奶牛早孕诊断乳汁孕酮临界值的确定

随机选择健康荷斯坦母牛６３头，其中发情周期牛５头，配后１８－２４天牛３０头和通过直接确定的怀孕牛２８头，按程序采集末乳乳样。用放射免疫测定法（ＲＬＡ）测定乳汁孕酮（ＭＰ４）浓度。以发情第３天ＭＰ４浓度加上２倍标准差为未孕临界值的土限，以配后１８－２４天怀孕牛ＭＰ４浓度的平均值减去１倍标准差为怀孕临界值的下限。结果表明，奶牛ＭＰ４早孕诊断临界值为：≥７．１９ｎｇ／ｍｌ为怀孕，〈４．７２ｎｇ／ｍｌ为未

Determination of cow milk progesterone critical value for early pregnancy diagnosis

The end milk samples were collected from 63 random selected Holstein cows including 5 in estrous cycle, 30 inseminated after 18 to 24 days and 28 pregnant cows determined by rectal palpation, then testing the concentration of milk progesterone (MP 4). The MP 4 concentration plusing 2 times standard error at 3rd day of heat was considered as the ceiling of unpregnant critical value, the average MP 4 concentration subtracting 1 time standard error of pregnant cows inseminated after 18 to 24 days was regarded as the lower limit of pregancy critical value. The results showed that cow MP 4 early pregnancy diagnosis critical value is above or equal to 7.19ng/ml with pregnancy below 4.72ng/ml with unpregnancy, the critical value between 7.19ng/ml and 4.72ng/ml with dubious pregnancy. According to above standards, the definite pregnancy diagnosis rate is 92.30%, definite unpregnancy diagnosis rate is 100% for cows mated after 22 to 24 days. Therefore, the optimum milk sample collecting time for early pregnancy diagnosis is 22 to 24 days after inseminating.