Effect Of The Dietary Protein Level And Supplementation Of Urea On Endogenous Amino Acid Losses Of Broiler

The endogenous amino acid losses(EAAL) of the broilers, which were force-fed various diets different in protein level and supplemented with 0.1% urea, were determined using the method of simplified Single Intravenous Injection of [3H] Leucine (SIIL).35 AV broilers (avg. 1.50kg body weight) were randomly divided into 7 groups, received seven kinds of diets respectively. The diets were nitrogen-free diet (NFD), diets with 16%, 18% ,20% crude protein (CP) and CP16+U (0.1% urea) , CP18+U, CP20+U. After force-fed in 25g DM per kg BW, 30u Ci[3H]Leu/kgBW was injected subcutaneously, the excreta in the following 48hr were totally collected, and venous blood samples were taken at 24 hr. AA and CP content in diets ,excreta and blood sample were detected , radioactivity of excreta and non-protein-plasma were as well as. After the endogenous losses of Leu were determined by SIIL method , other AAs' endogenous losses could be got with NFD model, then calculated the apparent and true digestibility of AA and CP in various diets.The main results were as follows:1 The EAAL does not differ significantly (P>0.05) when broilers received diets different in CP levels. The endogenous losses of ?AA was 13666.40 mg/kg DMI 48hr when broilers fed NFD, and it increased significantly (P=0.045~0.057) when broilers fed CP16, CP18 and CP20 diets respectively, expressed as 19503.21, 16253.85, 19529.10 mg/kg DMI 48hr. EAAL was not significant (P>0.05) among three CP levels, but it had a decreased tendency in CP 18% diet (down 16.7% in numeric).2 The EAAL does not differ significantly (P>0.05) when broilers fed supplementation of 0.1% urea in different CP levels. The endogenous losses of ?AA were 18545.13 18147.08 18977.26 mg/kg DMI 48hr when CP16, CP18, CP20 diets adding 0.1% urea, respectively.3 The ADAA seems to be a square curve when broilers fed CP16, CP18 and CP20 diets, and the data were highest in CP18% diet. At the same time, the TDAA were decreased straightly (P>0.05). Supplementation of 0.1% urea in diets reduced the ADAA and TDAA (P=0.045~0.080).