Research of diagnosis of early pregnancy of Chinese holstein cows by measuring the contenets of progesterone and oestraniol in milk

The contents of progesterone(P), oestradiol(E2) and P/E2 ratio in the milk of Chinese Holstein cows in and around breeding days were measured with radioimmunoassay, and the relations between the contents of P and E2 and cow conceiving were evaluated. The results indicated that the difference between the P content in the milk of the pregnant and the non- pregnant cows before breeding was not significant, but the P content from the first to the 18th day before breeding was highly significant(P<0.01). P content in the milk from the 7th to 9th day after breeding between the pregnant and the non-pregnant cows started to be significantly difference (P<0.01), and the difference became even bigger at significant with the breeding time. The E2 content in the milk of the pregnant and the non-pregnant cows was highly significant difference (P<0.01). From the 19th to 21th day after breeding, the E2 content in the milk of the pregnant cows was nearly two times as higher as that in the non-pregnant cows. The P content between the pregnant and the non-pregnant cows was significant difference (P< 0.05), the E2 content was not significant, and the P/E2 ratio was highly significant difference (P<0.01). (authors)