Abstract

The study compared a natural-service breeding (NSB) program to a single fixed-time artificial insemination (FTAI) program on beef cow reproductive efficiency, breeding costs and partial budget evaluation. Eighty Black Angus lactating beef cows (5-6 yrs of age; n = 80; BW = 599.4±78.6 kg) were randomly assigned by age, days postpartum to either FTAI (FTAI cow) or NSB (NSB cow) breeding program. The FTAI cows received a CIDR for 7 d and 100 μg (2 mL) i.m. injection of GnRH, following this 25 mg (5 mL) i.m. of PGF_2α i.m. with CIDR removed. Then a second 25 mg (5 mL) i.m. injection of GnRH approximately 66 h (d 10) after initial injection to ensure luteal regression, and artificially inseminated with semen by a trained technician. The NSB cows were exposed to bulls at a bull:cow ratio of 1:25 for a 63 d breeding season. Results indicated that a NSB program can be a lower cost ($85 vs. $123) compared to FTAI program on a per cow basis. If improvements in conception rate, calf weaning rate, and total 205 d adjusted wean weights are incorporated, a partial budget analysis reveals FTAI can increase net profit by $284 per cow.

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