Effects of Dark Brooders on Behavior and Fearfulness in Layers

Abstract

Simple SummaryChicks require heat to maintain body temperature during the first weeks after hatch. Heat is normally provided by use of heating lamps or whole-house heating, but an alternative is dark brooders, i.e. horizontal heating elements equipped with curtains. The effects of providing layer chicks with dark brooders during the brooding period on behavior and fearfulness were investigated. Brooders resulted in chicks showing less locomotive activity, feather pecking and fleeing. Also, a long-term reduction of fearfulness in brooder birds was found. Results support the suggestion that rearing with dark brooders can be a successful method of reducing or preventing some of the major welfare problems in layers.AbstractChicks require heat to maintain body temperature during the first weeks after hatch. This may be provided by dark brooders; i.e., horizontal heating elements equipped with curtains. The objective was to test effects of rearing layer chicks with dark brooders on time budget and fearfulness. Behavioral observations were performed during the first six weeks of age. Three different fear tests were conducted when the birds were age 3–6, 14–15 and 26–28 weeks. During the first four days, brooder chicks rested more than control chicks whereas they spent less time drinking, feather pecking and on locomotion (p ≤ 0.009). On days 16, 23, 30 and 42, brooder chicks spent less time on feather pecking, locomotion and fleeing (p ≤ 0.01) whereas foraging and dust bathing occurred more often on day 42 (p ≤ 0.032). Brooder birds had shorter durations of tonic immobility at all ages (p = 0.0032), moved closer to the novel object at age 15 weeks (p < 0.0001), and had shorter latencies to initiate locomotion in the open-field test at age 28 weeks (p < 0.0001). Results support the suggestion that dark brooders can be a successful method of reducing or preventing fear and feather pecking in layers.

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

“…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).…”

“…First, heating a large space costly in terms of economics and environmental impact. Second, in conventionally heated barns, chicks are not provided with shelter, dark areas, or resting spaces, aspects normally provided by a broody hen which may be important to their development (4)(5)(6)(7).…”

“…Chicks bred with broody hens are less fearful than chicks bred without mother hens (8). Likewise, brooders have been shown to reduce the level of fear in chicks (7). 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).…”

“…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).…”

Analysis of the brain transcriptome in lines of laying hens divergently selected for feather pecking

“…With the aim to gain further insight into the underlying mechanisms, we used RNAsequencing (RNA-seq) to analyze the whole brain transcriptomes of 24 full-sib pairs of hens from two layer lines divergently selected for FP behavior. As light intensity is known to trigger the actual behavior given the respective motivation [27,28], we not only compared transcriptomes between lines but also before and after light stimulation. To our knowledge, this is the first comprehensive brain transcriptome study using RNAseq with respect to feather pecking in layers.…”