高粗料日粮中添加脂肪对奶牛血液代谢产物、瘤胃发酵和干物质消化率影响的研究

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

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间的瘤胃ＰＨ、瘤胃ＶＦＡ浓度和于物质消化率差异不显著。

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)