Effects of Different Replacement Ratios of Soybean Meal on Its Metabolizable Energy and Nitrogen Metabolism in Broilers
[Objective]The study was conducted to investigate the effects of different replacement ratios of soybean meal(SBM)on its metabolizable energy and nitrogen metabolism in broilers.Furthermore,the relationship between uric acid and digestible nitrogen with soybean meal apparent metabolizable energy(AME)were analyzed for providing references for accurately measuring the metabolizable energy of feed ingredients.[Method]A completely randomized design was adopted,and the replacement ratio of SBM was treated as a single variable.A total of 216 broilers at aged 22 days were randomly divided into 6 groups,with replacement ratios of SBM at 10%(SM10),20%(SM20),30%(SM30),and 40%(SM40),while the other two groups were the basal diet 1 and basal diet 2.Each experimental diet was allocated to 6 replicates of 6 broilers per replicate.Metabolic trials were conducted on broilers aged 22-28 days.The total collection method was used to collect all excreta of each repetition as the experimental unit,the energy and protein content in both the feed and excreta matter and uric acid content in excreta were determined.These data were then used to analyze the relationship between uric acid and AME and nitrogen-corrected apparent metabolizable energy(AMEn)of soybean meal.[Result](1)Soybean meal replacement ratio had no significant effect on the total energy intake of broilers(P＞0.05),but had a significant effect on the total energy output of broilers(P＜0.05).As the soybean meal replacement ratio increased,the AME and AMEn of diets decreased significantly(P＜0.05).(2)With the increase in soybean meal replacement ratio,the protein intake,protein output,uric acid excretion,retained nitrogen,and digestible nitrogen in broilers were significantly increased(P＜0.05).(3)As the soybean meal replacement ratio increased,there was a significant increase in the output of uric acid per unit of protein intake(UAO/PI,g·g-1,%)(P＜0.05),as well as an increase in the excretion of uric acid nitrogen per unit of digestible nitrogen(UAN/DN,g·g-1,%)(P＜0.05).A significant linear relationship was observed,with increasing SBM replacement ratios leading to a decrease in AME and AMEn(P＜0.05).(4)A strong negative correlation was observed between UAO/PI and UAN/DN with the AME and AMEn of SBM(R2＞0.90,P＜0.05).[Conclusion]The tested soybean meal replacement ratios significantly affected nitrogen metabolism and metabolizable energy measurement in broilers.There was a significant negative correlation between uric acid excretion and metabolizable energy,so which make uric acid nitrogen a potential indicator for optimizing the metabolizable energy system.
broilersreplacement ratiouric acidmetabolizable energy
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