Effect of mixing boars during lairage and pre-slaughter handling on pork quality

Abstract

Forty-eight crossbred (Large White × Landrace) boars were used in a 2 × 2 factorial design to determine the effects of mixing unfamiliar pigs during lairage and the use of electric goads just prior to slaughter on muscle glycogenolysis and subsequent pork quality. The treatments included 2 mixing treatments (familiar pigs kept together during lairage and unfamiliar pigs mixed during lairage) and 2 handling treatments [minimal handling and negative (electric goad) handling pre-slaughter]. Pigs mixed during lairage had lower muscle glycogen and lactic acid at 5 min, 40 min, and 24 h post-slaughter than familiar pigs kept together during lairage. Mixing of unfamiliar boars also resulted in higher ultimate muscle pH, a higher incidence of dark, firm, dry (DFD) pork, and a lower incidence of pale, soft, exudative (PSE) pork compared with familiar pigs kept together during lairage. The use of an electric goad prior to slaughter did not affect muscle glycogen in mixed pigs, but in unmixed pigs there were large numerical diffferences in glycogen concentrations. The negatively handled unmixed pigs had a trend for lower glycogen concentrations which did not reach significance. This was probably due to the small sample size. However, pigs negatively handled pre-slaughter had higher lactic acid concentration at 5 min post-slaughter compared with minimally handled pigs. This experiment has demonstrated that mixing of unfamiliar boars can have a major impact on pork quality, resulting in a high incidence of DFD pork and a reduced incidence of PSE.