The effects of gonadotropin releasing hormone on conception in postpartum anestrus angus beef cows and heifers

The objective of this study was to determine if a pre synchronization gonadotropin releasing hormone (GnRH) injection would increase conception percentages in postpartum anestrous angus beef cows and heifers. Sixty-four Angus females (42 multiparous cows and 20 heifers) from the Angelo State University’s Management, Instruction and Research Center were randomly assigned to two treatments groups at the beginning of the study. The control group were administered a two shot prostaglandin estrous synchronization protocol. The treatment group were administered a GnRH injection thirteen days prior to the two shot prostaglandin synchronization protocol. However, only 30 females showed signs of estrus and were artificially inseminated. Results in cows and heifers were similar, and no differences were found among the two treatment groups (P>0.05). Differences might be noted with a larger number of females that show signs of estrus. Conception was recorded by the use of ultrasound, and is a viable management tool.