Advancements in Producer Applications
Estrous Synchronization Responses
The differences of estrous synchronization in Bos taurus and Bos indicus.
by Kasey Miller for Angus Productions Inc.
HOUSTON, Texas (April 20, 2012) — Estrous synchronization is a useful tool for artificially inseminating (AIing) females in the herd, but Bos taurus and Bos indicus cattle react differently to synchronization, Joel Yelich, University of Florida, told attendees of the Producer Applications Committee breakout session at the 2012 Beef Improvement Federation (BIF) Research Symposium and Annual Meeting in Houston April 18-21.
Estrous synchronization protocols designed for Bos taurus cattle do not work as well on Bos indicus cattle, Yelich said. AI pregnancy rates ( the percentage that got pregnant to AI of the total bred AI) are significantly lower among Bos indicus cattle, Yelich said.
“Bos indicus cattle have subtle differences in endocrine responses and follicular dynamics, and those may be to blame,” he added. Concentrations differ in levels of lutenizing hormones (LH), estradiol and progesterone. Estrus is also more difficult to detect among Bos indicus cattle because of decreased estrous duration and increased instances of silent heats. Management practices also play a larger role in AI success.
Yelich presented results of several studies. Seven-Day Select Synch plus CIDR® and Timed-AI (TAI) showed variable success, and many depended upon herd management. Five- and 7-Day Co-Synch plus CIDR showed very poor succes rates (33% compared to 62% in Bos taurus). He discouraged producers of Bos indicus cattle from using these methods.
There is potential, he said, in a modified 7-Day Select Synch plus CIDR and TAI, which reduces prostaglandin concentrations during follicle development wave for determined period of time. Research is being done at Texas A&M University on a protocol called “Bee Synch,” which is a modified 5-Day Co-Synch plus CIDR protocol that is showing promise in Bos indicus cattle.
“In this system, both prostaglandin and and gonadatropin-releasing hormone (GnRH) are administered at CIDR insertion, and all cattle receive timed-AI 66 hours after CIDR removal,” he said.
More research is being done to develop consistency in estrous synchronzation in Bos indicus cattle.
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