Effects of sex, age and food intake upon metabolisable energy values in broiler chickens

1. Nitrogen-corrected apparent metabolisable energy (AME[n]) values of 2 diets with different energy:protein ratio were estimated in an experiment with 8 groups of female and 8 of male chickens in 15 sequential 3-day balance periods from the 12th to the 56th d of age. 2. The effect of sex on AME(n) values was not significant. 3. The effect of age was highly significant. AME(n) values of the mixture with the narrower energy:protein ratio increased with age. The dependence of AME(n) of the diet with the wider energy:protein ratio on age was parabolic, AME(n) values increasing only until the 37th day of life. 4. Under conditions of ad libitum feeding, AME(n) of the mixture with the wider energy:protein ratio given to female chickens decreased significantly with increasing food intake.