Grouping piglets by sex at weaning reduces aggressive behaviou

The aim of this work is to reduce aggressive behaviour when piglets are grouped at weaning.The experiment is conducted to determine whether it is better to group piglets by sex at weaning or to mix them in malefemale groups. 192 Large White piglets were weaned at 28 days and assigned to 4 conditions, with 6 groups of animals/ condition : (Fam-MF) 4 male and 4 female reared together from birth, (Etr-M) 8 unfamiliar male piglets, (Etr-F) 8 unfamiliar female piglets, and (Etr-MF) 4 male and 4 female unfamiliar piglets. All groups were videotaped at 28, 29, 31, 39 and 46 days for 2h. Aggressive interactions were quantified. Scratches on each piglet were counted on day 27, 29 and 33. Feeding consumption and piglets’ weights were quantified from birth to 63 days. On J28 and J29, fighting duration is longer in Etr-MF than in Fam-MF and Etr-F (p