Enzyme Immunoassays of Progesterone in Bovine Plasma and Skim Milk and Its Application to Early Pregnancy Diagnosis

Abstract

Progesterone concentrations (PC's) in blood plasma and skim milk were estimated by enzyme immunoassay (EIA) in dairy cows in the estrous period and in pregnant cows. Samples were collected nine times at 3 days' intervals after estrus or insemination and examined by an EIA kit produced in West Germany. Pregnancy was diagnosed by the non-return method and rectal examination.
When examined 22 days of the expectant day of next estrus, both plasma and milk PC's wre significantly higher (P<0.01) in the pregnant cows than in the other cows. When 88 dairy cows wre examined 21-23 days after insemination, there was a significant correlation (P<0.01) between plasma and milk PC's in them.
The hitting rate of pregnancy and that of sterility were calculated on the condition that pregnancy was positive when PC was 1 ng/ml or more. They were 81.6%(40/49) and 97.4%(38/39), respectively, as calculated from plasma PC, and 76.9%(30/39) and 88.4%(38/43), respectively, as calculated from milk PC. PC's were indicated to be of practical value for diagnosis of early pregnancy in cows.