【作者】 汪水平；

【导师】 龚月生； 王加启；

【作者基本信息】 西北农林科技大学 ， 动物营养与饲料科学， 2004， 硕士

【摘要】 本试验以平均体重为482.9 ±21.2kg、泌乳日龄为175 ±6d、同一日粮下产奶量为16.3 ±1.96kg的4头安装有永久性瘤胃、十二指肠近端、回肠末端T形瘘管的健康初产荷斯坦奶牛为研究对象，按照4×4拉丁方设计，研究了精粗比约为30:70的高低质粗料型日粮1（粗料仅由羊草干草组成）、30:70的混合型高青贮日粮2（粗料由苜蓿干草、羊草干草、玉米青贮组成）、50:50的精粗料比例相当的日粮3（粗料由苜蓿干草、羊草干草、玉米青贮组成）及65:35的高精料日粮4（粗料由苜蓿干草、羊草干草、玉米青贮组成）等四种日粮对奶牛瘤胃发酵、营养物质进食量及其全消化道消化率、行为学、生产性能和血液部分参数的影响。研究结果如下：1 不同日粮对奶牛瘤胃发酵的影响奶牛采食不同精粗比日粮，瘤胃平均pH值保持在6.26~6.56之间，各时间点值维持在6.0以上。随精粗比的提高，瘤胃平均pH值逐渐降低。其中，日粮4显著（p<0.05）低于其它日粮。另外，瘤胃平均pH值与日粮中性洗涤纤维和物理有效中性洗涤纤维含量、反刍和咀嚼时间均不相关。奶牛采食不同精粗比日粮，瘤胃氨氮平均浓度在8.58~18.57mg/dl之间。随日粮粗蛋白含量的提高，瘤胃氨氮平均浓度逐渐提高。其中，日粮3、4极显著（p<0.01）高于日粮1、2。奶牛采食不同精粗比日粮，瘤胃总挥发性脂肪酸、乙酸、丙酸、丁酸平均浓度分别在103.94~110.59、68.66~71.73、21.22~27.34mmol/m、10.86~14.37mmol/ml之间。随日粮精粗比的提高，瘤胃总挥发性脂肪酸、丙酸及丁酸平均浓度逐渐提高，而乙酸平均浓度逐渐降低。对于瘤胃总挥发性脂肪酸平均浓度，日粮1、2显著（p<0.05）低于日粮4；对于瘤胃乙酸平均浓度，各日粮间差异不显著（p>.05）；对于瘤胃丙酸平均浓度，日粮3、4间差异不显著（p>0.05），但和日粮1、2三者间有显著（p<0.05）差异；对于瘤胃丁酸平均浓度，日粮3、4显著（p<0.05）高于日粮1、2。瘤胃乙酸/丙酸平均值、（乙酸+丁酸）/丙酸平均值分别在2.53~3.42、3.05~3.94之间，均随日粮精粗比的提高而减小，且日粮3、4间差异不显著（p>0.05），但和日粮1、2三者间有极显著（p<0.01）差异。另外，瘤胃乙酸/丙酸平均值与中性洗涤纤维进食量/有机物进食量值呈强相关，线性回归方程为y=1.274+3.872x（R=0.884，p=0.000）；瘤胃乙酸/丙酸及（乙酸+丁酸）/丙酸平均值均与奶牛日反刍与咀嚼时间呈中等相关。奶牛采食不同精粗比日粮，瘤胃纤维素酶、木聚糖酶、内切葡聚糖酶、纤维二糖苷酶活性平均值在1.84~1.94、10.04~10.74、2.62~2.89、2.36~2.75IU之间，各日粮没有显著（p>0.05）差异。2 不同日粮对奶牛干物质、有机物、中性洗涤纤维、酸性洗涤纤维进食量及其全消化<WP=6>道消化率的影响采食日粮2的奶牛干物质进食量极显著（p<0.01）低于其它日粮，采食日粮1、4与日粮2、3的奶牛三者间有机物进食量差异极显著（p<0.01），而奶牛的中性洗涤纤维进食量和酸性洗涤纤维进食量各日粮间均有显著（p<0.05）差异。奶牛干物质进食量与日粮水分含量呈中等负相关，在水分含量为43.08%以下时奶牛干物质进食量不受影响。奶牛干物质进食量与日粮中性洗涤纤维含量（p=0.274）及精粗比（p=0.125）没有显著相关，但除日粮1外，其它三种日粮干物质进食量有随精粗比的提高和中性洗涤纤维含量的降低而提高的趋势。另外，本试验中，奶牛没有达到其最大的干物质进食量。奶牛有机物进食量大小取决于干物质进食量，而中性洗涤纤维进食量和酸性洗涤纤维进食量随日粮中羊草干草用量的增加而提高。 奶牛采食不同精粗比日粮，干物质、有机物、中性洗涤纤维、酸性洗涤纤维全消化道消化率差异均不显著（p>0.05），但干物质、有机物全消化道消化率有随日粮精粗比提高而提高的趋势，而中性洗涤纤维全消化道消化率的大小与日粮中玉米青贮含量的高低相一致。奶牛十二指肠前端内容物pH值平均为3.80，各日粮间没有显著（p>0.05）差异，但有随精粗比提高而降低的趋势。奶牛回肠末端内容物pH值平均为7.76，随精粗比的提高而降低，且日粮1、2与日粮3、4差异极显著（p<0.01）。3 不同日粮对奶牛行为学的影响奶牛日站立时间平均为13.6h，卧倒时间平均为10.4h，不受日粮显著（p>0.05）影响，但随日粮纤维水平的提高，站立时间延长，卧倒时间缩短。奶牛平均每食团反刍51.3次、49.1s，各日粮间差异不显著（p>0.05）。奶牛平均日排粪、排尿、饮水次数分别为15.7、7.7、6.2次，不受日粮显著（p>0.05）影响。奶牛日采食4~7h，日反刍7~10h，日咀嚼11~15h。除日粮2外，奶牛采食、反刍及咀嚼时间均随精粗比的提高而缩短。对于采食时间，日粮2极显著（p<0.01）长于其它日粮，而日粮4极显著（p<0.01）短于其它日粮；对于反刍时间，日粮4与日粮1、3差异极显著（p<0.01）；对于咀嚼时间，日粮4极显著（p<0.01）短于其它日粮。奶牛日单位干物质进食量采食、反刍、咀嚼时间为14.4~28.7min、25.3~34.7min、39.8~63.4min。日单位干物质进食量采食时间以日粮2最长（p<0.01）、日粮4最短（p<0.01）；日单位干物质进食量反刍时间随精粗比的提高而缩短，其中日粮4极显著（p<0.01）短于其它日粮；日单位干物质进食量?更多还原

【Abstract】 The effects of four rations with different concentrate-to-forage ratios on rumen fermentation, nutrients intake and their whole-tract digestibility, behavioral science, performance and several blood parameters in the jugular vein were evaluated using 4 primiparous Holstein cows that were surgically and permanently fitted ruminal, duodenal top, and ileum bottom T-shaped cannulas in a 4×4 Latin square design with four 21-d periods. The concentrate-to-forage ratios for the ration 1, 2, 3, and 4 were 30:70, 30:70, 50:50, 65:35, respectively. The forage of the ration 1 was only Chinese wildryegrass hay. The forage of the ration 2, 3, and 4 comprised of Chinese wildryegrass hay, alfalfa hay, and corn silage. Cows averaged of 482.9±21.2 (mean ±SD) kg body weight, 175 ±6d days in milk and 16.3 ±1.96kg milk yield at the beginning of the experiments.The results showed that: 1 Effect of dietary concentrate-to-forage ratio on rumen fermentation of lactating cows: When cows were fed different rations, the average ruminal pH values that declined in response to increased concentrate-to-forage ratio ranged between 6.26 and 6.56 and the single value of every time dot remained above 6.0. And the ration 4 was lower significantly (P<0.05) than other rations. The average ruminal pH values was not correlated to neutral detergent fiber and physical effective neutral detergent fiber content of the rations and the ruminating and chewing times of cows. When cows were fed different rations, the average ruminal concentrations of ammonia-N ranged between 8.58 and 18.57mg/dl and increased with increased content of dietary crude protein. And the ration 3 and 4 were higher significantly (P<0.01) than the ration 1 and 2. When cows were fed different rations, the average ruminal concentrations of total volatile <WP=9>fatty acids, acetate, propionate, and butyrate ranged between 103.94 and 110.59, 68.66 and 71.73, 21.22 and 27.34, 10.86 and 14.37mmol/ml, respectively. With increased concentrate-to-forage ratio, the average ruminal concentrations of total volatile fatty acids, propionate and butyrate increased, but that of acetate decreased. For the average ruminal concentrations of total volatile fatty acids, the ration 1 and 2 were lower significantly (P<0.05) than the ration 4; for that of acetate, no differences between the dietary treatments were significant (P>0.05); for that of propionate, no differences between the rations 3 and 4 were significant (P>0.05), but significant (P<0.05) differences existed among the ration 3, 4 and the ration 1 or 2; for that of butyrate, the ration 3 and 4 were higher significantly (P<0.01) than the ration 1 and 2. The average ruminal values of acetate/propionate and (acetate + butyrate)/propionate that bothl declined in response to increased concentrate-to-forage ratio ranged between 2.53 and 3.42, 3.05 and 3.94, respectively. And no differences between the rations 3 and 4 were significant (P>0.05), but significant (P<0.01) differences existed among the ration 3, 4 and the ration 1 or 2. The average ruminal values of acetate/propionate was highly and positively correlated with the ratio of neutral detergent fiber intake/organic matter intake, and the linearly regressive equality was y=1.274+3.872x(R=0.884, p=0.000). And the average ruminal values of acetate/propionate and (acetate + butyrate)/propionate were both medially and positively correlated with the ruminating and chewing times of cows. When cows were fed different rations, the average values of ruminal fil-papase, xylanase, CMCase, salicinase activity that were not affected by the dietary treatments significantly (P<0.01) ranged between 1.84 and 1.94IU, 10.04 and 10.74IU, 2.62 and 2.89IU, 2.36 and 2.75IU, respectively. 2 Effect of dietary concentrate-to-forage ratio on intake and whole-tract digestibility of dry matter, organic matter, neutral detergent fiber and acid detergent fiber of lactating cows: Dry matter intake when cows were fed the ration 2 was lower significantly (P<0.01) than that when cows were fed the ration 1, 3, and 4更多还原