本试验旨在研究饲喂包被尿素对奶牛泌乳性能及血浆生化指标的影响。选用24头荷斯坦泌乳牛，随机分为3组，分别饲喂含有豆粕（豆粕组）、聚氨酯包被尿素（包被尿素组）、饲料级尿素（尿素组）的等氮饲粮，粗蛋白质水平为17%。结果表明，与尿素组相比，包被尿素组和豆粕组奶牛干物质采食量提高了12.8%和12.6%，差异显著（P=0.02）；产乳量由32.48 kg/d提高到34.48和34.53 kg/d，差异不显著（P>0.05），乳蛋白质产量有增加的趋势（P=0.06）。尿素组奶牛乳蛋白质率显著低于其他2组（P=0.04），而乳尿素氮浓度显著高于其他2组（P=0.03）。与尿素组相比，包被尿素组和豆粕组奶牛血浆中尿素氮含量由18.7 mg/dL降低到16.7和16.4 mg/dL（P=0.05）。乳尿素氮含量和血浆尿素氮含量存在正相关（R2=0.85）。由此得出，聚氨酯包被尿素可以部分替代饲粮中的豆粕，而不会对奶牛的泌乳性能产生不利影响。

A feeding trial was conducted to examine the effects of feeding polyurethane coated urea on lactating performance and plasma biochemical indices of dairy cows. Twenty-four Holstein lactating cows were allotted to one of three treatments in a completely randomized design. The three treatments with isonitrogenous diets (17.0% CP) were: 1) diet with soybean meal （SBM group）; 2) diet with polyurethane coated urea （PCU group）; 3) diet with feed grade urea （FGU group）. The results showed as follows: compared with FGU group, dry matter intake of cows in PCU group and SBM group were significantly increased (12.8%, 12.6%, P=0.02); milk yield was increased from 32.48 kg/d to 34.48 and 34.53 kg/d, but no significant difference was found (P>0.05); milk protein yield tended to increase (P=0.06). Cows in FGU group had lower milk protein ratio (P=0.04) and higher milk urea nitrogen concentration (P=0.03) than those in the other two groups. Compared with FGU group, plasma urea nitrogen concentration in PCU group (16.7 mg/dL) and SBM group (16.4 mg/dL) were significantly decreased (P=0.05). Milk urea nitrogen had a positive correlation with plasma urea nitrogen (R2=0.85). It is concluded that polyurethane coated urea can partially substitute soybean meal in the diet of dairy cows without impairing their lactating performance.［Chinese Journal of Animal Nutrition, 2010，22（6）:1672-1678］