Abstract #T148

# T148
Utilization of fixed-time artificial insemination (TAI) to reduce breeding season length and its effects on subsequent calf value: A case study.
Vitor R. G. Mercadante*1, Darren D. Henry1, Francine M. Ciriaco1, Guilherme H. L. Marquezini1, Tera E. Black1, Kalyn M. Waters1, Pedro L. P. Fontes1, Nicolas DiLorenzo1, G. Cliff Lamb1, 1North Florida Research and Education Center, University of Florida, Marianna, FL.

The development of TAI protocols has resulted in the opportunity for increased application of AI in commercial cattle operations. However, the long-term production and economic impact of implementing a TAI protocol in beef cattle operations has not been evaluated. Therefore, during an 8-yr period we evaluated the impacts of TAI to reduce the length of the breeding season (BS) and its effects on subsequent calving distribution, calf value, and BS pregnancy rates. The North Florida Research and Education Center consists of a beef herd containing 300 cows of Angus, Brangus, and Braford breed origin. During the 2006 and 2007 BS, the cows were exposed to a 120 d BS by natural service. In 2008, and every subsequent BS to 2013, all females were exposed to TAI using either the 5-d or 7-d CO-Synch+CIDR protocols. Initially, calving season length resulted in cows being inseminated in 3 TAI groups (in the 2008 and 2009 BS), subsequently reduced to 2 TAI groups (in the 2010 and 2011 BS), and eventually to a single TAI group (in the 2012 and 2013 BS). Following the initial TAI for each group, females were detected for estrus and inseminated artificially after an observed estrus until d 23 after TAI. On d 23 after TAI, bulls were introduced and cows were naturally mated for the remainder of the BS. All bulls passed a breeding soundness examination before being introduced to cows. The BS length was reduced from 120 to 70 d between the 2008 and 2013 BS. Calf distribution and subsequent weaning performance were determined. Overall pregnancy rates increased from 81% and 86% in the 2006 and 2007 BS, respectively, to 94% and 93% in 2012 and 2013, respectively. Mean calving date from the first calf born during each calving season was reduced from 80.9 d from the 2007 BS to 38.9 d from the 2013 BS. Utilizing a similar calf value across years of $0.91/kg, the mean value per calf increased by $87 per calf resulting from the 2008 BS to $169 per calf resulting from the 2013 BS. We conclude that exposing beef females to TAI and reducing the BS length for 6 years altered calving distribution, increased breeding season pregnancy rates, and increased calf value.

Key Words: fixed-time artificial insemination, economics, calving distribution