title: Development of estrous synchronization protocols using melengestrol acetate in Bos indicus cattle.
abstract: Five experiments were conducted on commercial farms in Brazil designed to develop the basis for an estrus synchronization protocol using melengestrol acetate (MGA) in Bos indicus cattle. These studies resulted in the development of the following protocol: 0.5 mg x d(-1) of MGA between d -14 and -1; 2.0 mg i.m. injection of estradiol cypionate on d -9; 48 h temporary weaning between d 0 and 2; and natural service beginning on d 0. The basis of this protocol was to induce estrous cyclicity before postpartum loss of body condition, prevent premature luteolysis, eliminate the need for labor required to detect estrus, and consequently increase the likelihood of pregnancy early during the postpartum period. This treatment effectively induced estrous cyclicity among anestrous cows, synchronized estrus activity, and prevented premature luteolysis with no negative effect on pregnancy.
authors.affiliation: Departamento de Produção Animal, Faculdade de Medicina Veterinária e Zootecnia-UNESP, Botucatu-SP 18618-000, Brazil.
authors.forename: O G
authors.initials: OG
authors.lastname: Sá Filho
authors.forename: D J
authors.initials: DJ
authors.lastname: Patterson
authors.forename: J L M
authors.initials: JL
authors.lastname: Vasconcelos
mesh_terms: D000818:Animals; D001823:Body Composition; D002417:Cattle / Q000502:physiology*; D004334:Drug Administration Schedule; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage / Q000494:pharmacology; D007315:Insemination, Artificial / Q000662:veterinary; D008552:Melengestrol Acetate / Q000008:administration & dosage* / Q000494:pharmacology*; D011247:Pregnancy; D018873:Pregnancy Rate; D014886:Weaning
chemical_list: D005300:Fertility Agents, Female; D004958:Estradiol; D008552:Melengestrol Acetate; C007630:estradiol 17 beta-cypionate