title: Superovulatory response of zebu cows treated with pFSH in a single subcutaneous injection followed by an additional intramuscular sub-dose 48 h later.
abstract: The aim of this study was to evaluate whether an additional intramuscular (im) injection of pFSH would increase the embryo production in zebu cows superovulated with a single subcutaneous (sc) pFSH injection. Twenty-one Nelore cows were treated with a progesterone vaginal implant (Controlled Internal Drug Relased - CIDR B) and injected im with 2.5 mg estradiol benzoate. Four days later, cows were assigned randomly into three groups and superovulated with pFSH. Groups A and B received single sc injections of 400 and 320 IU, respectively; Group C received multiple im injections of 400 IU in decreasing doses at 12-h intervals over 4 days. In the morning (07:00 am) of day 3 after starting superovulation, cows received im 150 mcg cloprostenol and Group B was additionally injected im with 80 IU of pFSH. CIDR-B was withdrawn in the afternoon (07:00 pm). Cows were inseminated 48 and 62 h after the cloprostenol injection. Embryo collection and corpora lutea (CL) estimation were done 7 days after insemination. Alternation of treatments (crossover design) occurred at a 60-day interval. There was no significant difference (p > 0.05) of CL counts among treatments. The total (transferable and no transferable) number of recovered embryos from Group A (6.9 +/- 1.5) was not different from Group C (9.8 +/- 1.2), whereas Group B (5.7 +/- 1.5) was lower than Group C (p < 0.05). The number of transferable embryos from Groups A (2.4 +/- 0.7) and B (1.7 +/- 0.6) was lower (p < 0.05) than Group C (4.6 +/- 1.2). Lesser (p < 0.05) embryo production from Group B was related to lower recovery rate (46.4%), compared with Groups A (65.1%) and C (81.7%). It was concluded that an additional im subdose of pFSH, injected 48 h after a single subcutaneous (sc) dose of pFSH, does not improve the embryo production in zebu cows.
authors.affiliation: Genetic and Animal Reproduction Center, Instituto de Zootecnia - APTA, Nova Odessa São Paulo, Brazil. herrera@iz.sp.gov.br
authors.forename: R H
authors.initials: RH
authors.lastname: Alvarez
authors.forename: A C
authors.initials: AC
authors.lastname: Martinez
authors.forename: R M L
authors.initials: RM
authors.lastname: Pires
mesh_terms: D000818:Animals; D002417:Cattle / Q000196:embryology / Q000502:physiology*; D004624:Embryo Transfer / Q000662:veterinary; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage*; D007273:Injections, Intramuscular / Q000662:veterinary; D007279:Injections, Subcutaneous / Q000662:veterinary; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage; D013480:Superovulation; D020858:Tissue and Organ Harvesting / Q000662:veterinary
chemical_list: C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone