Changes in fear- and stress-related traits accompanying sexual maturity of female and male chickens
Tonic immobility duration and heterophil lymphocyte ratio were compared in mature and immature pullets and cockerels from two breeds of chickens (Castellana and Leghorn) at 24 wk of age. A total of 104 pullets and 120 cockerels were used, equally divided into two groups having early or late sexual maturity. Age at first egg in females and wattle size in males were used as indicators of sexual maturation. There were significant differences between groups of females in terms of tonic immobility reaction and heterophil to lymphocyte ratio (P < 0.01), mature hens showing shorter tonic immobility (218 ± 30 s) and higher leucocyte ratio (0.78 ± 0.04) than immature hens (400 ± 30 s and 0.51 ± 0.04, respectively). On the contrary, the duration of tonic immobility was significantly longer in the mature group of males (429 ± 24 s) than that in the immature group (177 ± 24 s), and the heterophil to lymphocyte ratio was not significantly different between groups of males (0.30 ± 0.04 and 0.33 ± 0.04, respectively). Thus, mature hens were less fearful and more stressed than immature hens, whereas mature males were more fearful than immature males, this change being not associated with stress. Mature females were less fearful than mature males but the opposite was true for the immature group, and females had higher leucocyte ratio than males in both mature and immature groups. A significant heterosis percentage for wattle size was found in the F1 cross between both breeds.
| Main Authors: | , , , |
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| Format: | journal article biblioteca |
| Language: | English |
| Published: |
Verlag Eugen Ulmer
1999
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| Subjects: | Hen, Cock, Behavior, Stress, Sexual maturity, |
| Online Access: | http://hdl.handle.net/20.500.12792/5643 http://hdl.handle.net/10261/295090 |
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