University of Life Sciences in Lublin, Lublin, Poland 1Centre for Nucleus Breeding “MESSA” , Cegłów, Poland 2Polish Academy of Sciences, Jastrzębiec, Poland
* Corresponding Author:
Tomasz Paweł Próchniak ,Tel: 0048 81 4456753, Fax: 7120103775, Email: email@example.com
Received: June 7, 2016; Revised: October 10, 2016. Accepted: February 4, 2017. Published online February 23, 2017.
The aim of the study was to evaluate genetic correlations between the behavioural profile and performance in laying hens as an indirect answer to the question whether the observed behavioural responses are associated with increased levels of stress in these birds.
The assessment of birds’ temperament was carried out using the Novel Objects Test. The behavioural test was conducted in two successive generations comprising 9483 Rhode Island White birds (approx. 4700 individuals per generation) and 4326 Rhode Island Red birds (approx. 2100 individuals per generation). Based on the recorded responses, the birds were divided into two groups: a fearful profile (1418 RIW hens and 580 RIR hens) and a brave/curious profile (8065 RIW hens and 3746 RIR hens). The birds were subjected to standard assessment of their performance traits, including SM- age at sexual maturity, ST – shell thickness, SG – egg specific gravity, EW – mean egg weight, IP – initial egg production, and PW/HC – number of hatched chicks. The lineage comprised a three-generation population of birds. Estimation of the components of variance of the behavioural traits was performed with Gibbs sampling (300000 rounds with 100000 burn-in rounds) based on the multi-trait animal model.
The analyses revealed negative correlations between the performance traits of the laying hens and the behavioural profile defined as fearful. In the group of fearful RIW birds, delayed sexual maturation (0,22) as well as a decrease in the initial egg production (-0,30), egg weight (-0,54), egg specific gravity (-0,331), shell thickness (-0,11), and the number of hatched chicks (-0,24) could be expected. These correlations were less pronounced in the RIR breed, in which the fearful birds exhibited a decline in hatchability (-0,37), egg specific gravity (-0,11), and the number of hatched chicks (-0,18). There were no correlations in the case of the other traits or they were positive but exhibited a substantial standard error, as for the egg weight.
Summing up the results obtained, it can be noted that behavioural responses indicating fearfulness, i.e. escape, avoidance, and approach-avoidance may reflect negative emotions experienced by birds. The negative correlations with performance in the group of fearful hens may indirectly indicate a high level of stress in these birds, especially in the white-feathered birds, where stronger performance-fearfulness correlations were found. Fearful birds should be eliminated from breeding by inclusion of the behavioural profile in the selection criterion in the case of laying hens.
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