a1 Department of Animal Science, University of Ife, Ile-Ife, Nigeria
Two strains of commercial layers, 42 weeks old, were fed ad libitum, 85 and 70% of ad libitum for five 28-day periods to study the effects of feed restriction on body weight, carcass characteristics, laying performance and mortality. There were highly significant strain effects on all traits (P < 0·01) except dressing percentage. Period differences were also observed for egg production, egg weight and feed efficiency. In addition, in all cases the relationship between period and these traits was non-linear and was affected by strain or treatment.
Feed restriction had significant effects (P < 0·01) on all traits except dressing percentage and mortality. Feed restriction to 70% of ad libitum reduced egg production, egg weight, body weight and feed consumption and improved feed efficiency. However, in most cases there was no difference between ad libitum feeding and 15% feed restriction.
Strain × treatment interaction had significant effects on egg production and feed efficiency.
(Received October 04 1980)