title: The effect of treatment with a slow-releasing oxytocin preparation at the onset of oestrus on the ovulation rate of Merino ewes.
abstract: The effect of a slow-releasing oxytocin preparation on the ovulation rate of Merino ewes was investigated. Synchronised Merino ewes were subcutaneously injected with a slow-releasing preparation containing 10 IU oxytocin, 48 hours after sponge withdrawal. Laparoscopic examination of the ovaries of all ewes was performed 10 d after the oxytocin treatment in order to determine the number of corpora lutea per ewe. The ovulation rate of the adult ewes of the treated and control groups was 179.1% and 159.1% respectively (p < 0.05) while that of the 2-tooth ewes was 108.3% and 112.8% respectively (p > 0.05). It would appear that a higher ovulation rate can be obtained by a single injection of a slow-releasing oxytocin preparation at the onset of oestrus. The lack of response in the 2-tooth ewes was probably due to their relatively low body weight.
authors.affiliation: Grootfontein Agricultural Development Institute, Middelburg, South Africa.
authors.forename: P R
authors.initials: PR
authors.lastname: King
authors.forename: W A
authors.initials: WA
authors.lastname: Coetzer
mesh_terms: D000818:Animals; D003692:Delayed-Action Preparations; D004971:Estrus; D005260:Female; D010060:Ovulation / Q000187:drug effects*; D010062:Ovulation Induction / Q000379:methods / Q000662:veterinary*; D010121:Oxytocin / Q000008:administration & dosage*; D012756:Sheep / Q000502:physiology*
chemical_list: D003692:Delayed-Action Preparations; D010121:Oxytocin