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New Zealand Journal ofAgricultural ResearchPublication details, including instructions forauthors and subscription information:http://www.tandfonline.com/loi/tnza20

An attempt to use oestrogeninjections to induce ovulationin anoestrous New ZealandRomney ewesR.A.S. Welch aa Ruakura Agricultural Research Centre , P.B.,Hamilton , New ZealandPublished online: 12 Jan 2012.

To cite this article: R.A.S. Welch (1970) An attempt to use oestrogen injections toinduce ovulation in anoestrous New Zealand Romney ewes, New Zealand Journal ofAgricultural Research, 13:3, 660-661, DOI: 10.1080/00288233.1970.10421611

To link to this article: http://dx.doi.org/10.1080/00288233.1970.10421611

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AN ATTEMPT TO USE OESTROGEN INJECTIONSTO INDUCE OVULATION IN ANOESTROUS

NEW ZEALAND ROMNEY EWES

By R. A. S. WELCH*

(Received 6 January 1970)

ABSTRACT

Intramuscular oestrogen injection of New Zealand Romney ewesduring their anoestrous period failed to establish the efficacy of thismethod alone in inducing ,ovulation.

INTRODUCTION

Difficulty has been found in inducing ovulation during the anoes­trous period in New Zealand Romney ewes by means of progesteroneinjections followed by gonadotrophins (Welch 1969).

The injection of 10-50 p,g of oestradiol into anoestrous ewes willproduce an increased concentration of LH in the blood 10-20 hr lateras measured by radioimmuno-assays (Blackey, Brown, Catt, Cumming,and Goding 1970; Radford, Wallace, and Wheatley 1970). This increasein LH concentration is similar to the LH surge that precedes ovulationin the cycling animal (Geschwind and Dewey 1968; Niswender, Roche,Foster, and Midgley 1968; Goding, Catt, Brown, Kaltenbach, Cumming,and Mole 1969; Wheatley and Radford 1969). An injection of oestro­gen will produce ovulation in anoestrous Merino ewes (Radford, pers.comm.). The method was tested for its ability to induce ovulation inanoestrous New Zealand Romney ewes.

Experimental

Nine mature New Zealand Romney ewes were injected intramus­cularly with 40 p,g oestradiol 17-f3 in oil on 13 October 1969. Theanoestrum for this breed in New Zealand is from about mid August toabout mid February. The LH surge follows within 20 hr of the oestro­gen injection and ovulation occurs about 24 hr after HCG injection(Hinds, Dzuik, and Lewis 1964) and presumably at that time after anLH surge. Hence any ovulation in response to the oestrogen injectionwould be expected to occur within 3 days.

Accordingly the sheep were laparotomised 3 days after injectionand their ovaries inspected.

* Ruakura Agricultural Research Centre, P.B., Hamilton, New Zealand.

N.Z. Jl agric. Res. (1970), 13: 660-1

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R. A. S. WELCH 661

Results

One of the 9 treated ewes had a recent ovulation. No lutealtissue was observed on the ovaries of the other ewes. There wereGraafian follicles on each ovary. These were all 5 mm or less indiameter and not considered to show signs of impending ovulationaccording to the criteria of Restall (1961).

These data indicate that an oestrogen injection alone is not a goodmethod for the induction of ovulation in anoestrous New ZealandRomney ewes.

REFERENCES

BLOCKEY, M. A; BROWN, J. M.; CAIT, K. J.; CUMMING, I. A; GODING,I. A; GODING, J. R. 1970: J. Reprod. Fert. (in press).

GESCHWIND, I. I.; DEWEY, R. 1968: Proc. Soc. expo Bioi. Med. 129:451-5.

GODING, J. R.; CAIT, K. J.; BROWN, J. M.; KALTENBACH, C. C.; CUM­MING, I. A.; MOLE, B. J. 1969: Endocrinology 85: 133-42.

HINDS, F. c.; DZUIK, P. J.; LEWIS, J. M. 1964: J. Anim. Sci. 23:782-6.

NISWENDER, G. D.; ROCHE, J. F.; FOSTER, D. R.; MIDGLEY, A R.1968: Proc. Soc. expo Bioi. Med. 129: 901--4.

RADFORD, H. M.; WALLACE, A L.; WHEATLEY, I. 1970: J. Reprod.Fert. (in press).

RESTALL, B. J. 1961: Proceedings of a conference on artificial breedingof sheep in Australia. University of N.S.W. pp. 67-75.

WELCH, R. A. S. 1969: Proc. N.Z. Soc. Anim. Prod. 29: 87~94.

WHEATLEY, I.; RADFORD, H. M. 1969: J. Reprod. Fert. 19: 211-4.

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