旨在研究茶渣单宁含量对绵羊养分消化利用与氮代谢参数的影响.本研究分析了茶渣(RTL)的营养成分和单宁含量；用体外法测定6种配比茶渣/大豆粕混合料(0∶10、1∶9、2∶8、3∶7、4∶6、10∶0,其中茶渣缩合单宁(RTL-CT)含量依次为0.00、0.16、0.31、0.47、0.63和1.57 g·kg -1DM)的瘤胃液与瘤胃液+HCl-胃蛋白酶干物质(DM)与粗蛋白质(CP)降解率( rdDM、tdDM、rdCP、tdCP)；用4只安装永久性瘤胃瘘管的甘肃高山细毛羊羯羊(1岁半,体质量(29士2.55)kg),按4×4拉丁方方案进行试验,研究了饲粮RTL-CT水平(A、B、C、D分别为0.00、0.77、1.53、2.30 g·kg-1DM)对绵羊养分消化利用与氮代谢参数的影响,共4个15d的饲粮循环(预试期9d,收集期6 d).试验结果:(1)3个茶渣样的粗蛋白质(CP)、粗纤维(CF)、单宁(单宁酸等价,TAE)与CT含量范围分别为23.23％～28.11％、16.68％～17.84％、1.98％～2.10％和1.47％～1.57％.(2)茶渣/大豆粕混合料的rdDM、tdDM、rdCP、tdCP均随茶渣比例提高而线性下降,变化范围相应为61.39％～25.67％、79.61％～26.47％、60.76％～16.68％和84.85％～17.69％.(3)体内试验中,高比例茶渣影响采食量,饲粮D(P＜0.01)、C(P＞0.05)的DM与有机物质(OM)采食量低于A、B; RTL-CT对DM、OM、中性洗涤纤维、酸性洗涤纤维、氮、钙和磷的消化率无显著影响(P＞0.05)；但随RTL-CT水平提高尿氮排出量线性下降,导致氮存留率上升,C的氮存留率较A提高23.61％ (P＜0.05),B、D分别提高12.57％和15.88％ (P＞0.05)；随RTL-CT提高,瘤胃液pH、总氮浓度无显著变化(P＞0.05),而NH3-N与血浆尿素氮(BUN)含量线性下降,C、D的NH3-N分别是A的50.36％( P＞0.05)和46.55％ (P＜0.05),BUN相应为A的68.04％与59.99％(P＜0.05).可见,茶渣是高蛋白质、低纤维物质,单宁含量为中等的物质；本试验中,RTbCT降低了饲粮的体外瘤胃CP降解率,但未影响体内全消化道消化率,且通过减少尿N排出而提高了氮存留率；但高比例RTL-CT降低了绵羊采食量.显然,RTL-CT l.53 g·kg-1DM对饲粮蛋白质的保护效果较好,且对采食量无显著影响.%The present experiment was conducted to determine the effects of tannin content in residue of tea-leaves(RTL) on digestion and utilization of nutrients and metabolic parameters of nitrogen in sheep. The contents of nutrients and tannin in RTL were analysed; The in vitro de-gradability(rdDM,tdDM,rdCP.tdCP) of dry matter(DM) and crude protein(CP) of mixtures with six ratio of RTL to soybean meaKO: 10, 1:9, 2:8, 3:7, 4:6, 10:0 ), which levels of RTLcondensed tannin( RTL-CT) of the mixtures were 0. 00, 0.16, 0. 31, 0. 47, 0. 63, 1. 57 g ? Kg" ' DM, respectively, was measured by incubating in rumen fluid and rumen fluid + HCl-pepsin. To study the effects of RTL-CT contents on digestion and utilization of nutrients and metabolic profiles of nitrogen in sheep, four High Mountain Fine-wool wethers (one and a half years old and average live weight of (29 ±2. 55) kg) fitted with permanent rumen fistula and a 4X4 Latin square design with four cycles of diet each of 9 d for preliminary followed 6 d for sampling were used in this experiment. The contents of RTL-CT in diets were 0. 00(A) , 0. 77(B), 1. 53(C), 2. 30(D)g ? Kg "'DM . The results showed that: (1) the range of contents of CP, crude fiber (CF), TAE(tannic acid equivalent) and CT in three samples of TRL were 23. 23%-28. 11%, 16. 68%-17. 84%, 1.98%-2. 10%, 1.47%-1. 57%, respectively. (2) The degradabilities of DM and CP of the mixtures in rumen fluid and rumen fluid + HCl-pepsin (rdDM, tdDM, rdCP, td-CP) decreased linearly as the contents of RTL-CT , the range of change were 61. 39%-25. 67%, 79. 61%-26.47%, 60. 76%-16. 68%, 84. 85%-17. 69%, respectively. (3) In vivo, the intake of diet was affected by high-raito of RTL, compared with diet A and B, the intakes of DM and organic matter (OM) of diet C (P>0. 05) and diet D (P<0. 01) were lower; the digestibilities of DM, OM, calcium (Ca), phosphorus (P), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of diets were unaffected by the contents of RTL-CT(P>0. 05). But the excretions of urinary nitrogen were decreased linearly and retention of N increased as the RTL-CT level, the retention of nitrogen of diet B, C, D were raised by 12. 57% (P>0. 05), 23. 61%(P<0. 05) and 15. 88%(P>0. 05)than for diet A, respectively; there were no significant changes of the levels of Ph and total nitrogen of rumen fluid (P>0. 05) as the levels increasing of RTL-CT, while the contents of NH3-N and plasma urea nitrogen(BUN) linearly decreased, the levels of NH3-N and BUN of diet C and D were 50. 36 %(P>0. 05) , 46. 55%(P<0. 05)and 68. 04%, 59. 99%(P< 0. 05)lower than that of diet A, correspondingly. It follows that residue of tea-leaves were a matter with high-protein, low-fiber and middle content of tannin; under the condition of this experiment, the in vitro rdCP were decreased by RTL- CT, but the digestibilities of CP in total gastrointestinal tract were unaffected by levels of RTL-CT, and N retentions were increased owing to reducing of the excretion of N in urine as RTL-CT; yet high ratio of residue of tea-leaves in diet resulted in lowing of intake by sheep. Obviously, the protection effect of RTL-CT with 1. 53 g ? Kg" 'DM on protein was better, but no significant effect on the intake of diet.
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