Presynchronization with Progesterone for Induction of Cyclicity in Bos Taurus Indicus Cows in Postpartum Anestrus Period

Abstract

Objective: The objective of this study was to evaluate the effect of pre-synchronization with progesterone (P4) for 3 and 6 days in Nelore cows in postpartum anestrus period, submitted to a fixed-time artificial insemination program (FTAI). Materials and methods: Seventy-four multiparous Nelore cows with a body condition of 2.5 were used. The cows were submitted to three experimental groups, control group and groups pre-synchronized with P4 for a period of 3 and 6 days. For the determination of postpartum anestrus status, ultrasound scans and blood samples were taken to verify the absence of endogenous P4. Forty-five days after AI, gestation was diagnosed. Data were obtained by descriptive analysis and in the case of presentation of significant differences the Chi-square test was used, considering a frequency of P < 0.05. Results: A higher gestation rate was observed for the group that was pre-synchronized for three days with P4 (40 %), in relation to the groups of six days of pre-synchronization and control (25 % and 32 %, respectively). Conclusion: It is possible to conclude that the pre-synchronization with P4 for three days improved the gestation rate of Nelore cows in the postpartum anestrus period