The effect of perches and aviary tiers on the mating behaviour of two hybrids of broiler breeders

Abstract

Broiler breeders are kept for the production of fertile eggs. They face serious welfare problems like aggressive behaviour of the males towards females during mating. Furthermore, broiler breeders are usually kept without perches which are a highly valued resource in chickens. The aim of the study was to investigate how the provision of aerial perches and perches on aviary tiers influenced the mating behaviour in a fast growing (Ross 308) and a more slowly growing (Sasso) hybrid. Control pens (C) were equipped with a litter area, raised slats leading to nestboxes, male and female feeders and a drinking line. Pens with perches had 8 aerial perches arranged in a reverse ‘V’ on the slats (P). Pens with aviaries contained a low 4-tier aviary with wooden perches (A) on the slats. We employed a full factorial design with the factors hybrid and treatment (C, P, A) with 3 replicates. Mating behaviour was analysed from 24 h video recordings at 35 and 40 weeks of age (WOA). Data were analysed with generalized linear models corrected for over dispersion. The experimental unit was the pen nested in treatment and hybrid. The number of matings was not affected by the treatment but the location of matings differed between treatments (F2,13 = 6.37, P = 0.01) and hybrids (F1,13 = 12.45, P = 0.004). Ross 308 mainly mated on the litter and Sasso on the slats but Sasso in A mainly mated on the litter. Crouching by the hen and thus waiting for the male to mount was shown more in A than C and more in P than in C (t13 = 2.2, P = 0.047; t13 = 2.18, P = 0.048) and was more frequent in the Ross than in the Sasso hybrid (F1,99 = 11.57, P = 0.001). Likewise, Ross 308 hens struggled less than Sasso hens during mating (F1,98 = 5.93, P = 0.02). Sasso hens appeared to actively avoid the areas where males were present, possibly caused by the sexual size dimorphism which was much greater in the Sasso than in the Ross 308 hybrid. In conclusion, aviaries and perches did not reduce mating behaviour. On the contrary, aviaries favoured acceptance of copulations in the female.