饲粮钙水平对泌乳奶牛钙代谢的影响

Effects of Dietary Calcium Level on Calcium Metabolism in Lactating Dairy Cows

通过研究饲粮钙水平对泌乳早期奶牛干物质采食量、产奶量及血液、尿液指标的影响,旨在探讨泌乳早期奶牛饲粮的适宜钙水平。试验选用4头泌乳3个月的荷斯坦奶牛[产奶量(20.33±0.92)kg],采用4×4拉丁方设计,饲粮钙水平(干物质基础)为0.50%、0.68%、0.83%和0.96%。结果表明:1)0.50%、0.68%、0.83%3个处理干物质采食量显著高于0.96%处理(P<0.05),3个处理间差异不显著(P>0.05);0.68%处理产奶量显著高于其他3个处理(P<0.05)。2)随着饲粮钙水平的升高,泌乳奶牛钙表观消化率逐渐降低,粪钙、尿钙浓度上升,0.50%处理钙表观消化率显著高于其他处理(P<0.05),尿钙/尿肌酐显著低于其他处理(P<0.05),0.68%处理与0.83%处理差异不显著(P>0.05);0.96%处理粪钙浓度显著高于0.50%处理(P<0.05),0.50%、0.68%、0.83%3个处理间差异不显著(P>0.05)。3)随着饲粮钙水平的升高,血液pH和尿液pH逐渐升高,0.96%处理显著高于0.50%处理(P<0.05),0.50%、0.68%和0.83%3个处理之间差异不显著(P>0.05)。4)血浆碱性磷酸酶活性、降钙素、骨钙素浓度逐渐升高,0.96%处理显著高于0.50%处理(P<0.05),0.50%处理与0.68%处理差异不显著(P>0.05);血浆甲状旁腺素浓度逐渐降低,0.50%处理显著高于其他组(P<0.05)。综合各指标可知,泌乳早期荷斯坦奶牛饲粮的适宜钙水平为0.68%(干物质基础)。

The effects of dietary calcium level on dry matter intake,milk yield,blood and urine parameters were observed in the present experiment to investigate an optimum calcium level in diets of early lactating dairy cows.Four Holstein cows [lactating for three months,milk yield （20.33±0.92） kg] were used in a 4×4 Latin square experiment.Dietary calcium levels of the four treatments were 0.50%,0.68%,0.83% and 0.96% （DM basis）,respectively.The results indicated as follows：1） dry matter intake of 0.50%,0.68% and 0.83% treatments was significantly higher than that of 0.96% treatment （P〈0.05）,but there were no significant differences among 0.50%,0.68% and 0.83% treatments （P〉0.05）;milk yield of 0.68% treatment was significantly higher than that of the other groups （P〈0.05）.2） With dietary calcium level increasing,apparent calcium digestibility of lactating dairy cow was decreased,but the concentrations of feces calcium and urine calcium were increased,and the apparent calcium digestibility of 0.50% treatment was significantly higher than that of the other groups （P〈0.05）,while urine calcium/urine creatinine of 0.50% treatment was significantly lower than that of the other groups （P〈0.05）,but there was no significant difference between 0.68% and 0.83% treatments （P〉0.05）;feces calcium concentration of 0.96% treatment was significantly higher than that of 0.50% treatment （P〈0.05）,but there were no significant differences among 0.50%,0.68% and 0.83% treatments （P〉0.05）.3） With dietary calcium level increasing,blood pH and urine pH were increased （P〈0.05）,and 0.96% treatment was significantly higher than 0.50% treatment （P〈0.05）,but there were no significant differences among 0.50%,0.68% and 0.83% treatments （P〉0.05）.4） With dietary calcium level increasing,plasma ALP activity,CT and BGP concentrations were increased,and 0.96% treatment was significantly higher than 0.50% treatment （P〈0.05）,but there was no significant difference between 0.68% and 0.83% treatments （P〉0.05）;plasma PTH concentration was decreased,and 0.50% treatment was significantly higher than the other groups （P〈0.05）.In conclusion,the optimum dietary calcium level for early lactating Holstein dairy cows is 0.68% （DM basis）.