Abstract:

【Objective】 The main objective was to investigate the effect of different dietary carbohydrate structure on fermentation and variation in amino acid profile of microorganisms in the rumen of goats, and to provide evidence for a global debate whether amino acids profile in the rumen microbes is constant or not.【Method】Four Xuhuai goats fitted with permanent rumen cannulas were used in a 4×4 Latin Square design experiment. Diets based on corn, soybean meal and rice straw were divided into 4 treatments according to ratio of nonstructural and structural carbohydrates (A: 0.33, B: 0.63, C: 1.17, D: 2.18). The experiment was conducted to determine the effect of dietary NSC/SC on rumen fermentation patterns and the amino acid profile variation of rumen microbes.【Result】 With the increase of dietary NSC/SC, there were some tendencies that the rumen pH decreased significantly (P＜0.05), NH3-N concentration in rumen increased significantly (P＜0.05). The percent of acetate decreased, the percent of propionate increased, and the ratio of acetate to propionate decreased in rumen significantly (P＜0.05) corresponding with the increase of dietary NSC/SC. Some amino acids concentration of rumen bacteria varied significantly (P＜0.05), such as Asp, Ser, Gly, Val, Met, Leu, Phe, His, Arg, and Pro. Different NSC/SC ratios also affected some protozoa amino acids, such as Asp, Ala, Leu, Phe, Lys, His, Arg, and Pro. 【Conclusion】 It is concluded that amino acid profile derived from rumen microbes is mainly variable with dietary carbohydrate structure in term of NSC/SC ratio.

Key words: carbohydrate structure, rumen fermentation, microbial amino acid profile