The physiological responses to fighting in pigs and the consequences for meat quality

Eighty commercial hybrid pigs (55 kg) consisting of equal numbers of boars and castrates were slaughtered after a 24 h fast, having been transported 48 km to the abattoir and laired for 1 h. During transport and lairage, pigs from different rearing pens were mixed and some fought. Photographs of each carcass were scored for the degree of fighting damage. The greater the damage the higher were the concentrations of cortisol (P<0.001), glucose (P<0.01) and lactate (P<0.001) in blood collected from the pigs at slaughter. The amount of ascorbic acid was lower (P<0.05) in the adrenal glands from pigs which showed most evidence of fighting. The pH45 in the m.longissimus dorsi, its colour and the loss of drip during storage were not significantly related to the amount of fighting but the pHu in both the m.semimembranosus and m.adductor was higher (P<0.05) in the carcasses showing greatest damage. There was a tendency for boars to show more carcass damage but there were no significant differences between the sexes in the measures of meat quality.