奶牛围产前期钙的稳态和负DCAD日粮的应用

Calcium Homeostasis and Application of Negative DCAD Diet in Cows During Close-up Period

围产期是奶牛泌乳周期乃至一生中最为关键的阶段,围产期的饲养管理对奶牛整个泌乳期的产奶性能、繁殖性能和健康状况都有影响。鉴于围产期奶牛的营养和生理研究的不断深入,尤其是奶牛围产前期钙的稳态得到越来越多的关注,负日粮阴阳离子差(dietary cation-anion difference, DCAD)日粮,即阴离子日粮作为一种有益的探索在国外牛场获得大规模推广应用,本文在综合阐述钙的稳态、吸收、释放规律和负DCAD日粮的特征的基础上,对负DCAD日粮的应用提出生产上的建议:在合理的干物质采食量(dry matter intake, DMI)基础上,目前普遍使用负DCAD日粮和高钙水平相结合,设定-100~-150 meq/kg的DCAD水平,配合0.4%左右的高镁含量和低磷水平,对应尿液应该在pH 5.5~6.5。

Periparturition is the most critical period of lactation cycle and even the whole life of cows. The feeding management of periparturition has impacts on milking performance, reproductive performance and health status of cows in the whole lactation period. In view of the research about the nutrition and physiology of periparturition cows in recent years, especially that calcium homeostasis of cows during close-up period has been attached with more and more attention, negative DCAD(dietary cation-anion difference) diet or anionic diet has been widely promoted and applied in foreign farms as a beneficial exploration. Based on the comprehensive description of calcium homeostasis, absorption and release rules and the characteristics of negative DCAD diets, this article puts forward production recommendations for the application of negative DCAD diets. On the basis of reasonable DMI(dry matter intake), a combination of negative DCAD diets and high calcium levels is commonly used currently. Set the DCAD level of-100 to-150 meq/kg, combined with the high magnesium content of about 0.4% and low phosphorus level, the corresponding urine pH should be5.5 to 6.5.