title: The effect of dietary methionine levels on endogenous nitrogen and endogenous amino acids flows in growing goats.
abstract: The effect of dietary methionine (Met) levels on endogenous N and amino acids (AA) flows at different part of the digestive tract of growing goats was determined using a (15)N isotope dilution technique. Three goats (25 ± 2.5 kg) were fitted with the ruminal, duodenal and ileal cannulae and allocated to three dietary treatments in a 3 × 3 Latin square design. The dietary treatments consisted of a total mixed ration containing three levels of Met (0.15%, 0.25% and 0.35%) respectively. It was found that at 0.15% Met level, the lowest flow in endogenous N and total AA at the duodenum and ileum occurred. The endogenous N secretion contributed to 26% and 23% of the duodenal and ileal total N flows, respectively, and the proportions were not affected by the dietary Met levels. The duodenal and ileal flows of endogenous total AA were 11.1, 11.8, 11.3 g/d and 2.9, 3.9, 4.1 g/d respectively. The average real digestibility of N was 65%, 87% and 95% in the forestomach, intestine and whole digestive tract respectively.
authors.affiliation: Key Laboratory of Agro-ecological Process of Subtropical Region, Institute of Subtropical Agriculture, the Chinese Academy of Sciences, Changsha, Hunan, China.
authors.forename: C S
authors.initials: CS
authors.lastname: Zhou
authors.forename: Z L
authors.initials: ZL
authors.lastname: Tan
authors.forename: S X
authors.initials: SX
authors.lastname: Tang
authors.forename: Z H
authors.initials: ZH
authors.lastname: Sun
authors.forename: X F
authors.initials: XF
authors.lastname: Han
authors.forename: M
authors.initials: M
authors.lastname: Wang
authors.forename: G O
authors.initials: GO
authors.lastname: Tayo
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D004386:Duodenum / Q000378:metabolism; D006041:Goats / Q000254:growth & development*; D008715:Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D008715:Methionine; D009584:Nitrogen