title: Comparison of the effects of pretreatment with Veramix sponge (medroxyprogesterone acetate) or CIDR (natural progesterone) in combination with an injection of estradiol-17β on ovarian activity, endocrine profiles, and embryo yields in cyclic ewes superovulated in the multiple-dose Folltropin-V (porcine FSH) regimen.
abstract: Follicular wave status at the beginning of exogenous FSH administration is an important contributor to variability in superovulatory responses in ruminants. Studies in ewes have shown a decrease in the number of ovulations when superovulation is initiated in the presence of ostensibly ovulatory-sized ovarian follicles. Hormonal ablation of large antral follicles with the progestin-estradiol (E2-17β) treatment significantly reduces this variability in superovulated anestrous ewes, but the effects of the treatment in cycling ewes have not yet been assessed. Sixteen Rideau Arcott × Polled Dorset ewes (November-December) received either medroxyprogesterone acetate (MAP)-releasing intravaginal sponges (60 mg) or controlled internal drug release (CIDR) devices (containing 300 mg of natural progesterone) for 14 days (Days 0-14), with a single intramuscular injection of 350 μg of E2-17β on Day 6. The superovulatory treatment consisted of six injections of porcine FSH (Folltropin-V) given twice daily, followed by a bolus GnRH injection (50 μg intramuscular) on Day 15. There were no differences (P < 0.05) in the ovulatory responses and embryo yields between the two groups of ewes. In both subsets of animals, the next follicular wave emerged ∼2.5 days after an E2-17β injection (P > 0.05). A decline in maximum follicle size after an E2-17β injection was more abrupt in CIDR- compared with MAP-treated animals, and the ewes pretreated with exogenous progesterone had significantly more 3-mm follicles at the start of the superovulatory treatment. The metabolic clearance rate of exogenous E2-17β appeared to be greater in MAP-treated ewes, but circulating concentrations of porcine FSH failed to increase significantly after each Folltropin-V injection in CIDR-treated animals. The CIDR-treated ewes exceeded (P < 0.05) their MAP-treated counterparts in serum E2-17β concentrations during superovulation. In spite of differences in antral follicle numbers and endocrine profiles between MAP- and CIDR-treated cyclic ewes receiving E2-17β before ovarian superstimulation, there were no differences in superovulatory responses.
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada. Electronic address: pmbart@uoguelph.ca.
authors.forename: Pawel M
authors.initials: PM
authors.lastname: Bartlewski
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Patricia
authors.initials: P
authors.lastname: Seaton
authors.affiliation: Department of Animal Biotechnology, Agricultural University of Cracow, Kraków, Poland.
authors.forename: Patrycja
authors.initials: P
authors.lastname: Szpila
authors.affiliation: Department of Preventative Veterinary Medicine and Animal Reproduction, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil.
authors.forename: Maria E F
authors.initials: ME
authors.lastname: Oliveira
authors.affiliation: Department of Animal Biotechnology, Agricultural University of Cracow, Kraków, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Murawski
authors.affiliation: Institute of Animal Sciences, Agricultural University of Cracow, Kraków, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Schwarz
authors.affiliation: Department of Animal Production, Jordan University of Science and Technology, Irbid, Jordan.
authors.forename: Rami T
authors.initials: RT
authors.lastname: Kridli
authors.affiliation: Department of Animal Biotechnology, Agricultural University of Cracow, Kraków, Poland.
authors.forename: Dorota A
authors.initials: DA
authors.lastname: Zieba
mesh_terms: D000282:Administration, Intravaginal; D000818:Animals; D019924:Embryo Disposition / Q000662:veterinary; D004958:Estradiol / Q000008:administration & dosage* / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage / Q000097:blood; D007273:Injections, Intramuscular / Q000662:veterinary; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging; D010053:Ovary / Q000187:drug effects* / Q000502:physiology; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage* / Q000097:blood; D012756:Sheep / Q000502:physiology*; D013480:Superovulation / Q000187:drug effects*; D013552:Swine; D014463:Ultrasonography
chemical_list: D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D017258:Medroxyprogesterone Acetate
keywords: Antral follicle; Estradiol; Progestin; Sheep; Superovulation; Ultrasonography