Effect of distance moved during loading, lairage time, and distance moved to stun on blood lactate concentration of pigs in a commercial slaughter plant

L. N. Edwards1, T. Grandin1, T. E. Engel1, M. J. Ritter2, A. Sosnicki3, B.A. Carlson1, and D. B. Anderson1
1Colorado Slate University, Fort Collins
2Elanco Animal Health, Greenfield, IN
3PIC, Hendersonville, TN

Journal of Animal Science 87: (E-Suppl. 2/J) p.564.

Two studies were conducted to assess the relationship between management and blood lactate concentration (LAC) of pigs. A 2 x 2 x 2 repeated measures factorial design was used (Exp. 1, n = 64; Exp. 2, n = 144: pig = experimental unit) exploring distance moved at the farm (T1), lairage time (T2) and distance moved to stun (T3) on LAC of pigs in a commercial slaughter plant. Pigs were moved a short (15 m) or a long (46 m) distance (T1) during loading at the farm. Pigs were transported for approximately 2.5 h to the packing facility where they were rested for a short (30 min) or long (4.5 h) period (T2). After lairage, the pigs were moved a short (20 m) or long (300 m) distance to stun (T3). Pigs from each treatment subclass were equally distributed on each truckload. Pigs were electrically stunned and exsanguinated. A lactate analyzer was used to measure LAC at seven time points during the marketing process: baseline, post-load, pre-unload, post-unload, post-lairage, post-movement to the stunner and at exsanguination. In Exp. 1 and 2 LAC changed (P< 0.0001) during the marketing process, the highest LAC was observed at loading and exsanguination. Long distance moved during loading resulted in higher (8.3 & 6.0 mM; P = 0.0001) LAC during loading (Exp. 2). Unexpectedly, in Exp. 2, pigs rested for a longer period had higher LAC post-lairage (3.6 & 3.0 mM; P = 0.02), post-movement to stun (4.7 & 3.8 mM; P = 0.01) and at exsanguination (8.1 & 5.5 mM; P = 0.0001). In Exp. 1, pigs rested for a long period had greater increases (change between time points) in LAC during the immediate pre-stun handling ( 5.6 & 3.6 mM; P = 0.003). Differences between experiments could be explained by difference in season, facility design and specifics of experimental protocols. Blood lactate was greater in pigs moving a short distance to stun (7.6 & 5.8 mM, Exp. 1, 7.2 & 6.0 mM, Exp. 2; P < 0.04) than those moving the long distance. This study emphasized the impact that pre-slaughter management has on LAC of pigs from farm to stun and demonstrates that the greatest handling stress is at loading and exsanguination.

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