The Maintenance Requirements for Essential Amino Acids of Guangming No.2 Broilers
1 he study aimed to estimate the maintenance requirement for essential amino acids of Guangming No.2 broilers,and to provide a basis for the establishment of a prediction model of amino acid requirement.In trial 1,12 Guangming No.2 male and female were selected at 12 to 15 days of age and 31 to 34 days of age,respectively,with 6 replicates per treatment and 2 chick-ens per replicate.Each replicate was fed in a metabolic cage.The broilers were fed a nitrogen-free diet,and the excreta and shed feather dander of broilers were collected separately,and the ratio of endogenous nitrogen to shed dander nitrogen was calculated.In trial 2,48 male and 48 female broilers with similar body weight(BW)were randomly divided into 4 treatment groups(12 broilers in each treatment group),and male and female broilers were fed separately in 6 met-abolic cages.The four treatment groups were fed metabolic diets with different protein contents,and the excreta(including shed dander)of broilers were collected.Nitrogen deposition(nitrogen intake minus nitrogen expulsion)was calculated,a linear regression equation of nitrogen intake and nitrogen deposition was established to calculate the protein maintenance requirement of broil-ers.The maintenance requirement of endogenous protein and dander protein was calculated ac-cording to the ratio of endogenous nitrogen and shed dander nitrogen,and multiplied respectively by the composition of essential amino acids in endogenous protein(referring to previous data)and in shed dander protein(actual measurement)to calculate the maintenance requirements of endog-enous amino acids and dander amino acids,and the sum of the two was the maintenance require-ment of essential amino acids of Guangming No.2 broilers.Experimental 1 showed that the daily nitrogen loss of Guangming No.2 broiler was mainly due to dander shedding,which accounted for 55.9％～65.1％.There was a significant interaction between age and sex on the proportion of shed dander nitrogen to total nitrogen loss(P＜0.001),the proportion of shed dander nitrogen of male broiler was significantly lower than that of females in the early stage,but significantly higher than that of females in the later stage(P＜0.05).The second experiment showed that the intake,excretion and deposition of nitrogen increased significantly with the increase of protein content in metabolic diets(P＜0.001).The linear regression equations of nitrogen intake and deposition of male and female broilers were established in the two stages.The regression models were significant(P＜0.001),and the coefficient of determination were greater than 0.96.Ac-cording to the regression equation,the protein maintenance requirements of Guangming No.2 broilers were calculated,2.36 and 3.16 g/kg BW0.75 for male and female broilers at 12～15 days old per day,2.96 and 2.56 g/kg BW0.75 for male and female broilers at 31～34 days old per day.The utilization efficiency of dietary protein was 65.55％and 58.73％for 12～15 days old male and female broilers,79.42％and 73.95％for 31～34 days old male and female broilers.Accord-ing to the ratio of endogenous nitrogen and shed dander nitrogen obtained from experiment 1,the maintenance requirements of endogenous protein and dander protein in Guangming No.2 broilers at different stages were calculated.Then,according to the composition of essential amino acids in endogenous protein and dander protein,the maintenance requirements of endogenous amino acids and dander amino acids were calculated.In this study,an improved method was used to estimate the maintenance requirements of endogenous essential amino acids and dander amino acids in Guangming No.2 broilers,which provided a basis for the establishment of a prediction model of amino acid requirements.The estimated results of this study were close to those of adult chickens measured by the comparative slaughtering method,indicating that the proposed method was more reasonable than the original method.
Guangming No.2 broilergrowth stagegendermaintenance requirements for es-sential amino acid
万方数据
维普
