Comparison of the tonic immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry of chicks reared with or without a broody hen, and of broody and non-broody hens

摘要

The purposes of this study were to determine whether rearing with a broody hen influenced duration of tonic immobility, heterophil to lymphocyte ratio, and relative fluctuating asymmetry of chicks and to analyze the differences between broody and non-broody hens in fear and stress indicators. A total of 120 chicks (60 reared with a broody hen and 60 reared without a broody hen), and 48 hens (24 broody and 24 non-broody) were analyzed at 6 and 52 weeks of age, respectively. Broody hens were observed in 12 different Spanish breeds (Blue Andaluza, Black-barred Andaluza, Black Red Andaluza, Black Castellana, White-faced Spanish, Buff Prat, White Prat, Birchen Leonesa, Quail Castellana, Quail Silver Caste liana, Red-barred Vasca, and Red Villafranquina), and all the chicks were from an F-1 cross between the Black-barred Andaluza and the Black Castellana breeds. Tonic immobility duration was significantly longer (P < 0.0001) in chicks reared without a broody hen than in those reared with a broody hen, suggesting that the presence of a broody hen reduces fear in chicks. There were no significant differences in the heterophil to lymphocyte ratio and the relative fluctuating asymmetry of leg length, leg width, and toe length, although the fluctuating asymmetry of wing length and the combined fluctuating asymmetry value of the 4 traits tended to be significant. These results suggest no effect on stress in chicks in the presence of a broody hen. Tonic immobility duration and heterophil to lymphocyte ratio were similar in broody and non-broody hens, indicating no association of broodiness with the fear and stress levels in hens. In conclusion, the presence of a broody hen during rearing has significant effects on fearfulness of chicks; rearing chicks with a mother being a method to reduce this major behavioral problem. However, broodiness was not associated with fear and stress indicators in hens