11 CALF REMOVAL IMPROVES CO-SYNCH + CONTROLLED INTERNAL DRUG-RELEASE PREGNANCY RATES IN BEEF COWS
D. J. Kesler A , D. B. Faulkner A , F. A. Ireland A , J. Dahlquist A , S. Z. El-Zarkouny A and C. E. Ferguson BA Department of Animal Sciences, University of Illinois, Urbana, IL, USA;
B Department of Agriculture, McNeese State University, Lake Charles, LA, USA
Reproduction, Fertility and Development 21(1) 105-106 https://doi.org/10.1071/RDv21n1Ab11
Published: 9 December 2008
Abstract
Improving AI pregnancy rates in beef cattle will enhance the profitability of beef herds during these current times of increasing cost inputs by enhancing the quality of the calf crop. This experiment was aimed at determining the effect of calf removal (from CIDR removal to timed AI) during estrous cycle synchronization on AI pregnancy rates. This experiment was conduced at the Dixon Springs Research Station (Simpson, IL) during the fall 2007 breeding season. The beef cows used for this research project were crossbred Angus cows between 2 and 8 years of age that had calved in August to October of 2007. Cows were at least 45 days postpartum at the timed AI (November 2007). All cows were randomly divided into 1 of 2 treatment groups: cows in treatment group 1 (control group, n = 284) were allowed to keep their calves for the entire estrous cycle synchronization and AI program (except during brief times of treatment administration), whereas cows allotted to treatment group 2 (n = 258) had their calves removed at the time of CIDR implant removal/PGF2α treatment and returned following AI. The calves were maintained on creep feed out of sight and sound of their dams. All cows were synchronized by using the CO-Synch + CIDR protocol [CIDR (1.38 g) + GnRH (100 μg) on Day 0 and CIDR removal on Day 7 + PGF2α (25 mg)] and were inseminated at a predetermined time of 60 to 66 h post PGF2α with semen from proven bulls. At AI, cows also received an injection of GnRH (100 μg). All cows were pregnancy checked 50 to 65 days after timed AI via ultrasonography. Statistical comparisons were performed by using the chi-square test of SAS. The pregnancy rate for cows in the control treatment group was 47% (132 of 284) and was 57% (147 of 258) for the calf-removal treatment group. There was a significant increase in pregnancy rate in the treatment group (P < 0.02) that resulted in 10 more calves per 100 synchronized AI breedings. Although excellent facilities are needed to maintain calves away from their dams during this 60 to 66 h and there are additional costs for the feedings required for the calves, there is a savings in time (one calf separation from the cow is eliminated). In conclusion, removing the calves at the onset of estrous cycle synchronization can improve pregnancy rates to synchronized timed AI and can increase the ease of cattle handling during this process by reducing the number of calf removals during routine cow workings.
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