Effect of age on digestibility of starch in chickens with different growth rate

Abstract

Digestibility of starch was examined in slow-growing cockerels of laying type (SG) and in fast-growing male chickens (FG) of broiler type fed ad libitum on a maize-type diet until Day 22 of age in one-day periods and from Day 22 to Day 100 in three-day periods. Digestibility was estimated using the chromic oxide indicator method. In SG chicks, starch digestibility rapidly increased within the first days of their lives and reached the value of 0.986 already on Day 4 of life. It was maintained on this level till the end of the experiment, which was finished at the age of 100 days. In FG chicks, which in comparison with SG birds consumed more than a double quantity of feed, high starch digestibility was observed as late as on Day 8. From Day 8 to Day 100 of age, starch digestibility slightly but highly significantly (P < 0.01) decreased. The average value of digestibility was lower by 0.008 in broiler type chickens than in SG chickens at this time; nevertheless, digestibility was never below 0.96. The difference was highly significant (P< 0.001).