Nesting behaviour of broiler breeders

Broilers have been selected for growth related characteristics, which are negatively correlated to reproductive traits. This genetic background creates challenges in broiler breeders, as the hens do not make optimal use of the nests provided leading to dirty and cracked eggs. Despite the economic importance of this problem, little research has been done on nesting behaviour in broiler breeders. This project aims to investigate which factors are involved in nest site selection of broiler breeder hens and to create practical improvements in housing design. The first experiment focuses on nest design preferences, where three alternatives to a standard nest will be offered to groups of hens. This preference will then be related to the personality traits sociability and fearfulness, measured with density related permanence and tonic immobility tests. The second experiment will compare two genetic strains on leg health and social interactions. The effect of introducing perches at an age of 20 weeks on leg health, measured by scoring for footpad dermatitis and gait, will be investigated. Leg health will furthermore be related to mobility, fertilisation and production. Social interactions amongst females and between females and males are expected to influence nest site selection as well. Dominant females might attract submissive females to certain nests, but can also prohibit submissive females access to the nests. Feral males are known to escort females to suitable nest sites, although it is unknown whether this holds true for domestic chickens. By scoring social interactions and nest site, these possible relations can be studied. A final field experiment will be conducted at a commercial farm, fitted with nests designed according to the preferences of the first experiment and with or without perches as proven optimal according to the second experiment. Productivity, fertilisation, leg health and behaviour will be recorded to measure the performance of this improved system.