试验旨在研究牛至对荷斯坦奶牛瘤胃发酵、产奶量和乳脂肪酸组成的影响.试验选取4头瘤胃瘘管奶牛,采用4×4拉丁方设计,预饲期14 d,每期20 d,共4期.对照组:无牛至(OR)添加;牛至组:分为低、中、高3个添加组,每头牛日添加牛至量分别为250、500和750 g.结果表明:牛至组的瘤胃pH值、挥发性脂肪酸(VFA)浓度和微生物蛋白质合成量与对照组间均无显著性差异(P>0.05),每单位干物质采食量(DMI)的CH4产量随着牛至添加量的增加而有所降低;瘤胃细菌、产甲烷菌和真菌群体的比例不受OR添加的影响;牛至的添加对饲粮中营养素的表观消化率没有影响,但牛至组的中性洗涤纤维消化率较对照组明显降低;与对照组相比,牛至组的尿素氮占总排泄尿氮的比例有降低趋势,尿素氮损失和粪便气味组间并没有明显差别;对照组与牛至组间的产奶量也无明显差异;饲料效率随着牛至添加量增加而线性增加;牛至添加对牛奶组成未见明显的影响.说明饲粮中添加牛至减少了DMI摄入量,提高了饲料效率.%In order to investigate the effects of oregano on rumen fermentation,production parameters and milk fat composition in lactating Holstein,four cows with rumen fistulae were selected and a 4×4 Latin square design was used. The pre-feeding period was 14 d,20 d for each feeding period of total four. The four groups were control group,oregano group Ⅰ (250 g/d),oregano group Ⅱ(500 g/d),oregano group Ⅲ(750 g/d).Compared with the control group,the rumen pH,VFA concentration and the microbial protein yield in the oregano groups had no significant difference(P > 0.05),so did the proportion of rumen bacteria,methanogens and fungal population,but the NH3 concentration decreased,the CH4 yield decreased linearly; compared with the control group, the apparent digestibilities of nutrients in the oregano groups had no significant difference(P>0.05),but the digestibilities of NDF in the oregano groups decreased obviously; besides,compared with the control group,the total excretion of urea nitrogen in the oregano groups were reduced,but no significant affect on the loss of urea nitrogen and fecal odor were found. The milk yield and the milk composition were not affected by the treatments,but the feed efficiency increased linearly with the increase of oregano. It could be concluded that supplementary oregano in the lactating cow diet might reduce the DMI and increase feed ef-ficiency,but had no significant affects on milk yield and milk composition.
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