Early and temporary quantitative food restriction of broiler chickens. 1. Effects on performance characteristics, mortality and meat quality

1. An experiment was conducted with broiler chickens to determine the effec ts of different early food restrictions, strain (Ross 508 and Hybro G) and sex on performance, mortality; carcase composition and meat characteristics , 2. Birds were restricted to 80% or 90% of ad libitum intake for 4 d (80%-4 d-group and 90%-4 d-group, respectively) or 80% for 8 d (80%-8 d-group). Al l restrictions started on d 4. After the periods of restriction, all birds were fed ad libitum. 3. Only the 90%-4 d-group reached a final body weight not significantly dif ferent from, but lower than, the ad libitum group. The other restrictions w ere too severe to allow a sufficient 'catch-up'. 4. No significant differences in food conversion and total carcase fat cont ent between groups were observed. Abdominal fat showed a tendency to increa se due to the restrictions induced. 5. There was a slight trend towards a reduced mortality and of 'sudden deat h syndrome' but no clear effect of food restriction on number of chickens r emoved with leg problems. There was no significant decrease in uniformity o f the flocks due to restriction. 6. The group 80%-8 d had a significant lower yield percentage. Cut-up parts and meat quality were not changed by restriction. Ross birds had a signifi cantly higher proportion of breast meat than Hybro chickens. Meat of female chickens seemed to be paler than that of males, possibly because of the hi gher proportion of carcase fat. 7. Food restriction did not always give good results. However, a mild restr iction (90% for 4 d) may offer some economic advantages over an ad libitum feeding regimen, mainly by reducing mortality.