Research Note

The effect of treatment with a slow-releasing oxytocin preparation at the onset of oestrus on the ovulation rate of Merino ewes : research note

P.R. King, W.A. Coetzer
Journal of the South African Veterinary Association | Vol 68, No 1 | a859 | DOI: | © 1997 P.R. King, W.A. Coetzer | This work is licensed under CC Attribution 4.0
Submitted: 13 July 1997 | Published: 13 July 1997

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P.R. King,
W.A. Coetzer,

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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-re-leasing preparation containing 10 IU oxytocin, 48 hours after sponge withdrawal. Laparo-scopic 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.


Merino Ewes; Ovulation Rate; Oxytocin


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