Effects of different types of dark brooders on injurious pecking damage and production-related traits at rear and lay in layers

Injurious pecking (IP) remains one of the major welfare challenges in housing of laying hens worldwide due to the negative consequences it inflicts on animal welfare and economy. One potential solution to reduce IP is the use of dark brooders as the primary heat source during rearing. The objective was to investigate effects of rearing layer chicks with different management strategies and size allowances of dark brooders on IP and production-related traits during rear and lay. Groups of 100 to 103 Isa Warren chicks were reared either with one of 4 brooder types (n = 4 per treatment) or with whole-house heating (control: n = 6). Brooders were either large (54 cm²/chick) or small (72 cm²/chick) and kept at a fixed height or periodically lifted. Plumage and skin condition were scored at age 6, 16, and 28 weeks. The birds were weighed at age one, 16, and 28 weeks. Data on egg production and mortality were registered daily from wk 16 until 27 wk of age. Minor differences between brooder treatments were found but with no clear trend pointing to a specific brooder treatment being superior. In contrast, major differences in IP damage were found between birds reared with or without brooders. Brooder birds had a better plumage condition throughout the experiment (P < 0.001) and fewer wounds during lay (P < 0.001). Mortality due to cannibalism in the brooder treatments tended to be lower during rear (P = 0.066) and was lower during lay (P < 0.001). There was no treatment effect on body weight on d 7 (P = 0.48). Brooder birds laid fewer floor eggs (P < 0.001) and had higher total egg production (P < 0.001). We conclude that an automatic system lifting the brooders regularly may be skipped, and a size allowance of 54 cm² per chick is sufficient, leaving the design of brooders simple and cheap. Rearing layer chicks with dark brooders can be a successful method of reducing prevalence of IP and floor eggs, whereby mortality is reduced, leading to improved welfare, egg quality, and production performance.