Methodology Of Determining Endogenous Nitrogen And Endogenous Amino Acids Labeled By¹³C Originated C₃and C₄Plants In Goats

Order:Utilizing the stable isotope13C enriched naturally in C3and C4plants as the marker, to establish a new determining methods on endogenous nitrogen (EN) and endogenous amino acids (ENAA) losses in the digestive tract in ruminant, then to improve the measurement methodology of EN and ENAA losses in ruminant.Methods:This study consists of experiment1and experiment2. In experiment1,20healthy castrated male goats were randomly divided into two groups C3and C4, which were fed two kinds of diets composed of C3and C4plants respectively. Two goats were selected randomly from each group to be slaughtered at0,4,8,12and16weeks, and took the blood, longissimus muscle, hair, intestinal tissue and intestinal epithelial tissue as the experimental samples. Then13C abundance of total amino acids in tissue samples and feed were determined to confirm the stable marked rate in goats. In experiment2,12healthy castrated male goats as experimental animals were randomly divided into two groups fed C3and C4diets respectively,6goats (3goats/group) with the ruminanlly, duodenally and ileally fistulas were used to determine the apparent digestibility of N and AA in terminal ileum by Cr2O3, the13C abundance of total amino acids in feed, chyme with separation of microorganism and tissue were determined, then the related functional relationship between the13C abundance of amino acids in different tissues and EN and ENAA excretion were established, to gain the correction factor of EN and ENAA excretion among tissues in the duodenum and ileum according to the different functional relation.Results:(1) There were no significant differences in the goats’growth performance and carcass traits between C3and C4group;(2) The equilibration time of13C isotope enriched in C3and C4plants in different goat tissues were12weeks;(3) Endogenous amino acid flow in duodenum and ileum of C3group was higher than C4group (P<0.05), which was calculated by hair, muscle, rumen epithelium and rectal epithelial as precursor pool; There were no significant differences among endogenous nitrogen flows in duodenum and ileum calculated by different tissues as precursor pool (P>0.05);(4) Establish the functional relationship between different precursor pools (muscle, intestinal epithelial) and target tissues which were blood and hair.Conclusion:Take isotope13C enriched naturally in C3and C4plants as a marker to determine endogenous nitrogen and endogenous amino acids in the ruminant digestive tract, the results is dependable because of animals’ normal physiological status, while this method has the advantages of convenient and economically viable.