Association of plasma stress markers at slaughter with carcass or meat quality in pigs.

Summary: The association between plasma level of three stress markers at slaughter (cortisol, neopterin, Hsp70) and carcass and meat quality traits was studied in pigs. The study comprised data from 51 pigs fattened on the same farm (one crossbreed, no RYR1 mutation) and slaughtered in one abattoir in five batches. At slaughter blood was collected for the analysis of neopterin, cortisol and HSP70 level using commercial enzyme immunoassay kits. A day after the slaughter, carcass traits (fat and muscle thickness, lean meat percentage, longissimus dorsi (LD) muscle and fat area, belly leanness and ham weight) and meat quality traits (pH 1 at 1 h, pH U at 24 h post-mortem, Minolta L*a*b* and drip loss) were assessed. No significant differences between slaughter batches were observed for stress markers and meat quality. However, individual animal variation of stress markers within slaughter batch was very high. Correlation analysis demonstrated no association between plasma neopterin and Hsp70 levels with any of carcass or meat quality properties. On the contrary, significant correlations of cortisol level were observed with some carcass or meat quality properties. Higher cortisol levels were associated with thicker subcutaneous fat (r=0.30 to 0.33) and lower carcass meat percentage (r=–0.37 to 0.41), which indicates that higher cortisol levels on the long term basis increase body fatness. Regarding meat quality, higher cortisol levels were associated with higher pH 1 (r=0.36 to 0.58) and pH U (r=0.36 to 0.32), and consequently with lower LD Minolta L* (r=–0.44), b* (r=–0.38) and drip loss after 24 (r=–0.44) and 48 hours (r=–0.39) suggesting that cortisol level at slaughter reflects more than just acute preslaughter stress.