| The experiment was conduct to study the effects of different amount of tannins in residue of tea-leaves on degradation ratio of feed protein in rumen of sheep and the protection of dietary protein, this study contained two tests.In Experiment 1, The experiment used residue of green tea (Xinyang Maojian), scented tea and mixed residue of tea-leaves from tea house and restaurant as sample to determine the content of tannins, condensed tannin and crude protein. The air dried residue of tea-leaves and high-protein soybean meal (CP 41.73%) were mixed in different proportion, a total of 6 treatments called A,B,C,D,E,F. The ratio of tea residue and soybean meal were 0:10, 1:9, 2:8, 3:7, 4:6, 10:0. This experiment used 6 test materials as samples to measure the degradation ratio of DM and CP with the method of rumen fluid in vitro and rumen fluid + HCl-pepsin. Result shows that the content range of crude protein, crude fiber, TAE and CT determined were 23.23～28.11%, 16.68～17.84%, 1.98～2.10%, 1.47～1.57%respectively; the degradation rate of dry matter of treatment A to F in one step and two-step test were 25.67～61.39%, 26.47～79.61% respectively, and the degradation range of crude protein were 16.68～60.76%, 17.69～84.85% respectively, additionally, the degradation rate of dry matter and crude protein were significantly different (P﹤0.01).In Experiment 2, Four High Mountain Fine-wool wethers (one and a half years old and average live weight of 29±2.55kg) fitted with permanent rumen fistula were used in this experiment. With a 4×4 Latin square design, the experiment was carried out to study the effects of 4 different tannin contents of diet on digestion of nutrients and nitrogen metabolism parameters in sheep diets, separately, diet A ( the control) 0.00 g﹒kg-1 DM; diet B, 1.02 g﹒kg-1 DM; diet C, 2.04 g﹒kg-1 DM; and diet D, 3.06 g﹒kg-1 DM. Correspondingly, the condensed tannin contents were 0.00, 0.765 , 1.53, and 2.30 g﹒kg-1 DM, respectively. Results showed that residue of tea-leaves at high proportion affect the feed intake, compared with diet A and B, the DMI and OMI of diet C (P﹥0.05) and diet D (P﹤0.01) were lower, the tannin contents in residue of tea-leaves among four diets have no significant (P > 0.05) effect on the digestibility of DM, organic matter (OM), acid detergent fiber (ADF) neutral detergent fiber (NDF), nitrogen, calcium (Ca) and phosphorus (P) of diets. The excretion of urinary nitrogen was decreased as the tannin level improved, thus lead the higher retention of N, the persistence of nitrogen of diet C was 23.61% (P﹤0.05), 12.57% and 15.88% (P﹥0.05) higher than diet A, B and D, the tannin contents of residue of tea-leaves had no significantly difference compared with PH of rumen fluid and total nitrogen concentration (P﹥0.05), while the content of ammonia and plasma urea nitrogen linear decreased as the tannin level improved, the NH3-N of died C and D was 50.36 (P﹥0.05) and 46.55 (P<0.05)percent of diet A, correspondingly, BUN was 68.04 and 59.99 percent(P﹤0.05). The results indicated that tea-leaf is high in protein and low in fiber and the tannins in it would prefer to reduce the degradation rate of feed CP in rumen, but did not affect the digestibility of the entire digestive tract, additionally, by reducing urinary N to improve nitrogen retention rate. Under the present experimental conditions, when tea-leaf take a percentage of 10 of diet and the content of TAE was 2.04 g·kg-1DM and CT was 1.53 g·kg-1DM had a better protection effect of feed protein, and had no significant effect of feed intake; high proportion of tea-leaf (15%) decreased feed intake of sheep.
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