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

Abstract

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.

Effects of Dark Brooder Rearing and Age on Hypothalamic Vasotocin and Feather Corticosterone Levels in Laying Hens

“…Given the impracticality of housing broody hens with chicks in industrial situations on the one hand, and the desirability of introducing aspects of maternal care to improve welfare and reduce energy use on the other hand, investigation of the effects of the use of dark brooders during rearing on physiological parameters related to stress and welfare is of strong interest. Previously published results from the present group of animals demonstrated strong positive effects of dark brooders on plumage condition, wound reduction and reduction in mortality rates (13). To further examine mechanisms behind these changes, we therefore investigated effects of rearing hens with a dark brooder from hatch through 6 weeks of age on CORT concentrations in feathers and on AVT expression in the hypothalamus at 16 and at 28 weeks of age.…”

“…382 (10 June 1987) and Acts 333 (19 May 1990), 726 (9 September 1993) and 1016 (12 December 2001). This study is part of a larger project that also evaluated the effects of brooders on welfare, including behavior, fear, injurious pecking damage, mortality and production parameters (7,13).…”

“…Osmotic stress also increases c-fos expression in AVT-positive neurons in the SO in chicken, zebrafinch, ring dove, and Japanese quail (43), and increases neuron size in the SO in quail (44,45). It is interesting in this context that animals reared with brooders spent less time drinking during the first 4 days of life, probably due to a more efficient thermoregulation resulting in less respiratory evaporation (13).…”

“…When 16 weeks old the group sizes were reduced to 50 birds/group. There were four different brooder treatments (each consisting of four replicate groups) differing in size of the available area under the brooder per chick (54 or 72 cm 2 ) and in whether the brooder was raised at regular intervals [for more details see (13)]. Due to the time consuming and costly nature of the procedures applied in the present study, only one of the brooder treatment, i.e., four treatment groups, and only five of the six control groups were included.…”

“…Fear is a strong stressor that inhibits the immune system, growth, feed exploitation, and egg production (9), and may also induce or exacerbate feather pecking in laying hens (10). There is strong evidence that the use of dark brooders reduces feather pecking not only during rearing, but as a long-lasting effect into the laying period (6,7,(11)(12)(13).…”