Nutrient utilisation, metabolisable and net energy values of corn for broiler chickens during the starter and grower phases.

The objective of this experiment was to determine the energy values and nutrient utilisation of five corns at starer (14-16 days) and grower (28-30 days) phases. The 1-5 corn samples were obtained from Jinzhou, Liaoning; Gongzhuling, Jilin; Qingdao, Shandong; Songyuan, Jilin and Xinxiang, Henan, China. Each phase of the trial consisted of six treatments with six replicates each. The number of birds per replicate was 4 (Days 14-16) and 2 (Days 28-30). Diets included a corn-soybean meal basal diet and five test diets contained 30% of each corn sample, which replaced 30% of the energy-yielding components of the basal diet (as-fed basis). The trial consisted of six cycles, each cycle was 7 days, including 4 days for adaptation to feed. On Day 4, the birds were transferred to the respiration chambers. In the following 3 days, total excreta were collected and daily heat production was measured. The apparent total tract retention of dry matter, crude protein, ether extract, and starch improved with age, showing the same trend as energy values. The nitrogen-corrected metabolisable energy (AMEn) values for corn samples at the starter phase were in the range of 16.25-17.41 MJ/kg DM and at the grower phase were in the range of 17.23-17.60 MJ/kg DM. On the other hand, the net energy (NE) values of the five corn samples ranged from 9.93 to 11.67 MJ/kg DM during the starter period and from 11.19 to 12.27 MJ/kg DM during the grower period. The AMEn and NE values of the five corn samples were close to the literature values for corn. Results from our research indicated the nutrient digestibility and energy values of corn samples increase with the age of the broiler.