Influence of gestation on blood plasma concentrations of oestrone and oestrone sulphate in Karan Swiss cows and Murrah buffaloes

Single blood samples from 106 pregnant and seven non-pregnant Karan Swiss cows and 104 pregnant and nine non-pregnant Murrah buffaloes were measured for oestrone and oestrone sulphate hormones by radioimmunoassay. Mean plasma oestrone level was below detection limit (less than 2.5 pg/ml) in non-pregnant and 1 month pregnant cows and buffaloes. In cows the mean oestrone level fluctuated narrowly between 10.25 and 26.65 pg/ml between the second and eight months of pregnancy, followed by a steep rise in the ninth and especially in the tenth month (151.24 pg/ml). In buffaloes mean oestrone concentrations were lower and fluctuated between 14.81 and 23.56 pg/ml during the second to ninth months of pregnancy, rising sharply in the tenth month to a peak of 47.37 pg/ml. Mean oestrone sulphate levels were below detection limit (less than 16 pg/ml) during non-pregnancy, first and second months of pregnancy in cows, increasing sharply thereafter to a peak of 6401.38 pg/ml in the tenth month of pregnancy. In buffaloes, low mean levels of oestrone sulphate were recorded in the non-pregnant and up to the fourth month of pregnancy with the levels rising sharply thereafter to a peak of 6559.82 pg/ml in the tenth month. The hormone levels were not significantly different in the two species (P greater than 0.01). The possibility of using oestrone sulphate measurement as a test of pregnancy confirmation has been indicated for both species.