|Day, Michael - OHIO STATE UNIVERSITY|
Submitted to: Ohio State University Extension Publication
Publication Type: Other
Publication Acceptance Date: June 13, 2005
Publication Date: June 13, 2005
Citation: Day, M.L., Geary, T.W. 2005. Handbook of estrous synchronization. Ohio State University Extension Publication. Wooster. Western Region Publication No. 014. 22 pp. Interpretive Summary: Producers may select from a wide variety of synchronization programs for use in beef cattle. These systems range from programs that are effective only in cyclic cattle to complex programs that regulate follicular development, provide multiple stimuli designed to induce anestrous females to cycle, and treatments that synchronize ovulation for the purposed of timed artificial insemination (AI). There is not a single program that can be identified as “ideal” for all situations. Goals for an AI program as well as management limitations/conditions need to be considered in choosing the appropriate protocol for a given scenario. The estrous cycle of a cow is described and factors affecting response to different protocols are explained in detail. All programs described have been demonstrated to provide acceptable results when used in the appropriate animals groups. Bos indicus cattle do not respond similarly to Bos taurus cattle when some protocols are used and producers are advised to use caution in selection of a protocol that has not been fully tested in Bos indicus cattle.
Technical Abstract: Synchronization of estrus or ovulation in beef cattle requires an understanding of the cow’s estrous cycle and factors that might limit response/success with specific programs. The cow generally has a 21 day estrous cycle that is controlled by hormonal communication between the various organs involved including the hypothalamus, pituitary, ovary, and uterus. The source, target, and role of each of these hormones are described. Synchronization of estrus involves use of some of these, or similar, hormones to manipulate the reproductive cycle of the cow so that a large number of cows can be bred by artificial insemination during a short period with minimal heat detection. Protocols described include single injection of prostaglandin (PGF), two injection PGF, melengestrol acetate + PGF, intravaginal progesterone-releasing insert (CIDR) + PGF, gonadotropin releasing hormone (GnRH) + PGF, and combinations thereof.