A 2 × 3 factorial arrangement of treatments with two ages of broilers (11 to 14 or 25 to 28 d of age) and three samples of feed ingredients was utilized to compare metabolizable energy (ME) and ratio of ME to gross energy (GE) in each group of three cereal grains (CG, including one corn, two wheat flour), three oilseed meals (OM, including one soybean meal, one peanut meal, and one cottonseed meal), three corn gluten meals (CGM A, B, and C), and three feather meals (FM A, B, and C). Each treatment contained six replicates of four Arbor Acre male broilers in energy balance experiments. Trends toward interactions between age and source of CG were observed on the ME and ME/GE of CG (0.05 <P < 0.10). The ME and ME/GE in corn were greater for broilers from 25 to 28 than for 11 to 14 d of age (P < 0.05). However, the ME and ME/GE in wheat flour A and B were not affected by the age of the broilers. The ME and ME/GE of OM were not affected by the age of broilers but differed across sources (P < 0.01). Conversely, the ME and ME/GE of FM were not different across sources of FM, but the ME and ME/GE of FM were less for broilers from 11 to 14 compared to 25 to 28 d of age (P < 0.01). Significant interactions between age and sources of CGM affected the ME and ME/GE of CGM (P < 0.05). The ME and ME/GE of CGM A were greater than CGM B (P < 0.05) when fed to broilers from 25 to 28 d of age but there was no effect from 11 to 14 d of age. The ME and ME/GE of CGM were less in broilers from 11 to 14 compared to 25 to 28 d of age (P < 0.05). These results indicate that the energy value of wheat flour and OM are similar regardless of age, but the ME in starter diets with corn, CGM, and FM may be overestimated if the ME values are obtained from growing broilers.
Keywords: age; broiler; feed ingredient; metabolizable energy.
Databases lack true information on metabolizable energy (ME) values of feed ingredients for broilers across phases. The current study evaluated the effect of broiler age (11 to 14 d or 25 to 28 d) on ME of three cereal grains (CG, one corn, two wheat flour [WF]), three oilseed meals (OM, one soybean meal, one peanut meal, and one cottonseed meal), three corn gluten meals (CGM, three sources of CGM differed in crude protein content), and three feather meals (FM, one enzymatical hydrolyzed FM, one expanded FM, and one hydrolyzed FM). Our study demonstrated no interactive effects between broiler age and source of feed on ME of OM and FM, but detected interactive effects for CG and CGM. Thus, the effect of age on ME can depend on the type of feed and its chemical composition. In addition, the ME of WF and OM was not affected by age, but the ME of corn, CGM, and FM increased as broilers aged. These results indicate that the ME in starter diets with corn, CGM, and FM may be overestimated if the ME values of feed ingredients are obtained from growing broilers.
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