1. Ruminal degradability and intestinal digestibility of individual amino acids in mixed diets with different crude protein levels measured by the modifiedin vitrothree-step and mobile nylon bag technique
- Author
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Bowen Zhang, Wei Gao, Daofu Chen, Bo Lv, and Chenli Liu
- Subjects
0301 basic medicine ,chemistry.chemical_classification ,Methionine ,Chromatography ,0402 animal and dairy science ,Tryptophan ,04 agricultural and veterinary sciences ,General Medicine ,040201 dairy & animal science ,Amino acid ,03 medical and health sciences ,chemistry.chemical_compound ,Rumen ,030104 developmental biology ,chemistry ,Dry matter ,Food science ,Proline ,General Agricultural and Biological Sciences ,Digestion ,Histidine - Abstract
The ruminal degradability and intestinal digestibility of dry matter (DM), crude protein (CP) and amino acids (AA) in three total mixed rations with different CP levels were estimated using the modified in vitro three-step procedure (TSP) and mobile nylon bag (MNB) technique on growing lambs. The ruminal effective degradability of DM and CP did not respond with increasing dietary CP level. However, the intestinal digestibility of DM was significantly increased with increasing dietary CP level estimated by TSP (P < 0.05) or MNB method (P < 0.01). Intestinal digestibility coefficients of CP determined by TSP were lower than those of the MNB method. Histidine was extensively degraded by rumen micro-organisms, while tyrosine was the most anti-degradable AA among the samples. The ruminal AA degradability exhibited no significant differences except for threonine, tryptophan, alanine, aspartic acid and proline for the three diets. Similarly, only a few AAs (i.e. histidine, methionine, tryptophan, aspartic acid and cysteine in TSP; histidine, tryptophan, aspartic acid and serine in MNB) had significant differences in their intestinal digestibility; in addition, values of MNB were lower than that of the TSP method, indicating that intestinal digestibility of DM seems to be overestimated in TSP, while that of CP might be overestimated in the MNB method.
- Published
- 2015