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
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?
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
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
引文
[1] 李易方.奶业结构调整聚焦[J].中国奶牛,2001,(4):5~7
[2] 王根林.我国奶业迫切需要解决的几个问题——亦谈加入WTO后我国奶业面临的机遇与挑战[J].畜牧与兽医,2003,34(5):1~3
[3] D. L. 柏奇,F. N. 狄更生,H. A. 特克等著. 乳牛学[M]. 金国粹,邱怀,冀一伦等译. 北京:农业出版社,1996:1~4
[4] 周鼎年.发展奶牛业生产是改善我国食物结构的重大措施[J].中国奶牛,1998,(6):56~58
[5] Byerly T. C. Science, 1977, 195: 450
[6] 韩高举.我国奶牛业应该有一个更快发展[J].中国奶牛,1998,(2):5~7
[7] 周俊玲.中国乳品消费研究[J].中国奶牛,2001,(2):18~22
[8] 韩刚.浅谈牛奶的营养价值[J].中国奶牛,1997,(3):46~48
[9] Patton R. S著,朱钦龙译.奶牛饲料中的可溶性碳水化合物[J]. 四川奶牛,1999,(2):21~22
[10] 孟庆翔.反刍动物瘤胃酸中毒研究的最新进展[C].面对21世纪动物科学与动物医学国际研讨会文集,中国畜牧兽医学会,2000:73
[11] 卢德勋.乳牛八大营养工程技术[J].饲料广角,2001,(9):1~6
[12] 高民,卢德勋.可发酵碳水化合物对纤维物质降解动力学影响的研究[J].内蒙古畜牧科学,1997,(1):5~8,22
[13] 王中华.反刍动物挥发性脂肪酸中间代谢[J].草食家畜,1995,(2):23~30
[14] 孙海洲,卢德勋,斯琴.生长肥育羊葡萄糖营养整体优化规律的研究[J].内蒙古畜牧科学,1999,(1):25~29
[15] 李胜利.过瘤胃淀粉在奶牛营养中的作用[J].中国奶牛,2000,(4):22~24
[16] 张健中.反刍动物对淀粉的消化和利用[J].草食家畜,1996,12(4):31~35
[17] 谭支良,卢德勋,胡明等.绵羊日粮不同碳水化合物比例对纤维物质在消化道不同部位流通量和消化率的影响[J].动物营养学报,1999,11(4):29~38
[18] 谭支良.绵羊日粮中不同碳水化合物和氮源比例对纤维物质消化动力学的影响及其组合效应评估模型[D].呼和浩特:内蒙古农业大学,1998
[19] 熊易强.反刍动物消化动态学-粗饲料消化方面的研究进展[J].草食家畜,1984,(5)
[20] 杨凤主编.动物营养学[M].北京:农业出版社,1993
[21] 熊本海.生长肥育羊瘤胃内VFA产生、吸收规律及模型参数研究[D].北京:中国农业科学院研究生院,1998
[22] 冯仰廉.碳水化合物营养(参考教材)[C].北京农业大学,内部教材,1991
[23] 张建中.肉牛小肠碳水化合物的消化及其对能量转化的调控研究[D].北京:中国农业
大学,1997
[24] 李福昌.肉牛小肠玉米淀粉的消化率及其对能量转化的调控[D].北京:中国农业大学,1998
[25] 李胜利.肉牛VFA能量转化效率及营养调控的研究[D].北京:中国农业大学,1996
[26] 李建国.肉牛小肠蛋白质、淀粉和脂肪对能量转化的调控研究[D].北京:中国农业大学,1997
[27] 刘丽英主编.饲料分析及饲料质量检测技术[M].北京:中国农业大学出版社,2003
[28] 冯宗慈,高民.通过比色法测定瘤胃液氨氮含量方法的改进[J].内蒙古畜牧科学,1993,4:40~41
[29] 李振甲主编.实用放射免疫学[M].北京:科学技术文献出版社,1985
[30] 王明运主编.实用临床生物化学[M].北京:科学技术文献出版社,1989
[31] 李振甲主编.激素的放射免疫分析[M].北京:科学技术文献出版社,1989
[32] 杨纲主编.内分泌学[M].武汉:武汉出版社,1998
[33] 贵州农学院主编.生物统计附试验设计(第二版)[M].北京:农业出版社,1986
[34] 南京农业大学主编.家畜生理学(第三版)[M].北京:中国农业出版社,1997年
[35] M. J. 斯文森主编.家畜生理学[M].华北农业大学等译校.北京:科学出版社,1978
[36] 汪玉松、邹思湘主编.乳生物化学[M].长春:吉林大学出版社,1995
[37] 梁学武著,邹霞青主审.现代奶牛生产[M].北京:中国农业出版社,2002
[38] 邱怀主编.现代乳牛学[M].北京:中国农业出版社,2002年
[39] Shaver R. D., A. J. Nytes, L. D. Satter, et al. Influence of amount of feed intake and forage physical form on digestion and passage of prebloom alfalfa hay in dairy cows [J]. J. Dairy Sci., 1986, 69: 1545~1559
[40] Clark P. W., L. E. Armentano. Effectiveness of neutral detergent fiber in whole cottonseed and dried distillers grains compared with alfalfa haylage [J]. J. Dairy Sci., 1993, 76: 2644~2650
[41] Depies K. K., L. E. Armentano. Partial replacement of alfalfa fiber with fiber from ground corn cobs or wheat middlings [J]. J. Dairy Sci., 1995, 78: 1328~1335
[42] Nutrient requirements of dairy cattle (7th). National Academy Press, Washington, D. C.
[43] Nocek J. E. Bovine acidosis: implications on lameness [J]. J. Dairy Sci., 1997, 80: 1005~1028
[44] Rode L. M., D. C. Weakley, D. Satter. Effect of forage amount and particle size in diets of lactating dairy cows on site of digestion and microbial protein synthesis [J]. J. Anim. Sci., 1985, 65: 101~111
[45] Nelson M. L., J. W. Finley. Effect of soft white wheat addition to alfalfa-grass forage an heifer gain, diet digestibility and in vitro digestion kinetics [J]. J. Anim. Feed Sci. Technol,
1989, 24: 141~150
[46] Stokes S. R., W. H. Hoover, T. K. Miller, et al. Ruminal digestion and microbial utilization of diets varying in type of carbohydrate and protein [J]. J. Dairy Sci., 1991, 74: 871~881
[47] Flachowsky G., M. Schneider. Influence of various straw to concentrate ratios in sacco dry matter degradability, feed intake and apparent digestibility in ruminants [J]. Anim. Feed Sci. Technol., 1992, 38: 199~217
[48] Castrillo C., M. Fondevila, J. A. Guada, et al. Effect of ammonia treatment and carbohydrate supplementation on the intake and digestibility of barley straw diets by sheep [J]. Anim. Feed Sci. Technol., 1995, 51: 73~90
[49] MacGrgeor C. A., M. R. Stokes, W. H. Hoover, et al. Effect of dietary concentration of total nonstructural carbohydrate of dairy cows [J]. J. Dairy Sci., 1983, 66: 39~50
[50] Brink D. R., R. T. Steele. Site and extent of starch and neutral detergent fiber digestion as affected by some of calcium and level of corn [J]. J. Anim. Sci., 1985, 60: 1330~1337
[51] Khalili H., P. Huhtanen. Sucrose Supplements. In cattle given grass silage based diet. 2. Digestion of cell wall carbohydrate [J]. Anim. Feed Sci. Technol., 1991, 33: 363~373
[52] Doyle P. T., H. Dove, M. Freer, et al. Effects of a concentrate supplement on the intake and digestion of a low quality forage by lambs [J]. J. Agric. Sci., 1988, 111: 503~511
[53] Ortigues I., T. Smith, J. D. Oldham, et al. Nutrient supply and growth of cattle offered straw-based diet [J]. Brit. J. Nutr., 1989, 62: 601~619
[54] Brown W. F., D. D. Johnson. Effects of energy and protein supplementation of ammoniated tropical grass hay on the growth and carcass characteristics of cull cows [J]. J. Anim. Sci., 1991, 69: 348~357
[55] Miller T. P., W. B. Tucker, M. Lema, et al. Influence of dietary buffer value index on the ruminal milieu of lactating dairy cows fed sorghum silage and grain [J]. J. Dairy Sci., 1993, 76: 3571
[56] Hale W. H. Influence of processing on the utililization of grains (starch) by ruminants [J]. J. Anim. Sci., 1973, 37: 1075
[57] Del Valle J., Park J., China T., et al. Cellular mechanisms of somatostatin action in the gut [J]. Metabolism, 1990, 9: 134~137
[58] Waldo D. R. Extent and partition of cereal grain starch digestion in ruminants [J]. J. Anim. Sci., 1973, 37: 1062
[59] Teeri T. T. Crystalline cellulose degradation: new insight into the function of cellobiohydrolases [J]. Trends Biotechnol, 1997, 15: 160~167
[60] Nordin M. Digestibility studies with cows given shole and rolled cereal grains [J]. Anim.
Prod., 1976, 23: 305
[61] Van Eenaene C. Effects of dietaty carbohydrate composition on rumen fermentation plass hormone and metabolites in growing-fattening bulls [J]. Anim. Prod, 1990, 50: 409
[62] Seal C. J., Parker D. S. Net absorption of low molecular weight peptides by the mesenteric and portal drained viscera of steers [A]. Proceedings of the Nutrition Society, 1993, 52: 190
[63] Brockman R. P. Roles of glucagon and insulin in the regulation of metabolism in ruminants: A review [J]. Can. Vet. J., 1978, 19:55
[64] Kennedy D. W.,et al. Effects of starch on ruminal fermentation and detergent f [J].1992
[65] Gray G. M. Starch digestion and absorption in nonruminants [J]. J. Nutr., 1992, 122: 172
[66] Phillips W. A., Webb K. E., Fontenot J. P. In vitro absorption of amino acids by the small intestine of sheep [J]. Journal of Animal Science, 1976, 42: 201~207
[67] Peters J. P., Shen R. Y. W., Robinson. J. A., et al. Disappearance and passage of propionic acid from the rumen of the beefs steer [ J]. Journal of Animal Science, 1990, 68: 3337~3349
[68] Leng R. A. The effect on growth of supplying glucose continuously into the duodenum of lambw on low-protein diets [J]. Proceedings Australian Society of Anim. Prod, 1977, 12: 134
[69] Pennington R. J. The metabolism of short-chain fatty acids in the sheep.1.Fatty acid utilization and ketone body production by the rumen epithelium and other tissues [J]. Biochemical Journal, 1952, 51: 251~258
[70] Hanigan M. D., J. France, D. Wray-Cahen, et al. The effect of EGF on the enterocyte brush border [J]. Gastroenterology, 1991, 100: 827 (Abstr.)
[71] Ketelaars J. J. M. H., B. J. Tolkamp. Oxygen efficiency and the control of energy flow in animals and humans [J]. J. Anim Sci., 1996, 74: 3036~3051
[72] Spicer L. A. Ruminal and postruminal utilization of mitrogen and starch from sorghum grain.corn and braley based diets by beefs steers [J]. J. Anim. Sci., 1986, 62: 521
[73] Macleod N. A. Introgastricinfusion of nutrients in cattle [J]. Brit. J. Nutr., 1982, 47: 547
[74] Owens F. N. Limits to starch digestion im the ruminamt small intestine [J]. J. Anim. Sci., 1986, 63: 1634
[75] Herrera-Saldana R. R, Gome-Alarcon M. Torabi, J. T. Huber. Influence of synchronizing protein and starch degradation in the rumen on nutrient utilization and microbial protein synthesis [J]. J. Dairy Sci., 1990, 73: 2386
[76] Huntington G. B. Starch utilization by ruminants: from basics to the bunk [J]. J. Anim. Sci.., 1997, 75: 852
[77] Karr P. M. Starch disappearances from different segments of the digestive tracr of steers [J]. J. Anim. Sci., 1966, 25: 652
[78] Little C. O. Postruminal digestion of corn starch in steers [J]. J. Anim. Sci., 1968, 27: 790
[79] Mayes R. W. The utilization of gelled maize starch in the small intestine of sheep [J]. Brit. J. Nutr., 1974, 32: 143
[80] Johnson R. R. Influence of carbohydrate solubility on momprotein nitrogen utilization in the ruminant [J]. J. Anim. Sci., 1976,64 (suppl.): 86
[81] Kreikemeier K. K. Abomasal glucose: maize starch and maize dextrin infusion in cattle-small-intestinal disappearance: net portal glucose flux and ileal oligosaccharide flow [J]. Brit. J. Nutr., 1995, 73: 763~772
[82] Orskov E. R. Efficiency of utilization of VFAs for maimtenance and energy retention by sheep [J]. Br. J. Nutr., 1979, 41: 541
[83] Reynolds C. K., Tyrrell H. F., Reynolds P. J. Effects of diet forage-to-concentrate ratio and intake on net visceral metabolism of VFA in growing beefs heifers [J]. Journal of Dairy Science, 1993, 76 (Supp1.1): 283
[84] Mertens D. R. Creating a system for meeting the fiber requirements of dairy cows [J]. J. Dairy Sci., 1997, 80: 1463~1481
[85] Sievert S. J., R. D. Shaver. Effect of nonfiber carbohydrate level and aspergillus oryzae fermentation extract on intake, digestion, and milk production in lactating dairy cows [J]. J. Anim. Sci., 1993, 71: 1032~1040
[86] Sutton J. D. Altering milk composition by feeding [J]. J. Dairy Sci., 1989, 72: 2801~ 2814
[87] Batajoo K. K., R. D. Shaver. Impact of nonfiber carbohydrate on intake, digestion, and milk production by dairy cows [J]. J. Dairy Sci., 1994, 77: 1580~1587
[88] Nocek J. E., J. B. Russell. Protein and energy as an integrated system. Relationship of ruminal protein and carbohydrate availability to microbial synthesis and milk production [J]. J. Dairy Sci., 1988, 71: 2070~2107
[89] Hoover W. H., S. R. Stokes. Balancing carbohydrates and protein for optimum rumen microbial yield [J]. J. Dairy Sci., 1991, 74: 3630~3644
[90] Minor D. J., S. L. Trower, B. D. Strang, et al. Effects of nonfiber carbohydrate and niacinon on periparturient metabolic status and lactation of daire cows [J]. J. Dairy Sci., 1988, 81: 189~200
[91] Herrera-Saldana R. R., J. T. Huber. Influence of lactating cows [J]. J. Dairy Sci., 1989, 72: 1477~1483
[92] McCarthy R. D., Jr., T. H. Klusmeyer, et al. Effects of source of protein and carbohydrate on ruminal fermentation and passage of nutrients to the small intestine of lactating cows [J]. J. Dairy Sci., 1989, 72: 2002~2016
[93] Moore J. A., M. H. Poore, T. P. Eck, et al. Sorghum grain processing and buffer addition for eary lactation cows [J]. J. Dairy Sci., 1992, 75: 3465~3472
[94] Knowlton K. F., M. S. Allen, P. S. Erickson. Lasalocid and particle size of corn grain for dairy cows in early lactation. 1. Effect on performance, sermum metabolites, and nutrient digestility [J]. J. Dairy Sci., 1996, 79: 557~564
[95] Wilkerson V. A., B. P. Glenn. Energy balance in eary lactation Holstein cow fed corn grains harvested and processed differently [J]. J. Dairy Sci., 1977, 80: 2487~2496
[96] Lykos T., G. A. Varga, D. Casper. Varying degradation rates of total nonstructural carbohydrates: Effects on ruminal fermentation,blood metabolites,and milk production and composition in high producing Holstein cows [J]. J. Dairy Sci., 1997, 80: 3341~3355
[97] Aldrich M. M., L. D. Muller, G. A. Varga, et al. Nonstructural carbohydrate and protein effects on rumen fermentation, nutrient flow, and performance of dairy cows [J]. J. Dairy Sci., 1993, 76: 1091~1105
[98] Clark J. H., K. E. Harshbarger. High moisture corn versus dry corn in combination with either corn silage or hay for lactating cows [J]. J. Dairy Sci., 1972, 55: 1474~1480
[99] Oliveira J. S., J.T. Huber, D. Ben-Ghedalia, et al. Influence of sorghum grain processing on performance of lactaing dairy cows [J]. J. Dairy Sci., 1993, 76: 575~581
[100] Oliveira J. S., J. T. Huber, J. M. Simas, et al. Effect of sorghum grain processing on site and extract of digestion of starch in lactating dairy cows [J]. J. Dairy Sci., 1995, 78: 1318~1327
[101] Varga G. A., P. Kononoff. Dairy rationing using structural and nonstructural carbohydrates: from theory AZ to paractice [C]. Proc. Southwest Nutr. Cont. Phoeinx: 77~90
[102] Mertens D. R. Regulation of forage intake. In: Forage Quality,evaluation and Utilization. G. C. Fahey, ed. Am. Soc. Agron., Crop Sci. Soc Amer., Soil Sci. Soc. Amer. Madison, WI. pp. 450– 493, 1994
[103] Colenbrander V. F., C. H. Noller, R. J. Grant. Effect of fiber content and particle size of alfalfa silage on performance and chewing behaviour [J]. J. Dairy Sci., 1991, 74: 2681~2690
[104] Cummins K. A. Effect of dietary acid detergent fiber on responses to high environmental temperature [J]. J. Dairy Sci., 1992, 75: 1465~1471
[105] Bal M. A., T. G. Coors, R. D. Shaver. Impact of the maturity of corn for use as silage in the diets of dairy cows on intake, digestion and milk production [J]. J. Dairy Sci., 1997,80: 2497~2503
[106] Wangsness P. J., L. E. Chase, A. D. Peterson, et al. System for monitoring feeding behavior of sheep [J]. J. Anim. Sci., 1976, 42: 1544~1549
[107] Broderick G. A., Kang J. H. Automated simultaneous determination of ammonia and
total amino acids in ruminal fluid and in vitro media [J]. J. Dairy Sci., 1980, 63: 64
[108] Chaney A. L., Marbach, E. P. Modified reagents for determination of urea and ammonia [J]. Clin Chem., 1962, 8: 130
[109] Van Houtert M. F. J. The production and metabolism of volatile fatty acids by ruminants fed roughages: A review [J]. Anim. Feed Sci. Technol., 1993, 43: 189~225
[110] Kononoff P. J., A. J. Heinrichs. The Effect of corn silage particle size and cottonseed hulls on cows in early lactation [J]. J. Dairy Sci., 2003, 86: 2438~2451
[111] Yang W. Z., K. A. Beauchemin, L. M. Rode. Effects of grain processing, forage to concentrate ratio, and forage particle size on rumen pH and digestion by dairy cows [J]. J. Dairy Sci., 2001, 84: 2203~2216
[112] Murphy M., M. Akerlind, K.Holtenins. Rumen Fermentation in lactating cows. Selected for fat content fed two forage to concentrate ratio with or silage [J]. J. Dairy Sci., 2000, 83: 756~764
[113] Calberry J. M., J. C. Plaizier, M. S. Einarson, et al. Effects of replacing chopped alfalfa hay with alfalfa silage in a total mixed ration on production and rumen conditions of lactating dairy cows [J]. J. Dairy Sci., 2003, 86: 2420~2428
[114] Onetti S. G., R. D. Shaver. The effect of reducing alfalfa haylage particle size on cows in early lactation [J]. J. Dairy Sci., 2003, 86: 2949~2957
[115] Beauchemin K. A. Effects of dietary neutral detergent fiber concentration and alfalfa hay quality on chewing, rumen function, and milk production of dairy cows [J]. J. Dairy Sci., 1991, 74: 3140~3151
[116] Pitt R. E., J. S. Van Kessel, D.G. Fox, et al. Prediction of ruminal volatile fatty acids and pH within the Net Carbohydrate and Protein System [J]. J. Anim. Sci., 1996, 74: 226~244
[117] Nocek, J. E., S. Tamminga. Site of digestion of starchin the gastrointestinal tract of dairy cows and its effect on milkyield and composition [J]. J. Dairy Sci., 1991, 74: 3598~3629
[118] Demeyer D. I. Rumen microbes and digestion of plant cell walls [J]. Agric. Environ., 1981, 6: 295~337
[119] Contreras P. A., C. Larrain, F. Wittwer, et al. Effect of dietary sodium bicarbonate and sodium bicarbonate plus magnesium-oxide on rumen fluid and milk yield in cows [J]. Arch. Med. Vet., 1992, 24: 131~139
[120] Yang C. M. J., G. A. Varga. The effects of continuousruminal dosing with dioctyl sodium sulfosuccinate on ruminal andmetabolic characteristics of lactating Holstein cows [J]. Br. J. Nutr., 1993, 69: 397~408
[121] Drackey D. J., A. D. Beaulieu, J. P. Elliott. Responses of milk fat composition to dietary
fat or nonstructural in Holstein and Jersey cows [J]. J. Dairy Sci., 2001, 84: 1231~1237
[122] Woodford J. A., N. A. Jorgensen, G. P. Barrington. Impact of dietary fiber on performance of lactating dairy cows [J]. J. Dairy Sci., 1986, 69: 1035~1045
[123] Van Soest P. J. pp. 334~336 In Nutritional Ecology of the Ruminant [M]. Cornell University Press, Ithaca, New York, 1994
[124] Ash R. W., A. Dobson. The effect of absorption on the acidity of rumen content [J]. J. Physiol., 1963, 147: 58
[125] Weimer P. J. Why don’t ruminal bacteria digest cellulose faster? [J]. J. Dairy Sci., 1996, 79: 1496~1502
[126] Grant R. J. Influence of corn and sorghum starch on the in vitro kinetics of forage fiber digestion [J]. J. Dairy Sci., 1994, 77: 1563~1569
[127] Hoover W.H. Chemical factors involved in ruminal fiber digestion [J]. J. Dairy Sci., 1986, 69: 2755~2766
[128] Mould F. L., E.R.фrskov. Manipulation of rumen fluid pH and its influence on cellulolysis in sacco,dry matter degradation and the rumen microflora of sheep offered either hay or concentrate [J]. Anim. Feed Sci. Technol., 1983/1984, 10: 1~14
[129] Mould F. L., E. R.фrskov. Associative effects of mixed feeds: Ⅰ. Manipulation of type and level of supplementation and the influence of rumen fluid pH on cellulolysis in vivo and dry matter digestion of various roughages [J]. Anim. Feed Sci. Technol., 1983/1984, 10: 15~30
[130] Russell J. B., D. B. Wilson. Why are ruminal cellulolytic bacteria unable to digest cellulose at low pH? [M]. J. Dairy Sci., 1996, 79: 1503~1509
[131] Russell J. B., J. D. O’Connor, D. G. Fox, et al. A net carbohydrate and protein system for evaluating cattle diets:Ⅰ.Ruminal fermentation [J]. J.Anim.Sci., 1992, 79: 1503~1509
[132] Sniffen C. J., J. D. O’Connor, P. J. Van Soest, et al. A net carbohydrate and protein system evaluating cattle diets:Ⅱ. Carbohydrate and protein availability [J]. J. Anim. Sci., 1992, 70: 3562~3577
[133] Allen M. S. Physical constrains on voluntary intake of forages by ruminants [J]. J. Anim. Sci., 1996, 74: 3063~3075
[134] Illius A. W., N. S. Jessop. Metabolic constraints on voluntary intake in ruminants [J]. J. Anim Sci., 1996, 74: 3052~3062
[135] Baumont R. Palatability and feeding behavior in ruminants [J]. A review Ann. Zootech, 1996, 45: 385~ 400
[136] Chase L. E. Effect of high moisture feeds on feed intake and milk production in dairy cattle [C]. Proc., Cornell Nutr. Conf. Feed Manu., 1979: 52~ 56
[137] Kellems R. O., R. Jones, D. Andrus, et al. Effect of moisture in total mixed rations on feed consumption and milk production and composition in Holstein cows [J]. J. Dairy Sci., 1991, 74: 929~ 932
[138] Holter J. B., W. E. Urban. Water partitioning and intake predicition in dry and lactating Holstein cows [J]. J. Dairy Sci., 1992, 75: 1472~ 1479
[139] Dado, R. G., M. S. Allen. Intake limitations, feeding behavior and rumen function of cows challenged with rumen fill from dietary fiber of inert bulk [J]. J. Dairy Sci., 1995, 78: 118~ 133
[140] Allen M. S. Effects of diet on short-term regulation of feed intake by lactating dairy cows [J]. J. Dairy Sci., 2000, 83: 1598~1624.
[141] Llamas-Lamas G., D. K. Combs. Effect of forage to concentrate ratio and intake level on utilization of early vegetative alfalfa silage by dairy cows [J]. J. Dairy Sci., 1991, 74: 526~ 536
[142] Johnson T. R., D. K. Combs. Effects of inert rumen bulk on dry matter intake in early and midlactation cows fed diets differing in forage content [J]. J. Dairy Sci., 1992, 75: 508~ 519
[143] Weiss W. P., W. L. Shockey. Value of orchardgrass and alfalfa silages fed with varying amounts of concentrate to dairy cows [J]. J. Dairy Sci., 1991, 74: 1933~1943.
[144] Sarwar M., J. L. Firkins, M. L. Eastridge. Effects of varying forage and concentrate carbohydrate on nutrients digestibilities and milk production by dairy cows [J]. J. Dairy Sci., 1992, 66: 811~820
[145] Voelker J. A., G. M. Burato, M. S. Allen. Effects of pretrial milk yield on responses of feed intake,digestion, and production to dietary forage concentation [J]. J. Dairy Sci., 2002, 85: 2650~2661
[146] Wheeler W. E., C. H. Noller, C. E. Coppock. Effect of forage-to-concentrate ratio in complete feeds and feed intake on digestion of starch by dairy cows [J]. J. Dairy Sci., 1975, 58: 1902~1906
[147] Alhadhrami G. J., T. Huber. Effects of alfafa hay of varying fiber fed at 35 or 50% of diet on lactation and nutrient utilization by dairy cows [J]. J. Dairy Sci., 1992, 75: 3091~3099
[148] Khorasani G. R., E. K. Okine, J. J. Kennelly. Effects of forage source and amount of concentrate on rumen and intestinal digestion of nutrients in late-lactation cows [J]. J. Dairy Sci., 2001, 84: 1156~1165
[149] Krause K. M., D. K. Combs, K. A. Beauchemin. Effects of forage particle size and grain fermentability in midlactation cows. I. Milk production and diet digestibility [J]. J. Dairy Sci., 2002, 85: 1936~1946
[150] Knowlton K. F., B. P. Glenn, R. A. Erdman. Performance, ruminal fermentation, and site of starch digestion in early lactation, cows fed corn grain harvested and processed differently [J]. J. Dairy Sci., 1998, 81: 1972~1984
[151] Ying Y., M. S. Allen, M. J. VandeHaar, et al. Effects of fineness of grinding and conservation method of corn grain on ruminal and whole tract digestibility and ruminal microbial protein production of Holstein cows in early lactation [J]. J. Dairy Sci., 1998, 81 (Suppl. 1): 1330 (Abstr.)
[152] Stensig T., P. H. Robinson. Digestion and passage kinetics of forage fiber in dairy cows as affected by fiber-concentrate in the diet [J]. J. Dairy Sci., 1997: 1339~1352
[153] Ash R. W. Stimuli influencing the secretion of acid by the abomasums of sheep [J]. J. Physiol., 1961, 157: 185~207
[154] McCullough M. E. Optimum Feeding of Dairy Animals [M]. Univ. Press, Athens, GA., 1973
[155] Miller W. J., G. D. O’Dell. Nutritional problems of using maximum forage or maximum concentrates in dairy rations [J]. J. Dairy Sci., 1969, 52: 1144
[156] Mertens D. R. Factors influencing feed intake in lactating cows: from theory to application using neutral detergent fiber. Page 1 in Georgia Nutr. Conf., Univ. Georgia, Athens., 1985
[157] Mertens D. R. Predicting intake and digestibility using mathematical models of ruminal function [J]. J. Anim. Sci., 1987, 64: 1548
[158] Mertens D. R. Nonstructural and structural carbohydrates. Page 219 in Large Dairy Herd Management. Am. Dairy Sci. Assoc., Champaign, IL., 1992
[159] Welch J. G., A. M. Smith, K. S. Gobson. Rumination time in four breeds of dairy cattle [J]. J. Dairy Sci., 1970, 53: 89.
[160] Bae D. H., J. G. Welch, B. E. Gilman. Mastication and rumination in relation to body size of cattle [J]. J. Dairy Sci., 1983, 66: 137
[161] Sauvant D., J. P. Dulphy, B. Michalet-Doreau. The concept of fibrosity index of ruminant feeds. Int. Natl. Rech. Agron. Prod. Anim., 1990, 3: 309
[162] Jaster E. H., M. R. Murphy. Effects of varying particle size of forage on digestion and chewing behavior of dairy heifers [J]. J. Dairy Sci., 1983, 66: 802
[163] Oba M., M. S. Allen. Effect of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent: 2.Chewing acivities [J]. J. Dairy Sci., 2000, 83: 1342~1349
[164] Norgaard P. Physical structure of feeds for dairy cows. Page 85 in New Developments and Future Perspectives in Research on Rumen Function. A. Neimann-Sorensen, ed. Comm.
Eur. Commun., Luxembourg, Luxembourg, 1986
[165] Sudweeks E. M., L. O. Ely, D. R. Mertens, et al. Assessing minimum amounts and form of roughages in ruminant diets: Roughage value index system [J]. J. Anim. Sci., 1981, 53: 1406~1411
[166] Beauchemin K. A., B. I. Farr, L. M. Rode, et al. Effects of alfalfa silage chop length and supplementary long hay on chewing and milk production of dairy cows [J]. J. Dairy Sci., 1994, 77: 1326
[167] Hansen W. P., D. E. Otterby, J. G. Linn, et al. Influence of forage type, ratio of forage to concentrate, and methionine hydroxy analog on performance of dairy cows [J]. J. Dairy Sci., 1991, 74: 1361~1369
[168] Powell E. B. Some relations of the roughage intake to compositionof milk [J]. J. Dairy Sci., 1939, 22: 452.
[169] Emery R. S., L. D. Brown. Effect of feeding sodium and potassium bicarbonate on milk fat, rumen pH, and volatile fatty acid production [J]. J. Dairy Sci., 1961, 44: 1899~ 1902
[170] Tyznick W., N. N. Allen. The relation of roughage intake to the fat content of the milk and the level of fatty acids in the rumen [J]. J. Dairy Sci., 1951, 34: 493
[171] Emery R. S., L. D. Brown, J. W. Thomas. Effect of sodium bicarbonate and calcium carbonates on milk production and composition of milk, blood, and rumen contents of cows fed grain ad libitum with restricted roughage [J]. J. Dairy Sci., 1964, 47: 1325
[172] Beauchemin K. A., L. M. Rode. Minimum versus optimum concentrations of fiber in dairy cow diets based on barley silage and concentrates of barley or corn [J]. J. Dairy Sci., 1997, 80: 1629~1639
[173] Baldwin R. L., H. J. Lin, W. Cheng, et al. Enzyme and metabolite levels in mammary and abdominal adipose tissue of lactating dairy cows [J]. J. Dairy Sci., 1969, 52: 183~191
[174] Mackle T. R., D. A. Dwyer, K. L. Ingvartsen, et al. Effects ofinsulin and amino acids on milk protein concentration and yield from dairy cows [J]. J. Dairy Sci., 1999, 82: 1512~1524