Effects of Body Weight Groupings on Productivity, Feather Loss, and Nervousness of Caged Hens

Abstract

Two experiments compared performance traits, feather loss, and nervousness of hens kept in contrasting homogeneous and heterogeneous body weight groupings. In addition, 15-day periods of daily uterine palpating vs nonpalpating for an egg in the uterus were compared for effects on egg production. Eighteen-wk-old pullets were weighed and characterized as light, medium, or heavy and housed in laying cages at 19 wk for a 50-wk production period. In Experiment 1, two hens were placed in each cage and there were three treatment groups: both light (L), mixed or 1 heavy and 1 light (X), and both heavy (H). In Experiment 2, three pullets were used per cage; a medium-weight group (M) was included and mixed cages included 1 heavy, 1 medium, and 1 light weight bird. In an ancillary experiment, 50-wk-old hens were also palpated or not palpated for an egg in the uterus over a single 15-day period.Results indicated that differences that were present in initial body weight groups persisted over the 50-wk period in Experiments 1 and 2 with no effect of weight grouping on body weight gain, egg production, and livability. Differences that were associated with weight groups were: age at sexual maturity, egg weight, egg mass, and nervousness score. No differences in mean feather scores were present among weight groups.Comparisons between individual hens of the same relative weight but kept in homogeneous or heterogeneous weight groups failed to indicate competitive advantages or disadvantages in egg production, feathering, and nervousness scores. No significant associations were found between nervousness scores of individual hens and other traits except for total body weight gain in Experiment 1, in which individuals that gained more were less nervous in the X groups (r = −.55).Palpating hens daily for two 15-day periods significantly increased hen-day egg production in Experiment 2 and nonsignificantly in Experiment 1, with no influence of palpation on hen-day egg production, egg weight, or egg mass in the ancillary experiment.