Marinov S
Vet Med Nauki. 1981;18(1):32-8.
The interrelation between dietary protein, total protein level and blood serum urea, and conception rate in cows has been studied in the course of two four-month periods on two dairy farms with a total of 150 test cows that were fed on varying rations. It has been demonstrated that the level of serum urea corresponded to the amount of protein in the diet (in percent of dry matter) and could be used in meeting the protein requirements of cows. The content of total protein has not proved to be a suitable index for the same purpose. A weak or moderate negative correlation (from r=-0.07 to r=0.43) has been found to exist between the amount of total protein and that of urea in the serum. The correlation method of Orlov - Dounyov has been used to determine the interrelation between the level of total protein and urea in the blood serum, on the one hand, and the total conception, the conception rate at first insemination, and the cases of anaphrodisia, on the other. It has been found that cows with urea levels closer to the Blowey values (optimal level of 25 mg%) show higher conception rate. The high content of protein in the rations, resp. of urea in the blood serum is an important factor in the etiology of anaphrodisia in cows. No such correlation has been established with regard to total protein.
在两个奶牛场对总共150头试验奶牛进行了为期两个四个月的研究，这些奶牛饲喂不同的日粮，研究日粮蛋白质、总蛋白水平与血清尿素之间的相互关系以及奶牛的受孕率。结果表明，血清尿素水平与日粮中蛋白质含量（以干物质百分比计）相对应，可用于满足奶牛的蛋白质需求。总蛋白含量尚未被证明是用于同一目的的合适指标。已发现血清中总蛋白量与尿素量之间存在弱或中度负相关（r值从-0.07至0.43）。采用奥尔洛夫-杜尼奥夫相关方法来确定血清中总蛋白和尿素水平一方面与总受孕率、首次输精时的受孕率以及母牛性欲缺乏情况另一方面之间的相互关系。已发现尿素水平更接近布洛维值（最佳水平为25毫克%）的奶牛受孕率更高。日粮中蛋白质含量高，相应地血清中尿素含量高是奶牛性欲缺乏病因的一个重要因素。未发现与总蛋白有此类相关性。
