Effect of the presence of males on three measurements of fear and stress of females in several breeds of layers
The purpose of this study was to analyze the effect of the presence of males on three measurements of fear and stress in females of several breeds of layers at 22 wk of age tonic immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry of four bilateral traits (toe length, wing length, leg length and leg width). A total of 240 females from four Spanish breeds (Black Castellana, Buff Prat, Red-Barred Vasca, and Red Villafranquina) and a synthetic breed (Quail Castellana), that were reared in an all-litter house with or without the presence of males from 8 to 22 wk of age, were used. The effect of the presence of males on tonic immobility duration was not significant, indicating that the presence of males is not associated with the fearfulness of females. There were significant differences for heterophil to lymphocyte ratio (P < 0.05), the values being higher in females reared with the presence of males. There were significant differences in fluctuating asymmetry of toe length and leg width (P < 0.05), being greater in females reared with males. The interaction between group and breed for the combined fluctuating asymmetry of the four bilateral traits was significant (P < 0.05). The combined fluctuating asymmetry was greater for females reared with males in all breeds, the difference being significant in the Buff Prat, Quail Castellana and Red Villafranquina breeds. Results for heterophil to lymphocyte ratio and fluctuating asymmetry suggest that females in flocks containing males have more stress. Thus, an early exposure to the opposite sex may be unfavourable, bearing in mind that the early social experience will have important effects on adult behavior, and it should be advantageous to raise females without males in commercial situations for layer breeding stocks. © Verlag Eugen Ulmer, Stuttgart.
| Main Authors: | , , |
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| Format: | journal article biblioteca |
| Language: | eng |
| Published: |
2013
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| Online Access: | http://hdl.handle.net/20.500.12792/6035 |
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