肉仔雞飼料原料可消化氨基酸和代謝能的生物學(xué)評定及可加性研究

yutaosl · 發(fā)表于 2011-4-6 09:27:29

Five experiments were conducted to study the additivity and biological value of digestible amino acid and metabolizable energy in corn, soybean meal, cottonseed meal, rapeseed meal for broilers.Experiment 1, 28-day-old AA broilers were randomly assigned into 8 groups (4 groups for male and female broilers respectively). Broilers were offered protein-free diet freely to determine the basal endogenous amino acid losses (BAAL) at the terminal ileum. The results were as follows: there were no significant differences between male and female broilers about BAAL and amino acid composition of endogenous protein (p>0.05). BAAL values of female broiler were greater than that of male broiler (p>0.05). Value of BAAL of Glu was the greatest (p>0.05), value of Asp was secondary, and value of His was lowest in 17 amino acids (p>0.05).Experiment 2, 192 28-day-old AA broilers were randomly assigned into 4 treatments, and were offered 4 diets, corn, soybean meal, cottonseed meal, rapeseed meal, respectively, to determine the ileal amino acid digestibility of amino acid. The results were as follows: ileal digestibilities of some AA were affected significantly by sex of broiler (p<0.05). SID and AID of His in male broiler were greater than that of female broiler (p<0.05) in corn. In rapeseed meal, AID and SID of Gly, Thr, Val of male broiler were greater than that of female broiler (p<0.05). There were no significant differences between male and female broilers about AID and SID of amino acid and CP in soybean meal and cottonseed meal (p>0.05).Experiment 3, this experiment was to determine whether the digestibilities of amino acid in a mixed diet for broilers were better predicted when based on SID or AID, and the additivity of ileal digestible amino acid were investigated. 384 28-day-old AA broilers were randomly assigned into 8 treatments. Eight diets were composed of corn, soybean meal, cottonseed meal, rapeseed meal and all diets were formulated to contain 20% CP. AID and SID of amino acid were evaluated. The results were as follows: for mixed diets containing corn, the measured AID for most amino acids were greater than the predicted AID (p<0.05), but no significant differences between predicted and measured values for SID were observed (p>0.05). For 3 mixed diets without corn, there were no significant differences between predicted and measured values for AID and SID (p>0.05). Values of AID and SID were additive in soybean meal, cottonseed meal and rapeseed meal in mixed diets for broilers.Experiment 4, 240 22-day-old AA broilers were randomly assigned into 5 treatments, with 8 replicates each treatment (4 replicates for male and female broilers respectively). Five diets were prepared based on corn, starch, soybean meal, cottonseed meal and rapeseed meal. AME and AMEn of corn, soybean meal, cottonseed meal and rapeseed meal were evaluated and TiO2 was made marker by collecting parts of excreta. The results were as follows: AMEn of male broiler was greater than that of female broiler in soybean meal and cottonseed meal (p<0.05). Sex of broilers had no significant effects on AME and AMEn in corn and rapeseed meal (p>0.05). The utilizable efficiency of AME and AMEn of male broiler were greater than that of female broiler in corn, soybean meal, cottonseed meal and rapeseed meal (p>0.05). AME of corn, soybean meal, cottonseed meal and rapeseed meal were 14.82, 12.10, 11.17, 9.79MJ/kg, and AMEn were 14.80, 11.81, 10.81, 9.60MJ/kg respectively.Experiment 5, this experiment was to study additivity of AME and AMEn for broilers by comparing differences between measured values for the mixed diets and predicted values from measurements of individual ingredients. 144 22-day-old AA broilers were randomly assigned into 3 treatments. Three diets were prepared by corn mixed soybean meal, cottonseed meal and rapeseed meal. The results were as follows: for AME and AMEn, and their utilizable efficiency, values of male broilers were greater than that of female broilers in corn-rapeseed meal (p<0.05). For AME and AMEn, and their utilizable efficiency, there were no significant differences between male and female broiler in corn-soybean meal and corn-cottonseed meal (p>0.05). There were no significant differences between AME and AMEn, and their utilizable efficiency in 3 mixed diets (p>0.05). There were no significant differences between predicted and measured values for AME and AMEn in 3 mixed diets (p>0.05). Results of the experiment demonstrated that AME and AMEn of broilers between corn and soybean meal, cottonseed meal, rapeseed meal were additive.