Effects of feed restriction during the laying period on the performance of two strains of mature caged commercial layers in the humid tropics

SUMMARY Two strains of commercial layers, 42 weeks old, were fedad libitum, 85 and 70% ofad libitumfor 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% ofad libitumreduced egg production, egg weight, body weight and feed consumption and improved feed efficiency. However, in most cases there was no difference betweenad libitumfeeding and 15% feed restriction. Strain × treatment interaction had significant effects on egg production and feed efficiency.