本试验旨在通过在饲粮中添加不同剂量的杜仲叶提取物,确定其在泌乳奶牛中的安全使用剂量。将60头泌乳高峰期荷斯坦奶牛按体重、胎次、泌乳天数和产奶量相同或相近的原则随机分为4组,每组15个重复,每个重复1头牛。对照组饲喂基础饲粮,试验组分别在基础饲粮上添加20、100和200 g/(d·头)杜仲叶提取物。预试期10 d,试验期60 d。结果表明:添加适量杜仲叶提取物[20 g/(d·头)]有提高奶牛干物质采食量的作用,同时对产奶量和乳脂率有明显提升作用,并可降低牛奶体细胞数;添加100 g/(d·头)杜仲叶提取物使奶牛干物质采食量比对照组降低了0.78%(P>0.05),且产奶量比对照组降低了1.38%(P>0.05);添加200 g/(d·头)杜仲叶提取物使奶牛干物质采食量比对照组显著降低了3.42%(P<0.05),且使牛奶体细胞数显著高于其他3组(P<0.05)。添加适量杜仲叶提取物[20 g/(d·头)]对奶牛营养物质的消化率有促进作用,但是添加高剂量杜仲叶提取物[200 g/(d·头)]对营养物质的消化具有抑制作用。添加高剂量杜仲叶提取物[100和200 g/(d·头)]未对奶牛血液指标产生不良影响。综上所述,同时结合生产实际,推荐以100 g/(d·头)杜仲叶提取物作为泌乳奶牛最高安全使用剂量。

This experiment was conducted to study the safety supplemental dosage of Eucommia ulmoides leaf extract for lactating dairy cows. Sixty Chinese Holstein cows were randomly allocated to 4 groups with 15 replicates per group and 1 cow per replicate based on the same weight, parity, duration of lactation and milk yield. The control group was fed with the basal diet, and the experimental groups were fed with the basal diet supplemented with 20, 100 and 200 g/(d·cow) Eucommia ulmoides leaf extract, respectively. The adaptation period to the diet was 10 days while the formal experimental period was 60 days. The results showed as follows: adding appropriate Eucommia ulmoides leaf extract [20 g/(d·cow) could increase dry matter intake, milk yield and milk fat percentage of lactating dairy cows, and decrease somatic cell count (SCC); the dry matter intake in 100 g/(d·cow) Eucommia ulmoides leaf extract group could be reduced by 0.78% compared with that in control group (P>0.05), and the milk yield decreased by 1.38% compared with that in control group (P>0.05); the dry matter intake in 200 g/(d·cow) Eucommia ulmoides leaf extract group could be significantly reduced by 3.42% compared with that in control group (P<0.05), and the SCC in 200 g/(d·cow) Eucommia ulmoides leaf extract group was significantly increased compared with that in the other three groups (P<0.05). Adding appropriate Eucommia ulmoides leaf extract [20 g/(d·cow) could increase dry matter intake, milk yield and milk fat percentage of lactating dairy cows, and decrease somatic cell count (SCC); the dry matter intake in 100 g/(d·cow) Eucommia ulmoides leaf extract group could be reduced by 0.78% compared with that in control group (P>0.05), and the milk yield decreased by 1.38% compared with that in control group (P>0.05); the dry matter intake in 200 g/(d·cow) Eucommia ulmoides leaf extract group could be significantly reduced by 3.42% compared with that in control group (P<0.05), and the SCC in 200 g/(d·cow) Eucommia ulmoides leaf extract group was significantly increased compared with that in the other three groups (P<0.05). Adding appropriate Eucommia ulmoides leaf extract [20 g/(d·cow)] could promote nutrient digestibility of lactating dairy cows, but adding high-dose Eucommia ulmoides leaf extract [200 g/(d·cow)] could cause the inhibition of nutrition digestion of lactating dairy cows. Adding high-dose Eucommia ulmoides leaf extract [100 and 200 g/(d·cow)] hadn't a negative effect on blood indices of lactating dairy cows. It is concluded that 100 g/(d·cow) Eucommia ulmoides leaf extract is advised as the highest dose of security based on production practice.