Early pregnancy diagnosis in cattle
Wishart, D.F.
Veterinary Record 96(2): 34-38
1975
ISSN/ISBN: 0042-4900 PMID: 1114632 Document Number: 84174
Heifers were considered to be pregnant if their plasma progesterone levels were >3 ng/ml on days 20 and 23 after AI. Of 137 assays which indicated non-pregnancy, 97% were confirmed by rectal palpation 60-90 days after AI, and of 91 assays which indicated pregnancy, 85.5% were confirmed. Significant differences were found in the progesterone levels of morning "first milk" between 6 pregnant and 6 non-pregnant cows, both 21 and 24 days after AI.