The effect of stress, applied immediately before stunning, on pork quality.

The effect on meat quality characteristics of stress, applied during a short period just before stunning, was studied on slaughterpigs (113 boars, 85 gilts). Sexes were kept separately and only pigs that had been stunned correctly were included. Aggressive behaviour during lairage occurred more frequently in boars (about twice) than in gilts. Just before stunning, two animals of the same sex, that were lairaged for an equal period at the slaughter facility, were moved as quietly as possible to the stunning pen, after which one pig was stunned immediately and the other subsequently forced to move through the stunning pen over a period of 1 min. Stress resulted in lower pH values and higher temperatures in the semimembranosus (SM) and the longissimus lumborum (LL) muscles and a higher rigor mortis value of the SM, at 45 min post mortem. Stress affected water holding capacity of the LL negatively at 24 h p.m. Statistically significant interactions were present for sex×stress for several meat quality traits. In general, gilts reacted more strongly to short periods of stress than did boars.