Sexual dimorphism in broilers following periods of equal water and feed intake

A study involving three experiments was conducted to investigate patterns of feed and water intake following an initial period in which both sexes received the same water or feed allowance. Restriction of water to an equal intake level in males and females from 0 to 10 days resulted in similar feed intake patterns and similar body weights for both sexes. Following exposure to ad libitum water, males immediately consumed 7 to 11% more water than females, while the accompanying change in feed intake was smaller in magnitude (1 to 6%). Restriction of feed to equal intake levels in both sexes from 0 to 12 days resulted in males and females consuming similar amounts of water. Body weights of males were slightly greater than female weights due to differences in feed efficiency. Following placement under ad libitum feed, males consumed more feed than females (8 to 9%). However, the divergence in feed intake following feed restriction between sexes was more gradual than the divergence in water intake following water restriction. These data indicate that feed and water intake patterns of males and females are controlled by inherent mechanisms independent of differences in body weight or maintenance requirements.