THE EFFECT OF PRESLAUGHTER FEED RESTRICTION AND GENOTYPE FOR STRESS SUSCEPTIBILITY ON PORK LEAN QUALITY AND COMPOSITION

Abstract

The effect of the duration of feed restriction prior to slaughter on the ultimate lean meat quality of the longissimus dorsi muscle (loin-eye) was tested in three lines of pigs of differing genotypes with respect to stress susceptibility. Pigs of the Lacombe breed (genotype NN), none of which has been shown to be halothane-positive, yielded a low incidence (0–4%) of pale or soft, exudative pork for all three feed restriction treatments (0,24 and 48 h off feed). The meat quality of pigs from the halothane-positive line (genotype nn) was altered dramatically by the off-feed treatment. The incidence of pale-colored pork decreased from 57% at 0 h off feed to 9% at 48 h off feed, and the incidence of soft, exudative pork decreased from 87% at 0 h off feed to 48% at 48 h off feed. NN × nn crossbred pigs (genotype Nn), all of which gave a negative response to the halothane test, were intermediate in quality between the other two genotypes at all times off feed. In no instance did the feed restriction treatment produce dark, firm, dry (DFD) meat. These data suggest, first, that halothane-negative carriers of the halothane gene may contribute considerably to the incidence of pale, soft, exudative (PSE) pork, and secondly, the manipulation of the length of time of feed prior to shipping for slaughter may offer potential as a management practice to improve meat quality. Key words: Feed restriction, fasting, stress susceptible, quality