Behavioural, endocrine and metabolic effects of food restriction in broiler breeder hens

The effects of food restriction on behaviour, endocrine and metabolic param eters were studied in immature (13 weeks old) female breeding birds of the meat-type chickens (broiler breeders). Ad libitum fed hens were compared wi th those subjected to one qualitative (diet diluted with 30 % hardwood sawd ust) and two quantitative (the daily ration recommended by the breeding com pany and twice that amount) food restriction treatments. Behaviour of quant itatively restricted hens provided with one daily meal showed marked diurna l variation, while that of hens with free access to food (ad libitum fed an d qualitatively restricted) was more evenly distributed throughout the day. There were elevated plasma corticosterone concentrations in hens subjected to intensive quantitative restriction. Although an increase in corticoster one concentrations of liens subjected to qualitative food restriction was l ower, it was significant in comparison with ad libitum control, indicating that even mild qualitative food restriction is stressful. Compared to ati l ibitum fed hens, there were decreased plasma T-3 concentrations in all food restriction treatments, while plasma T-4 concentrations increased in inten sively quantitatively restricted hens. Food restriction did not affect plas ma glucose and total proteins, whereas triacylglycerol levels were decrease d and cholesterol increased as a consequence of restriction. Creatinine lev el was increased in hens with less intensive quantitative restriction and p lasma concentration of uric acid was decreased in qualitatively restricted hens in comparison with all other treatments. These results suggest that al though behaviour of qualitatively restricted-fed hens resemble more to that of rid libitum-fed hens, their physiological status reminds more quantitat ively restricted ones.