Strain differences in aggressiveness of male domestic fowl in response to a male model

Abstract

The objective of this experiment was to determine if the unusually high levels of aggression shown by male broiler breeder domestic fowl towards females is due to a higher overall level of aggressiveness in this strain. We compared the aggressive behaviour of broiler breeder (BR) males with that of males of an Old English Game strain (GA) which had been bred for fighting. Also, by rearing males of a commercial laying strain (LR) under the same level of feed restriction recommended for broiler breeder males, we examined the effects of feed restriction during rearing on aggressive behaviour at maturity. Full-fed commercial laying strain (LA) males were used as a control. The behaviour of individual males, nine from each treatment group, towards a model of a male conspecific was recorded for 15 min. The test was repeated 4 weeks later, after the males had received some limited sexual experience. Game strain males reacted most aggressively to the model, waltzing ( P<0.001) and crowing ( P<0.05) more than males from the other treatment groups which did not differ significantly from each other. Waltzing and crowing also increased significantly from the first to the second test in GA males ( P<0.005), but not in males from the other treatment groups. Frequency and duration of ground pecking was significantly less in BR males than in GA or LA males ( P<0.005) and significantly less in GA and LA males than in LR males ( P<0.05). Frequency of wing flapping was significantly greater in BR and LR males than in GA or LA males ( P<0.005). In conclusion, broiler breeder males did not behave aggressively towards a male model relative to game strain males. Whereas feed restriction during the rearing phase did affect behaviour of adult males, aggressiveness towards a male model did not increase.