Quantitative relationships between oestradiol-17beta in the milk and blood of lactating buffaloes

The concentration of oestradiol-17beta was measured by radioimmunoassay in the milk and blood of lactating buffaloes after insemination. The concentration of oestradiol-17beta in milk was observed to be two to three times higher when compared with that in plasma samples. Major peaks of oestradiol-17beta in milk coincided with similar but smaller peaks occurring in plasma samples. In animals which were not pregnant, the major peak of oestradiol-17beta was recorded on the day of oestrus.