Broiler Apparent Metabolizeble Energy Determination Of Corns From Different Regions In China

Energy is the most expensive nutrient in poultry feed. Energy is the first limiting factor and to some extent already limits other mutrients to exert full potential, for example, essential amino acids. Corn is most important energy ingredient in China. ME contents of corn vary largely (often CV>10%) with varieties, areas of production, maturity, and batch. Soil condition, climate, storage, and processing technology also have effectc on the ME value of corn. In most cases, ME values of feed ingredients were calculated from regression equations based on the chemical composition and ME values of adult cock trials done 15 to 25 years ago. The values published by Chinese authority could not meet today`s feed and animal husbandry. This study was conducted to determine the exact substitution ratio of the tested corns in the substitution assay in broiler AME determination of corn, and broiler AME of 60 corns was estimated, then prediction equations were developed for AME of corn from defferent regions, so as to provide some basal data for Chinese nutrient and energy table and for the utilization of different corns in broiler production.Experiment 1. Study on Ratio of Tested Corn in the Mixed Diet by Extrapolation in Broiler ChickenThis experiment was conducted to determine the exact substitution ratio of the tested corns in the substitution assay by using the methods of extrapolation in broiler AME determination of corn. A total of 396 AA broiler chickens were raised to 28 days of age and randomly allotted into one of 9 different treatments consisted of 11 replicates with 2 male and 2 female each. Broiler chickens in different treatment were fed the tested diets substituted by different ratio of the tested corns (0,20%,30%,40%,50%,60%,70%,80% and 100%)in metabolizable experiment. It showed that the AME of the tested diets raised remarkably, while the AME of the tested corns were not significant different besides treatment 50% by the raising of tested corn ratio in basal diets(P>0.05). The AME value of the tested corn was calculated by the methods of Extrapolation. Put this value into the regression models established with the AME value of tested corn(Y) and its substitution ratio in basal diets(X), the corresponding X is 89.45% and 13.06%. However, bird performance was low at this ratio. Performance in the treatments replaced by tested corn on 20%~60% showed higher feed consumption and ADG, and the FCR had no significant difference (P>0.05). The variation of the AME value of the tested corns in replicates was small (<3%) in treatment replaced by 40% tested corn in the basal diet. It showed that 40% is practical ratio in broiler AME determination of corn by using the method of substitution. Experiment 2. Broiler Apparent Matabolizable Energy Determination of Corns from Different RegionsA metabolizable experiment was carried out using the total collection assay to determine the apparent metabolizable energy of 60 corns in broiler chicks. A total of 1220 AA broiler chickens of 28 days were randomly allotted into 61 different treatments consisted of 5 replicates with 2 male and 2 female each. One treatment was used as a basal diets, and the other 60 treatments were used to evaluate AME values of 60 corns from different regions by substitution assay (ratio of tested corn was 40%) at the same time. Chemical components and physical characters of 60 corns were also measured during the experiment. They were dry matter (DM), crude protein (CP), ether extract (EE), crude fiber (CF), nitrogen-free extract (NFE), neutral detergent fiber (NDF), crude ashes (CA), starch(STC), and volumetric weight (VW). The apparent metabolizable energy of the corns obtained by using 32~36 day-old broilers in this experiment varied a little. It was also stable. The determined figure could be used the refernce data of Chinese cornd.Experiment 3. Pridiction of Broiler Apparent Metabolizable Energy of Corns from Different RegionsThe study was to establish mathematical relationships between chemical or physical characteristics and broiler apparent metabolizable energy (AME) of corn from different regions. The chemical components or physical characters and broiler AME of 60 corns were tested in this experiment, and the optimal AME-components regression equations were established. Predict equation for broiler AME of 60 corns: AME=12.87-0.048DM+0.092CP+0.07EE-0.45CF-0.062NDF-0.36CA-0.0001VW+0.1057STC,R2=0.5339, P=0.0001. Predict equation for broiler AME of 17 corns from northeast region: AME=11.6790-0.04986DM-0.0324CP+0.0005EE-0.5165CF+0.0574NFE-0.1215NDF-0.9716CA+0.0775STC+0.0030VW, R2=0.8755, P = 0.0178. Predict equation for broiler AME of 11 corns from west region: AME=61.9753-3.7066DM+3.3935CP+3.3284EE+4.8107CF+3.5979NFE-0.8598NDF-0.3081STC,R2=0.7992,P=0.3571; Predict equation for broiler AME of 22 corns from huanghuai region: AME=20.4997-0.0386DM+0.06289CP+0.06198EE-1.2154CF-0.0444NDF-0.2356CA+0.0117STC-0.0002VW,R2=0.7096,P=0.0138;Predict equation for broiler AME of 10 corns from southchina region: AME=28.2677-0.1025DM-1.2056CF-0.1571NDF ,R2=0.7680,P=0.0248.