WELFARE ASSESSMENT OF BROILER BREEDER AND LAYER FEMALES SUBJECTED TO FOOD RESTRICTION AND LIMITED ACCESS TO WATER DURING REARING

1. A factorial experiment was conducted to assess the welfare at different ages of two strains of broiler breeder and one layer strain during rearing using a range of indicators. The birds were fed ad libitum or restricted and provided with free or limited access to water. 2. Food-restricted birds spent a large proportion of time scratching and pecking the litter compared with birds fed ad libitum. 3. The heterophil/lymphocyte ratio and the proportion of basophils were raised at 8, 12 and 16 weeks, and the plasma concentrations of corticosterone were higher at 8 and 12 weeks of age in restricted birds compared with those fed ad libitum. 4. Creatine kinase activity was higher in broiler breeders fed ad libitum compared with layers and 'restricted broiler breeders. The activity of aspartate transaminase was higher in restricted layers compared with birds fed ad libitum and was similar in broiler breeders. 5. Plasma viscosity was lower in food-restricted compared with ad libitum-fed birds. 6. Limiting access to water had little or no effect on the welfare indicators although food-restricted birds with free access to water spent more time drinking than birds fed ad libitum. 7. There were no important differences between the two broiler strains. Layers spent less time resting than broiler breeders and had higher plasma corticosterone concentrations at 3 and 16 weeks of age. 8. It was concluded that there was evidence for physiological stress associated with restricted feeding at least between 8 and 16 weeks of age. It was suggested that the altered behaviour of broiler breeders kept on litter may indicate that they can cope with food restrictions and that this may be acceptable in relation to the long-term benefits of limiting body weight during rearing. The same may not be true for layers: