van den Oever, A. C. M., Rodenburg, T. B., Bolhuis, J. E. et al. 2020. Relative preference for wooden nests affects nesting behaviour of broiler breeders. Applied Animal Behaviour Science 222, 104883.

Optimising nest design for broiler breeders has benefits for both the animals and the producers. The welfare of the hens will increase by providing preferred housing, while also reducing eggs laid outside the nests. These floor eggs cause economic losses by compromised automatic egg collection and reduced saleability and hatchability. Attractiveness of nests can involve factors such as seclusion, material and microclimate. In this study, four nest box designs were offered in a relative preference test: a plastic control nest, a plastic nest with a partition to divide the nest in two areas, a plastic nest with a ventilator underneath to create air flow inside the nest and a wooden nest. Six groups of 100 hens and 9 roosters had access to these four nests in a randomised location during the ages of 20 to 34 weeks. Nest and floor eggs were collected five days a week. Camera images from inside the nests made during the ages of 24–25 weeks and 26–27 weeks were analysed for behaviour. This included general activity, nest inspections, nest visits and social interactions. At 32 weeks of age the wooden nests were closed, and the subsequent response of the hens was monitored in terms of number of eggs. We found a clear preference in number of eggs for the wooden nest (69.3 ± 1.0%) compared to the control nest (15.1 ± 0.8%), partition nest (10.2 ± 0.5%) and the ventilator nest (5.4 ± 0.4%; p<0.0001 for difference between all nest designs). The preference for the wooden nest was also reflected in an increased time spent sitting, together with fewer nest inspections and visits per egg laid in the wooden nest. The preference for the wooden nest led to crowding, which caused an increased amount of piling, nest displacement, aggression and head shaking. The fact that the hens were willing to accept the crowded circumstances in these nests, underlines the strength of this preference. After the wooden nests were closed, the hens chose a new nest based on a combination of nest design and location. The control nest was still preferred over the other two plastic designs, although the neighbouring nests were overall preferred to the non-neighbouring nests. This study shows how the material used for nests is an important factor in suitability and should therefore be taken into account when designing nests.