Accuracy of pregnancy/non pregnancy diagnosis in zebu and crossbred cattle and Murrah buffaloes by milk progesterone determination post insemination.

Milk samples collected on days 0, 6, 20, 22 and 24 post insemination from Sahiwal and Tharparkar (zebu) cows, Karan Swiss (Sahiwal x Brown Swiss) and Karan Fries (Tharparkar x Holstein Friesian) crossbred cows and Murrah buffaloes were analysed for progesterone by enzyme-linked immunosorbent assay to determine the accuracy of pregnancy and non pregnancy diagnosis in each of the 3 groups of animals. The accuracy of pregnancy diagnosis was markedly improved in cows when the milk progesterone values on days 20, 22 and 24 were considered together, and a further improvement when the levels on days 0, 6, 20, 22 and 24 were considered together particularly in crossbred cows. In contrast, buffaloes exhibited the highest degree of accuracy from samples collected on day 24, and improvement in accuracy was minimal when values were considered for all 5 days, viz. 0, 6, 20, 22 and 24 post insemination. Overall, the accuracy of positive pregnancy diagnosis was greatest in zebu cows (90.9%) followed by crossbred cows (86.6%) and Murrah buffaloes (76.5%) when milk progesterone values on all 5 days were considered. The accuracy for negative pregnancy diagnosis was 100% on all days. The results suggest that there is a greater variability in oestrous cycle length in cattle than in buffaloes, and embryonic mortality is greater in buffaloes than in cattle.