饲粮铜水平对奶牛生产性能、养分表观消化率及血清生化指标的影响

Effects of Dietary Copper Levels on Performance,Nutrient Apparent Digestibility and Serum Biochemical Indices of Lactating Dairy Cows

本试验旨在研究饲粮铜水平对奶牛生产性能、养分表观消化率及血清生化指标的影响。选取60头产奶量、泌乳天数及胎次相近的中国荷斯坦奶牛,按随机分配原则分为4组,各组饲粮中铜添加量分别为0(对照,Ⅰ组)、10(Ⅱ组)、15(Ⅲ组)和20 mg/kg(Ⅳ组),饲粮铜水平分别为8.09、18.09、23.09和28.09 mg/kg DM,每组15头,试验期共93 d。结果表明:1)与Ⅰ组相比,Ⅱ、Ⅲ与Ⅳ组的产奶量分别提高了4.91%、6.27%及4.78%(P<0.05),乳中体细胞数量极显著降低(P<0.01)。2)与Ⅰ组相比,Ⅱ和Ⅲ组的中性洗涤纤维(NDF)表观消化率分别提高了6.21%和7.60%(P<0.05),酸性洗涤纤维(ADF)表观消化率分别提高了6.78%和8.22%(P<0.05)。3)与Ⅰ组相比,Ⅱ、Ⅲ和Ⅳ组血清铜、铜蓝蛋白含量及超氧化物歧化酶(SOD)、铜-锌超氧化物歧化酶(Cu-Zn SOD)和谷胱甘肽过氧化物酶(GSH-Px)活性极显著提高(P<0.01),丙二醛(MDA)含量分别降低了50.00%、60.23%和47.08%(P<0.01),免疫球蛋白G(Ig G)含量分别提高了49.56%、165.56%和90.22%(P<0.01)。4)铜代谢指标分析说明,与Ⅰ组相比,饲粮中补充铜能极显著提高粪铜、尿铜含量(即粪和尿中铜的排出量)和铜沉积量(P<0.01),但饲粮铜水平对铜表观消化率没有显著影响(P>0.05)。在本试验条件下,饲粮中补充铜可提高奶牛的生产性能,促进机体对养分的利用,提高机体免疫力和抗氧化能力,但粪铜含量随着饲粮铜水平的增加而增加。综合考虑,在本试验条件下,奶牛饲粮适宜铜水平为18.09~23.09 mg/kg DM(铜采食量为403.59~514.21 mg/d)。

The objective of this study was to investigate the effects of dietary copper levels on the performance, nutrient apparent digestibility and serum biochemical indices of lactating dairy cows. A total of 60 China Holstein lactating dairy cows with similar milk yield, lactation days and parity were selected, and randomly divided into 4 groups with 15 in each group. The copper addition in diets were 0 （control, group Ⅰ）, 10 （group Ⅱ）, 15 （group Ⅲ）, and 20 mg/kg （group Ⅳ）, respectively, and the levels of dietary copper were 8.09, 18.09, 23.09 and 28.09 mg/kg DM, respectively. The whole trial lasted for 93 days. The results showed as follows： 1） compared with group Ⅰ, the milk yield in groups Ⅱ, Ⅲ and Ⅳ was increased by 4.91%, 6.27% and 4.78% （ P 〈0.05）, respectively, and the somatic cell count in milk in groups Ⅱ, Ⅲ and Ⅳ was significantly decreased （ P 〈0.01）. 2） Compared with group Ⅰ, the neutral detergent fiber （NDF） apparent digestibility in groups Ⅱ and Ⅲ was increased by 6.21% and 7.60% （ P 〈0.05）, and the acid detergent fiber （ADF） apparent was increased by 6.78% and 8.22% （ P 〈0.05）, respectively. 3） Compared with group Ⅰ, the contents of serum copper and ceruloplasmin, and the activities of superoxide dismutase （SOD）, copper-zinc superoxide dismutase （Cu-Zn SOD） and glutathion peroxidase （GSH-Px） in groups Ⅱ, Ⅲ and Ⅳ were significantly increased （ P 〈0.01）; the content of serum malonaldehyde （MDA） was decreased by 50.00%, 60.23% and 47.08% （ P 〈0.01）, respectively; the content of immunoglobulin G （IgG） was increased by 49.56% , 165.56% and 90.22% （ P 〈0.01）, respectively. 4） Analysis of the indicators of copper metabolism showed that supplemental copper could significantly increase the fecal copper and urine copper contents （excretion） and copper deposition （ P 〈0.01）, but the dietary copper level had no significant effect on the apparent digestibility of fecal copper （ P 〉0.05）. Under the condition of this experiment, diets supplemented with copper can improve the performance of lactating dairy cows, promote the utilization of nutrients and improve the body’s immunity and antioxidant capacity, but increasing copper level leads to an increase of fecal copper excretion. In this experiment, the suitable dietary copper level in the diet of lactating dairy cows is 18.09 to 23.09 mg/kg DM （copper intake is 403.59 to 514.21 mg/d）.