Comparative Evaluation of Ovsynch and Heatsynch Protocols on Reproductive Performance of Postpartum Anestrus Crossbred Dairy Cows under Field Conditions

Abstract

Abstract

Postpartum anoestrus is a reproductive constraint in dairy cattle, particularly in smallholder field systems where oestrus detection and reproductive management may be limited. This study evaluated responses in postpartum anoestrous crossbred cows subjected to Ovsynch and Heatsynch synchronisation protocols under field conditions in East Champaran district, Bihar, India. Sixty postpartum anoestrous crossbred cows were enrolled over two breeding seasons and allocated to three groups of 20 animals each. The control group received supportive management, whereas the treatment groups received either the Ovsynch or Heatsynch protocol, followed by artificial insemination according to the assigned schedule. Oestrus response, conception rate, body condition score, parity and study year effects were explored. Oestrus response was 45.0% in the control group, 80.0% in the Ovsynch group and 75.0% in the Heatsynch group. Both synchronisation protocols produced higher oestrus responses than supportive management alone, with the Ovsynch group showing a statistically significant improvement over the control group. Conception rates were 35.0%, 65.0% and 55.0% in the control, Ovsynch and Heatsynch groups, respectively. Conception was numerically higher in the synchronised groups, although the difference between Ovsynch and Heatsynch was not significant. Body condition score and parity were not significantly associated with conception outcome, although cows with body condition scores of ≥3.0 tended to perform better. Reproductive responses were broadly consistent across study years. These findings indicate that Ovsynch and Heatsynch may be useful reproductive management options for postpartum anoestrous crossbred cows under smallholder field conditions; however, larger studies are needed to confirm treatment effects with greater precision.