Resumption of ovarian cyclicity and fertility response in bull-exposed postpartum buffaloes

A study was undertaken to evaluate the effect of bull exposure on resumption of ovarian cyclicity and fertility response in postpartum buffaloes raised under standard farm conditions. A total of 24 Murrah buffaloes was randomly grouped to receive one of the following treatments: (1) exposure to a vasectomised bull from 40th to 90th day postpartum (bull-exposed. BE, n = 11) and (2) isolated from bull (non-exposed. NE, n = 13). Changes in the progesterone concentration were used to assess the resumption of ovarian cyclicity. Postpartum interval to resumption of ovarian cyclicity (47 +/- 2.58 days vs. 56 +/- 2.37 days, p < 0.05) as well as behavioral estrus (57 +/- 3.61 days vs. 71 +/- 5.13 days, p < 0.05) was shorter in bull-exposed animals than control animals. Similarly, animals in the BE group had significantly shorter interval to postpartum ovulation (48 +/- 2.69 days vs. 57 +/- 2.37 days, p < 0.05). Reduced incidence of silent ovulation was observed in BE group compared to NE group (18.18% vs. 50%). More than half proportion of animals in BE group conceived by 60 days postpartum compared to a very low proportion of animals in NE group (54% vs. 15%, p < 0.05). Furthermore, first service conception rate in BE animals was significantly greater than NE animals (100% vs. 37.50%, p < 0.05). In conclusion, continuous bull exposure to buffaloes during later postpartum period accelerates resumption of ovarian cyclicity, reduces incidence of silent ovulation and enhances first service conception rate. These results indicate that introduction of bulls to buffalo herd could be a rational management strategy for reducing the postpartum anestrus by enhancing reproductive function in buffaloes. (C) 2010 Elsevier B.V. All rights reserved.