Relationships among pre-slaughter stress, rigor mortis, blood lactate, and meat and carcass quality in pigs

The aim of this study was to examine the relationships among pre-slaughter stress, rigor mortis, blood lactate, and meat and carcass quality in 100 pigs (cross between Naima sows and hybrids P-76 PenArLan boars). Before slaughter lairage time, handling and pig behavior were assessed for each animal. At exsanguination blood concentrations of lactate and cortisol were determined, while post-mortem were assessed: initial and ultimate pH value, temperature, drip, sensory and instrumental colour and marbling. On the carcasses the degree of rigor mortis and skin damage score were estimated, as well as carcass quality parameters. More developed (p<0.01) rigor mortis was observed after long lairage compared to short lairage. Higher intensity of rigor was found in pigs with higher blood lactate level (p<0.05) and with a greater thickness of subcutaneous fat tissue (p<0.05) and lower lean meat content (p<0.01). Higher blood lactate level was observed after long lairage compared to short (p<0.05) and after rough handling compared to gentle handling (p<0.01). In the group with blood lactate from 10 to 15 mmol/l meat temperature and skin blemishes score increased, while in the group with the highest blood lactate concentration (>15 mmol/l) initial pH decreased and L* value increased. These results suggest that in groups with higher blood lactate concentrations meat quality deteriorates.