Level of stress in relation to emotional reactivity of hens

Abstract

The aim of the study was to associate behavioural reactions of laying hens with the level of stress and to answer the question whether it is possible to select reactions that will facilitate phenotypic assessment of the level of stress in these birds. The investigations were carried out in 50 Green-legged Partridge, 50 Polbar and 50 Leghorn birds. A modified open-field test (MOFT) and a tonic immobility test were applied. Next, the quality of feathers was evaluated and the level of corticosterone in the feathers was determined. The corticosterone level was assessed in relation to the genetic group and feather quality and in relation to the probability of the presence/absence of specific physiological–behavioural reactions. The analysis of the results revealed no correlations between the corticosterone level in the feathers and the quality of the feathers. In turn, there was a correlation between the hen breed and the corticosterone level in the feathers: a significant difference was found between Zk and Pb hens. It was demonstrated that the corticosterone level was significantly higher in birds that exhibited such behaviours as preening in the open-field test. To sum up the results, it can be concluded that such behaviours as feather preening and latency until tonic immobility occurs can be indicators of stress in laying hens.Highlights There was a correlation between the breed and the corticosterone level in the feathers: there was a significant difference between the Green-legged Partridge (3.97 ± 0.17) and Polbar (4.50 ± 0.19) hens. No significant correlations were found between the corticosterone level and the behavioural reactivity in the analysed hens. It was demonstrated that the corticosterone level was significantly higher in birds that exhibited self-grooming behaviours in the open-field test (4.61) than in hens that did not show such behaviours (3.91).

Keywords

• corticosterone
• feathers
• emotional reactivity
• behavioural tests