日粮中钙磷水平对奶牛生长性能、血液生化指标及钙磷代谢的影响

Effects of calcium and phosphorus levels on growth performance,blood biochemical indexes and mineral metabolism of dairy cows

文章旨在研究不同钙、磷水平对奶牛生长性能、血液生化指标及钙磷代谢的影响。试验选取60头生长状况相近的健康奶牛,随机分为4组,饲喂4种不同钙磷水平的饲料,钙磷水平为0.46%、0.22%(T1组),0.61%、0.29%(T2组),0.78%、0.37%(T3组)和0.91%、0.45%(T4组)。试验结果表明,适量的钙磷水平可以促进奶牛的生长,随着钙磷含量的增加,奶牛平均日采食量和日增重有先增加后降低的趋势,T2和T3组有最高的日采食量和最低的料重比,两者没有显著差异(P>0.05),钙磷水平过低和过高都不利于生长;随着钙磷水平的提高,奶牛血清中骨钙素(BGP)、降钙素(CT)含量和碱性磷酸酶(ALP)活性都有不同程度的提高,甲状腺旁激素(PTH)含量呈下降趋势,从而保证血液中钙、磷和镁水平正常;T4组奶牛血液中钙浓度偏高,其他组血液中钙、磷和镁浓度相对比较稳定。综上所述,适当提高日粮钙磷水平可以改善奶牛的生长性能,维持血液中钙磷代谢稳态,推荐250 kg 14月龄奶牛的日粮适宜钙水平为0.61%、磷水平为0.29%。

The effects of different calcium and phosphorus levels on growth performance,blood biochemical indexes and mineral element metabolism of dairy cows were studied to determine the appropriate dietary calcium and phosphorus levels.Sixty healthy 14-month-old Holstein cows with similar growth conditions were randomly divided into 4 groups and fed with four different levels of calcium and phosphorus.The results showed that proper calcium and phosphorus levels could promote the growth of dairy cows.With the increase of calcium and phosphorus content,the average daily feed intake and daily gain of dairy cows increased at first and then decreased.T2 and T3 groups had the highest daily feed intake and the lowest feed weight ratio.There was no significant difference between the two groups(P>0.05).Too low and too high levels of calcium and phosphorus are not conducive to growth.With the increase of the level of calcium and phosphorus,the contents of BGP,CT and ALP in serum of dairy cows increased in varying degrees,while the content of PTH decreased,thus ensuring the normal levels of calcium,phosphorus and magnesium in blood.Too low or too high concentration of calcium and phosphorus will change the blood biochemical indexes and mineral metabolism.The concentration of calcium in the blood of dairy cows in T4 group is high,while the concentrations of calcium,phosphorus and magnesium in other groups are relatively stable.To sum up,properly increasing the dietary calcium and phosphorus level can improve the growth performance of dairy cows and maintain the homeostasis of calcium and phosphorus metabolism in the blood.It is recommended that the appropriate dietary calcium level and phosphorus level of 250 kg 14-monthold dairy cows are 0.61%and 0.29%respectively.