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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