Cattle Reproduction Research at CGREC
From the Winter 2017 issue of the Central Grasslands Forum
Carl Dahlen, NDSU Extension Beef Cattle Specialist
Since the spring of 2011, cows and heifers at the Central Grasslands REC have been synchronized and artificially inseminated (AI bred) using a program called the 7-day Co-Synch + CIDR protocol. It requires females be handled three times during a 10-day period.
Cows receive a controlled internal drug-releasing insert (CIDR) and an injection of gonadotrophin-releasing hormone (GnRH), followed in seven days by CIDR removal and an injection of prostaglandin F2α. That is followed in 60 to 66 hours (54 hours for heifers) by GnRH and fixed-time AI. Pregnancy rates from this single AI breeding have ranged from 48 to 65 percent, depending on the year.
Each year, the breeding is part of a research effort focused on improving the reproductive efficiency of beef herds. Estrus detection patches are placed on the tailhead of cows at the time of CIDR removal and evaluated at the time of AI; if patches are “activated,” or rubbed to expose color, the cow has been in heat.
This study found that an improved pregnancy rate is possible when AI breeding is delayed by 15 to 20 hours in cows that are not in heat at the time of normal AI breeding (i.e. cows in heat bred at 60 to 66 hours; cows not in heat bred 15 to 20 hours later). An additional effort found that GnRH was not needed at the time of AI if cows had been in heat, but it was essential for cows that had not been in heat.
Other efforts have evaluated the impacts of pre-breeding vaccines, management around the time of breeding and administration of injectable trace mineral supplements.
Coming up for the 2017 breeding season: All breeding females will serve as recipients for an embryo transfer study.
Photos by Carl Dahlen