Comparision Of Estimatation For Endogenous Amino Acids Losses In Roosters

The amino acid digestibility is the vital index in the evaluation of nutrient value andavailability, and how to estimate EAAL accurately is the precondition of calculating digestibleamino acid in feedstuffs.It lays the foundation for the precise formulation in animal diets. Theendogenous amino acids losses is inevitable in the digestion process. The method ofdeterming EAAL has always been the focus of research, and it is difficult to separate theunabsorbed protein derived from exogenous feeds and the compounds from Endogenoussecretion. Methods for determing the EAAL existing have their own merits and drawbacks,they all based on some hypothesis. People are looking for a preferable method to estimate theEAAL when aminals accepted a real diet containing protein.The current study is to evaluatethe comparision of methods for accurately determining the endogenous amino acids losses(EAAL). Firstly, the NFD method, Regression method and Protein gradient difference methodwere used to estimate the EAAL and amino acid digestibility in caecectomized rooster withsoybean meal as the only peotein in diets for animals. Seven crude protein levels were allottedto42caecectomized roosters randomly, including0,3%,6%,9%,12%,15%,18%,respectively. Results were as follows:1. The total endogenous amino acids losses by Gradient difference method wassignificant higher than Regression method and NFD method (P<0.05), which were17796.7mg/kg DMI,12825.2mg/kg DMI and9960.5mg/kg DMI, respectively.2. The apparent digestibility of total amino acids showed a significant linear effect withthe increasing dietary crude protein level (P<0.001). The standardised amino acid digestibilitycorrected by NFD method and Regression method was similar(P＞0.05), the true amino aciddigestibility aclculated by Gradient difference method, which is94.05%, showed more closedto100%than that by NFD and Regression method.3. The effects of dietary crude protein levels on EAAL in precision fed cecectomizedroosters increased significantly (P<0.05). The compositions of EAAL in different CP level issimilar, which indated that the EAAL has constant origins, the different EAAL of different CPlevel attributes to their quantities affected by the protein content.The current study demonstrated that, when the dietary CP level is low (0~6%), the gradient difference method resulted similar EAAL with the NFD method and the regressionmethod. Nevertheless, poultry was accepted actual diets with high protein level (6%~18%),the gradient difference method can estimate the real EAAL including basic and dietary specialendogenous amino acid losses. In addition, dietary crude protein content may increase theEAAL amount, but the same protein had a constant endogenous AA composition.