烟酸和烟酸铬对热应激奶牛产奶性能和血液激素水平的影响

用36头泌乳中期的荷斯坦奶牛按配对原则分为对照组、烟酸组和烟酸铬组,进行65 d的饲养试验。对照组为基础混合精料,烟酸组在混合精料中添加800 mg/kg的烟酸,烟酸铬组在混合精料中添加10 mg/kg的烟酸铬。结果表明:在夏季热应激条件下,烟酸和烟酸铬使奶牛的粗饲料采食量增加,产奶量分别比对照组提高4.86%和12.02%(P<0.05);烟酸铬组提高乳脂5.0%、乳蛋白2.8%、非脂固形物1.8%;烟酸和烟酸铬使血清PRL、T3、T4激素水平上升(P<0.05),对GLU影响不明显(P>0.05);烟酸对血清COR水平无显著影响,烟酸铬使血清COR水平降低8.80%(P<0.05)。

Effects of Niacin and Chromium Nicotinate on Dairy Performance and Serum Hormone Levels of Heat-stressed Dairy Cows

Thirty-six Holstein dairy cows in mid-term lactation period were randomly divided into control group,Niacin group and Chromium Nicotinate group.A feeding experiment had been carried out for 65 days,during which the Niacin group concentrate was added with 800 mg/kg Niacin,the Chromium Nicotinate group concentrate was added with 10 mg/kg Chromium Nicotinate.The results showed that Niacin and Chromium Nicotinate could improve the roughage intake and increase the milk yields by 4.86%and 12.02%(P<0.05) respectively in heat-stressed environment of summer.The levels of milk fat,milk protein and SNF were raised by 5%,2.8% and 1.8% respectively for the Chromium Nicotinate group.The serum levels of PRL,T_(3),T_(4)were all increased significantly(P<0.05) but GLU_()levels were not influenced significantly for Niacin group and Chromium Nicotinare group;the serum levels of COR of Chromium Nicotinare group decreased by 8.80%(P<0.05),but Niacin group was not significantly influenced compared with control group.