Pig welfare and carcase quality: a comparison of the influence of slaughter handling systems at two abattoirs

Hand-held lactate analyzer as a tool for the real-time measurement of physical fatigue before slaughter and pork quality prediction

The objectives of this study were to assess the relationship between blood lactate variation measured at the plant, and pork quality variation on a large sample size and under commercial preslaughter handling conditions. A total of 600 pigs were randomly chosen on arrival at a commercial slaughter plant and blood samples taken from the ear vein at unloading (UN), after lairage (LA), in the restrainer (RE; before stunning) and at exsanguination (EX) were analysed for lactate content using a Lactate Scout Analyzer (LSA). In order to have a large range of measures, pigs were distributed into two groups; one kept in lairage overnight (G1) and the other for 2 to 3 h (G2) before slaughter. Meat quality was assessed in the Longissimus thoracis (LT), Semimembranosus (SM) and Adductor (AD) muscles by measuring the pH 30 min postmortem (pH1) and at 24 h postmortem (pHu), the colour and the drip loss. Blood lactate levels did not differ between G1 and G2 (P>0.05). A reduced muscle lactate and glucose contents (P=0.02 and P=0.004, respectively) resulting in a lower (P<0.001) glycolytic potential (GP) was observed in the LT muscle of G1 pigs when compared with G2 loins. In the LT muscle of G1 pigs, the lower GP resulted in an increased pHu (r=-0.67; P<0.001), decreased drip loss (r=0.57; P<0.001) and darker colour (r=0.50; P<0.001) compared with G2. In both G1 and G2 pigs, the lower GP was correlated to higher pHu value in the SM and AD muscles (r=-0.73; P<0.001). The greatest correlation was observed in G2 between blood lactate levels at LA and pHu value of the SM and AD muscles (r=0.46 and r=0.44, respectively; P<0.001 for both muscles). The second greatest correlation was found between blood lactate levels at EX and pH1 value in the SM muscle in both groups (r=-0.37 and r=-0.41, respectively; P<0.001 for both groups). Based on the results of this study, it appears that blood lactate levels, as measured by the LSA, reliably reflect the physiological response of pigs to perimortem stress and may help explain the variation in pork quality.

Effects of preslaughter handling on the behaviour, blood biochemistry and carcases of farmed red deer

Eight groups of six red deer (four groups of males and four groups of females) were held overnight in an unfamiliar paddock, after which they were moved into a holding pen and slaughtered sequentially by stunning with a captive bolt pistol in a restraining pen. On entering the restraining pen, half the deer in each group were stunned immediately, but the other half were stunned after 10 minutes. Deer spent much of the initial period in the holding pen standing stationary in 'alert' postures, but became less alert over time. A significantly higher proportion of males than females were observed in alert 'head-up' postures in the restraining pen. Deer held in the restraining pen for 10 minutes had significantly higher plasma cortisol concentrations than those which were stunned immediately. Females had a significantly higher glycogen concentration postmortem in both the liver and semimembranosus muscle than males, and deer held in the restraining pen for 10 minutes had a significantly lower liver glycogen concentration than deer which were slaughtered immediately. Males had significantly higher semimembranosus muscle pHu values than females, although the differences were small, and of the 14 deer with pHu values above 6-0, 11 were males.