title: Alternative programs for synchronizing and resynchronizing ovulation in beef cattle.
abstract: Fixed-time artificial insemination (FTAI) has been regarded as the most useful method to increase the number of cows inseminated in a given herd. The main treatments for FTAI in beef cattle are based on the use of progesterone-releasing devices and GnRH or estradiol to synchronize follicle wave emergence, with a mean pregnancy per AI (P/AI) around 50%. However, more recent protocols based on GnRH (named 5-day Co-Synch) or estradiol (named J-Synch) that reduce the period of progesterone device insertion and extend the period from device removal to FTAI have been reported to improve P/AI in beef cattle. Furthermore, treatments to resynchronize ovulation for a second FTAI in nonpregnant cows have provided the opportunity to do sequential inseminations and achieve high P/AI in a breeding season, reducing or even eliminating the need for clean-up bulls. In summary, FTAI protocols have facilitated the widespread application of AI in beef cattle, primarily by eliminating the necessity of estrus detection in beef herds.
authors.affiliation: Instituto A.P. de Ciencias Básicas y Aplicadas, Carrera de Medicina Veterinaria, Universidad Nacional de Villa María, Córdoba, Argentina; Instituto de Reproducción Animal Córdoba (IRAC), Zona Rural General Paz, Córdoba, Argentina. Electronic address: gabrielbo62@gmail.com.
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Bó
authors.affiliation: Instituto A.P. de Ciencias Básicas y Aplicadas, Carrera de Medicina Veterinaria, Universidad Nacional de Villa María, Córdoba, Argentina; Private Practice and M.Sc. Program in Bovine Reproduction, IRAC-FCA, Universidad Nacional de Cordoba, Argentina.
authors.forename: José Javier
authors.initials: JJ
authors.lastname: de la Mata
authors.affiliation: Departamento de Reprodução Animal, FMVZ-USP, São Paulo, Brazil.
authors.forename: Pietro S
authors.initials: PS
authors.lastname: Baruselli
authors.affiliation: Fundación IRAUy, Instituto de Reproducción Animal Uruguay, Montevideo, Uruguay.
authors.forename: Alejo
authors.initials: A
authors.lastname: Menchaca
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D004973:Estrus Synchronization / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006728:Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D007315:Insemination, Artificial / Q000502:physiology / Q000662:veterinary; D010060:Ovulation / Q000187:drug effects*; D011247:Pregnancy
chemical_list: D006728:Hormones
keywords: Beef cattle; Estradiol; Fixed-time artificial insemination; GnRH; Progesterone