Simulated loading and unloading of pigs of two slaughter weights: effects of the group size on their ease of handling and physiological response

This is the authors' abstract. We don't add key points for this paper.

This study aimed to evaluate the effects of handling barrows of two slaughter weights, light (L: 135.1 kg average final weight) and heavy (H: 152.9 kg average final weight), and group sizes (3 vs. 6 pigs/group) through a simulated loading and unloading procedure on their behavioural and physiological response. Behaviour was observed in 120 pigs, while heart rate (HR) and whole blood lactate concentrations were evaluated in a subsample of 81 pigs (3 pigs/group). The interaction body weight × group size had no effect on handler interventions, pig behaviours, and post-handling blood lactate concentration. Handling time was longer in H pigs ( P = 0.05), but the number of handler interventions and paddle noise was greater only in larger groups of pigs ( P ≤ 0.05), resulting from their higher frequency of turning back, backing-up, and going backward ( P = 0.04, P = 0.02, and P = 0.04, respectively). Pigs handled in larger groups presented greater post-handling blood lactate concentrations ( P < 0.01). In L pigs, the HR increased more when handled in smaller than larger groups ( P = 0.03) without significant consequences during the recovery period. Our results suggest that a smaller group size would reduce pigs’ fatigue and ease their handling.