Feather pecking behavior in laying hens: Hypothalamic gene expression in birds performing and receiving pecks

Abstract

Feather pecking (FP) is a welfare and economic problem in the egg production sector. Beak trimming, the current method used to reduce FP, is also criticized. The present study used gene expression to explore the biological mechanisms underlying this behavior, which could lead to a greater understanding of the cause and a tool to mitigate the problem. White Leghorn hens performing and receiving FP, as well as neutral control birds, were identified on a commercial farm. Hypothalamic RNA from 11 peckers, 10 victims, and 10 controls was hybridized onto GeneChip Chicken Genome Arrays (Affymetrix Inc., Santa Clara, CA) to compare gene expression profiles in the different groups. Eleven transcripts corresponding to 10 genes differed significantly between the 3 groups (adjusted P < 0.05). Eight of these transcripts differed in the peckers compared with the controls, 1 was upregulated in the victims compared with the controls, and 6 differed significantly in the peckers compared with the victims. Additionally, 5 transcripts showed a trend (adjusted P < 0.1) to differ in the pecker-victim comparison. Some of the products of the differently expressed genes are involved in disorders, such as intestinal inflammation and insulin resistance, which fit well with the previously proposed hypothesis that FP is an abnormal foraging behavior. Other findings may also support the proposal that FP is linked to immune mechanisms and may serve as an animal model for obsessive compulsive disorder in humans. In conclusion, this study provides a gene list that may be useful in further research on the mechanisms behind FP.

The presence of extreme feather peckers in groups of laying hens

“…Chickens from an HFP line were found to have significantly higher locomotor activity compared with chickens from an LFP (Kjaer, 2009;Lutz et al, 2016). Other behaviors, such as those involved in aggression (Bessei et al, 2013;Bennewitz et al, 2014), exploration (de Haas et al, 2010Brunberg et al, 2011) and fear Boegelein et al, 2014, Grams et al, 2015b have been reported to be associated with feather pecking and may have a complementary effect on this behavior.…”

Relationships between range access as monitored by radio frequency identification technology, fearfulness, and plumage damage in free-range laying hens

“…Fearfulness in chickens is influenced by multiple factors such as previous experience, housing conditions, interaction with humans, and genetic differences (Jones and Faure, 1981;Rodenburg et al, 2013). Individual variation is an important factor to consider in behavioural studies (Brunberg et al, 2011;Rodenburg et al, 2013;Bessei and Kjaer, 2015), and fearfulness is thought to vary on an individual bird level due to differences in brain morphology and serotonin turnover (Gruss and Braun, 1997;Rodenburg et al, 2013). While it is generally believed that there is a negative correlation between range use and fearfulness, very few studies have investigated this association, and the relationship between range use, fearfulness and SFP is relatively unexplored.…”

Hypothalamic vasotocin and tyrosine hydroxylase levels following maternal care and selection for low mortality in laying hens

“…Feather pecking and cannibalism are concerning welfare problems in poultry farming, and a major topic of welfare research in laying hens [1-4]. Severe feather pecking compromises the victim’s welfare through physical pain and chronic fear, but also signals that the welfare of the perpetrator is being compromised, leading to the development of this maladaptive coping mechanism [5].…”