Pregnancy test and evaluation of embryonic and fetal mortality based on progesterone concentrations fore-milk.

Abstract

Results of fore-milk progesterone estimations from suckler beef cows using radioimmunoassay for pregnancy diagnosis and, with manual examination per rectum, the measurement of embryonic fetal mortality are reported. 79 milk samples from 47 multiparous Hereford cross-British-Friesian cows were assayed. Milk was sampled on Day 22 postmating. Both ovaries were examined per rectum to identify the presence of absence of a corpus luteum verum. After a draw of milk to clean the teat sinuses, 5 ml from each quarter were collected. Potassium dichromate was used as a preservative and milk stored at 5 degrees C until examined. Milk progesterone levels were 60% lower than those reported for dairy herds. Butter fat content of the fore-milk was 1%. Mean milk progesterone levels for positive cows was 9.6 ng/ml (range, 3.4-23.6) and for negative cows 2.0 ng/ml (range, 1.0-4.3 mg/ml). A level of 3.2 ng/ml was arbitrarily taken as the dividing line between positive and negative reports. There were 3 false positive reports. During lactation, progesterone levels and fat content continued to rise. The fore-milk samples from suckler beef cows were of value in the early detection of nonpregnant cows. The embryonic fetal mortality limited the value for pregnant cows but indicated the incidence of this condition.