高粗料日粮中添加脂肪对奶年血液代谢产物瘤胃发酵和干物质消化率影响的研究

对50头泌乳中期的奶牛进行为期6周的饲养试验，研究高粗料高脂肪日粮对奶牛血液代谢产物、瘤胃发酵和干物质消化率的影响。试验设有10个重复，每个重复5头奶牛，每头奶牛给定一种日粮。试验用日粮为：对照日粮（日粮1）和试验日粮（高粗料75％高脂肪7．5％，日粮2；高粗料，中等水平脂肪5．0％，日粮3；中等水平粗料65％，高水平脂肪，日粮4；中等水平粗料和脂肪，日粮5；或者对照日粮中含有50％粗料和2．0％脂肪）。这些日粮含氮量相同（CP17．7％）。粗饲料由20苜蓿干草、40％苜蓿半干青贮和40％青贮玉米组成。所用脂肪由80％瘤胃 保护脂肪和20％黄色油脂组成。试验结果表明：试验组和对照组的血糖浓度差异不显著；试验组的血浆非酯化脂肪酸（NEFA）高于对照组。而奶牛采食日粮的粗饲料和脂肪水平不同，其NEFA差异不显著；对照组、试验组与粗饲料和脂肪水平不同的日粮的瘤胃PH、瘤胃VFA浓度和干物质消化率差异不显著。

Effect of Feeding High Forage Diets with Supplemental Fat on Blood Metabolites,Rumen Fermentation and Dry Matter Digestibility in Dairy Cows

Fifty mid- lactation Holstein cows were used im a six - week feeding trialto study effects of high - forage, and high - fat diets on blood constituents, rumen fermentation and dry matter digestibility. Cows were divided into 10 replicates, each consisting of five cows. Each cow was assigned to a control(diet 1 ) or one of the four experimental diets (high - forage (75% ), high - far(7. 5% ) (diet 2); high - forage. medium - fat(5. 0% ) (diet 3); medium forage (65% ), high - fat (diet r); medium - forage, medium - fat(diet 5), or a control diet containing about 50% forage and 2% fat. All diets were isonitrogenous(17. 7% crude protein). The forage mixtrre consisted of 20% yellow grease. A non - significant difference was observed in concentrations Of blood glucose for cows on different experimental and control diets. plasma nonesterified fatty acids (NEFA) concentrations in theplasma of cows consuming diets with different forage and fat levels were not significant. Rumen PH, concentration of volatile fatty,acids (VFA) in rumen contents, and dry matter digestibility of contrtol and experimental diets, and diets with different levels of forage and supplemental fat did not differ significantly. (Asian Aus. J. Anim. SCI. 2000. VOL 13, No. 4: 451 - 456)