Comparative Research On The Enzyme-hydrolyzed Casein And Difference Method For Determining True Digestibility Of Amino Acids And Endogenous Amino Acids Losses With Growing Drakes

The experiment was designed to study the difference of enzyme-hydrolyzed casein (EHC) and difference method (DF) for determining True Digestibility of Amino acids(TAAAs) and Endogenous Amino acids Losses (EAALs) of Animal fed on normal Protein-containing diets. The difference method was conducted with 32 tianfu meat drakes (7 weeks old , 2.77±0.16Kg , Live-weight) , based on soybean-meal , two different crude protein(CP) level(15%, 20%) were formulated; The enzyme-hydrolyzed casein method was conducted with 16 tianfu meat drakes(7 weeks old , 2.77 ± 0.17Kg ,Live-weight) .based on enzyme-hydrolyzed casein-meal, one crude protein(CP) level (17.5%) was formulated; Non-protein diets(NFD) method was conducted with 16 tianfu meat drakes (7 weeks old , 2.76 ± 0.17Kg , Live-weight) . Each experimental diet had 4 replicates of 4 drakes, The crude fiber (CF) all diets were kept all constant, Drake were force-fed respective trial diets according to Sibbald method. The EAALs was also measured from non-protein diets(NFD), and the comparison was made among the values from different methods.The results showed that TAAAs and EAALs measured from EHC, DF and NFD were 1.2243mg/gDMI, 0.9946 mg/gDMI and 0.9297 mg/gDMI respectively; The TAAAs(%) measured from DF was 88.81+4.53. Amino acids true digestibility(%) of different protein levels according to enzyme-hydrolyzed casein and Nitrogen-free diet method were(average value of 15% and 20% protein levels) 91.56 + 4.22 , 88. 69±4. 33 respcetvely. The EAALS from DF were keep constant under the range of CP 15~20%. The EAALS were 0. 9972mg/gDMI and 0.9919 mg/gDMI under the 20% and 15% CP levels respectively. The average of the values on EAALs and TAAAs by EHC was higher(P<0. 05) by 19.5%, 24.8% than those from DF and NFD respectively. The average of the values on EAALs by DF was higher(P<0. 05) by 6.57% than NFD. The average of the values on TAAAs by DF and NFD were similar(P>0. 05).Under the conditions of the present experiment . It was conclude, Using DF to determining the availability of amino acids and endogenous amino acid losses of animal fed normal protein-containing diets is feasible. While the enzyme hydrolyzed-casein may overestimate the availability of amino acids and endogenous amino acid losses of animal.