PSV-2 A simple study of the social rank and perch competition of laying hens housed in small furnished cages

Abstract

Abstract Social animals form social hierarchies to maintain the relative stability of the population. Individuals with high social rank can, to some extent, limit the priority of individuals with lower social status to obtain resources, such as food, habitat and spouse. The perch behavior is the instinctive behavior of laying hens. Hens have the motivation to choose perch habitat. Therefore, perch is an effective competitive resource for laying hens. The objective of this study was to examine the social order of small groups of the laying hens housed in furnished cages and to determine the dominant and subordinate hens how to use the limited perch resources. A total of 108 Hy-line Brown rearing hens at 8 weeks of age were randomly divided into three treatment groups, namely, 1) perch increasing group by adding 15cm each time from 0 to 90 cm length (PI group), 2) perch decreasing group by cutting 15cm each time from 90 to 0 cm length (PD group) and 3) perch constant with 90 cm (PC group). There were 6 replicates in each treatment group, 6 birds in each replicate, and the stocking density was 833/cm2. The utilization of limited resources in laying hens was judged by three parameters, i.e. the number of individual occupancies, total use time and single use time. Data were analyzed by using repeated measure analysis of variance (ANOVA). The results showed that the number of occupancies and the total use time of perch by the dominant hens were significantly higher than the subordinate ones (P < 0.01) in PI, PD and PC groups. The number of individual perch occupancy was positively correlated with the social rank of the hens. This study confirmed that the dominant hens occupied the perch for longer time than the subordinate individuals.