Feather colour affects the aggressive behaviour of chickens with the same genotype on the dominant white (I) locus.

Changsheng Nie,Liping Ban,Lujiang Qu,Zhonghua Ning,Arda Yildirim

doi:10.1371/journal.pone.0215921

Abstract

Aggression in chickens is a serious economic and animal welfare issue in poultry farming. Pigmentation traits have been documented to be associated with animal behaviour. Chicken pecking behaviour has been found to be related to feather colour, with premelanosome protein 17 (PMEL17) being one of the candidate genes. In the present study, we performed a genotypic and phenotypic association analysis between chicken plumage colour (red and white) and aggressive behaviour in an F1 hybrid group generated by crossing the autosomal dominant white-feathered breed White Leghorn (WL) and the red-feathered breed Rhode Island Red (RIR). In genetic theory, all the progeny should have white feathers because WL is homozygous autosomal dominant for white feathers. However, we found a few red-feathered female chickens. We compared the aggressiveness between the red and white females to determine whether the feather colour alone affected the behaviour, given that the genetic background should be the same except for feather colour. The aggressiveness was recorded 5 days after sexual maturity at 26 weeks. Generally, white plumage hens showed significantly higher aggressiveness compared to the red ones in chasing, attacking, pecking, and threatening behaviour traits. We assessed three candidate feather colour genes—PMEL17, solute carrier family 45 member 2 (SLC45A2), and SRY-box 10 (SOX10)—to determine the genetic basis for the red and white feather colour in our hybrid population; there was no association between the three loci and feather colour. The distinct behavioural findings observed herein provide clues to the mechanisms underlying the association between phenotype and behaviour in chickens. We suggest that mixing red and white chickens together might reduce the occurrence of aggressive behaviours.

Highlights

Aggressive behaviour in chickens is a widespread economic and animal welfare issue in poultry farming, and many factors such as food, mates, and social rank affect its occurrence [1, 2]
Hens with two feather colours obtained from the cross were raised in the same facility under the same environmental conditions
Body weight differed (G1 and G2 were significantly heavier than G3 and G5) in six groups at the age of 20 weeks (Table 2), no significant difference in body weight was found in the repeat groups (G1 vs. G2, G3 vs. G4, and G5 vs. G6)

Summary

Introduction

Aggressive behaviour in chickens is a widespread economic and animal welfare issue in poultry farming, and many factors such as food, mates, and social rank affect its occurrence [1, 2]. As a complex trait in chicken, aggressiveness has been found to be present, albeit with low heritability (h2 = 0.04–0.17) in various studies [4,5,6,7,8], and aggressive pecking has been reported to be affected by a variety of environmental factors, including light intensity [9], stocking density [10, 11], food [12], feeding methods [13], group size [14], and male presence [1]. The PMEL17 locus could affect explorative and social behaviours in chickens [17]

Methods

Results

Discussion

Conclusion