Effect of Pre-Slaughter Feed Restriction on Pig Carcass Yield and Pork Quality

A.C. Murray, W. Robertson, F.M. Nattress and A. Fortin

Agriculture & Agri-Food Canada Research Centre, 6000 C & E Trail, Lacombe, AB T4L 1W1

Meat packers prefer that pigs be held off feed overnight prior to slaughter, because this treatment results in somewhat lower frequency of PSE pork and, by reducing gut fill, reduces carcass microbial contamination. On the other hand, withdrawal of feed may cause a lower carcass yield and therefore less profit for producers. What is the optimal time off feed (TOF) prior to slaughter?

In an attempt to address this question, pigs were treated according to one of three possible scenarios prior to slaughter. Each included a 2 h transportation from the swine barn to the abattoir.

Treatment	TOF at Piggery (h)	TOF at Abattoir (h)	Total TOF (h) at Slaughter Times
			9:30	11:30	1:30 PM
1	0	0, 2, 4	3	5	7
2	0	15, 17, 19	18	20	22
3	15	0, 2, 4	18	20	22

Live weight yields for the three slaughter times averaged 94.2 and 93.5% for treatments 2 and 3, respectively. For treatment 1, these yields decreased from 96.8 to 95.5% as TOF increased from 3 to 7 h. Losses were from both carcass and non-carcass components (gastrointestinal tract). Commercial hot carcass yields were 79.5, 80.4 and 80.9% of live-slaughter weight and 76.5, 75.7 and 75.6% of treatment starting weight, respectively, for treatments 1, 2 and 3, with no differences between slaughter times. Carcass cooler shrink, yield of wholesale cuts (based on cold side) and lean yield in wholesale cuts, as well as grading probe fat thickness, lean depth and lean yield were not affected by treatment.

The lean muscle quality traits, pH, drip loss and tenderness, showed no treatment effects, whereas color meter measurements indicated that extended TOF slightly darkened the meat.

Implication: The removal of feed from pigs for 18-22 h prior to slaughter results in a decrease in commercial hot carcass yield of 0.8-0.9% of pre-treatment weight with no adverse effects on lean muscle quality. This should be considered in the negotiation of an equitable settlement between producers and packers.