Regrouping in lactating goats increases aggression and decreases milk production

With the aim of testing the hypothesis that regrouping decreases milk production in French Alpine goats that were lactating, a study was done using two groups (n = 8, 7). During their third month after parturition, four goats from each group were exchanged (first regrouping) between pens and left for 2 weeks, then the same two subgroups of four goats were taken back to their original pen for another 2 weeks (second regrouping). In the third regrouping, the two groups were all placed in the one pen. Milk production and social behaviour were measured daily before and after each regrouping. All regroupings led to an increase in aggressive behaviours that last by 1–2 days. Mean daily milk production decreased after first (2.82 ± 0.2 kg versus 2.53 ± 0.2 kg; P < 0.05) but not after second and third regrouping. It is concluded that aggressive behaviour increases after all regroupings, whereas milk production decreases only after the first regrouping, suggesting an important capacity of adaptation to a novel and stressful managements in the French Alpine goat. The study highlights the importance of considering effects of common practices in herd managements on social behaviour and production.