Effects of sex and dietary phosphorus level on the apparent metabolizable energy and nutrient digestibility in broiler chickens

The influence of sex of broilers and dietary phosphorus (P) level on energy utilization and apparent ileal digestibility of N, P and phytate-P were investigated. The AME(N) was determined using 3- and 6-week old broilers, while the apparent ileal digestibility were determined only with 6-week old birds. Sex of broilers had no effect on the AME(N) values determined during week 3. During week 6, the AME(N) values for male broilers were higher (P < 0.01) than those for the females. An interaction (P < 0.05) between sex and dietary P level was also observed. AME(N) values determined with male broilers were lower in the adequate-P diet compared to those in the low-P diet, whereas no effect of P level was observed in females. Female broilers tended (P < 0.10) to have a higher ileal N digestibility than the males, but a significant (P < 0.01) sex x P level interaction was observed. Males receiving the adequate-P diet had a lower N digestibility than those receiving the low-P diet, whereas the opposite was true in the females. Ileal phytate P degradation in males was higher than in females (0.282 vs. 0.234), but the differences were not significant. Increasing dietary P level increased ileal P digestibility in both the males and females, but the improvements were greater in the females, as indicated by a significant sex x P level interaction.