author(s)
R Suresh Kumar, K Krishnakumar, S Balasubramanian, K Vijayarani, Thilak Pon Jawahar, D. Balasubramaniyam and T Sarath

abstract
The present study was conducted in silent estrus buffaloes to estimate the concentration of estradiol 17-β and progesterone. Seven silent estrus buffaloes were selected and their cyclicity was confirmed by ovarian ultrasonography for three cycles. Similarly, seven normal estrus buffaloes were kept as control. Blood samples were collected during the different phases of cycle for estimating estradiol 17β and progesterone concentration. The mean estradiol-17β concentration (pg/ml) in silent estrus buffaloes was 4.28±0.08, 8.16±0.11, 3.12±0.23 and 2.80±0.15 during proestrus, estrus, metestrus and diestrus, respectively. In the normal estrus animals, it was 6.28±0.20, 16.36±0.18, 4.60±0.12 and 3.48±0.21 during similar phases respectively. Similarly, progesterone concentration (ng/ml) was 0.54±0.09, 0.36±0.56, 0.90±0.19 and 1.82±0.06 during proestrus, estrus, metestrus and diestrus, respectively in silent estrus buffaloes, where as it was 0.82±0.32, 0.72±0.14, 1.32±0.16 and 4.19±0.20 in the normal estrus buffaloes. The mean serum concentration of estradiol-17β was significantly lower during estrus in silent estrus when compared to the normal estrus buffaloes. Similarly, the serum progesterone concentration was also significantly low during diestrus in silent estrus buffaloes.