RELATIONSHIP OF PROGESTERONE IN PLASMA AND WHOLE MILK OF BUFFALOS DURING CYCLICITY AND EARLY-PREGNANCY

Blood and milk samples were collected on alternate days from 5 cycling buffaloes on 16 occasions and 2 pregnant buffaloes on 13 and 8 occasi ons. The blood and milk samples were analysed for progesterone by sens itive direct radioimmunoassay (RIA) procedures developed in this labor atory. The calculated correlation values (r) between plasma and milk p rogesterone concentrations during cyclicity were 0.8143, 0.5454 and 0. 8147 on 0 to 4, 6 to 14 and -6 to -2 days, prior to next oestrus (day 0 = day of oestrus) and the correlations for individual buffaloes duri ng cyclicity were in the range of 0.82 to 0.89 for plasma and milk pro gesterone concentration. The correlation between milk and plasma level s during early pregnancy in buffaloes was very low (0.1472). The linea r regression equation between milk (Y, ng/ml) and plasma (X, ng/ml) pr ogesterone concentration was Y = 1.8 + 3.61 X which indicated that the milk progesterone levels were about 4 times higher than those in plas ma. It was concluded from this study that in certain situations, such as during cyclicity when large variations occur in corpus luteum activ ity, the milk and plasma progesterone concentrations from the same buf falo are highly correlated. However, the correlation is very poor when corpus luteum activity remains more or less unchanged, as seen during pregnancy.