to evaluate slaughter hygiene
Bacteriological analysis of carcasses according to Annex 852/2004 is mandatory and must be carried out weekly or, depending on the previous results once a fortnight. If the sampling locations are selected correctly and are analyzed separately, this form of bacteriological analysis of carcasses could reveal whether the practice of rodding and bagging are carried out according to GMP and GHP.