Effects of Synchro-Mate B and prostaglandin F2α on estrus synchronization and fertility in beef cattle

Abstract

The efficiency and precision of estrus synchronization and fertility were evaluated after prostaglandin F2α (PGF) treatment with or without pretreatment with Synchro-Mate B (SMB) in beef cattle. In the treatment group (SMB-PGF, n = 109), postpartum suckled (n = 53), and nonsuckled (n = 32) cows and virgin heifers (n = 24) received SMB for 9 d and PGF 72 h before implant withdrawal. In the control group (Control, n = 111), postpartum suckled (n = 51), and nonsuckled (n = 36) cows and virgin heifers (n = 24) were observed for estrus and bred at spontaneous estrus over a 6-d period. Those not detected in estrus were then injected with PGF and bred at induced estrus over an additional 6-d period. Synchronization rate at induced estrus was higher (95.4 vs. 84.2%, P < 0.01) and time interval from induction to onset of estrus was shorter (37.0 ± 2.1 h vs. 56.7 ± 2.8 h, P < 0.01) in the SMB-PGF group than after PGF in the Control group. Whether the time around the mean interval to estrus (precision) was ± 6, ± 12, ± 18 or ± 24 h, the synchronization rate was always higher (P < 0.01) in the SMB-PGF than in the Control group. Heifers and cows in both groups had similar estrus synchronization rates and mean intervals to estrus. Suckled and nonsuckled cows behaved similarly in their estrus response within the SMB-PGF group but not in the Control group. Our results indicate that administration of PGF 72 h before SMB implant withdrawal could be a very efficient and precise synchronization method without a negative effect on fertility in beef cattle. Key words: Estrus synchronization, beef cattle, Synchro-Mate B, prostaglandin F2α