Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-03T05:25:57.265Z Has data issue: false hasContentIssue false
  • English
  • Français

The induction of coincident superovulation and oestrus in the anoestrous ewe

Published online by Cambridge University Press:  27 March 2009

G. L. Hunter ,
G. P. Bishop  and
D. L. Brown
G. L. Hunter
Affiliation:
University of Natal, Pietermaritzburg, South Africa
G. P. Bishop
Affiliation:
University of Natal, Pietermaritzburg, South Africa
D. L. Brown
Affiliation:
University of Natal, Pietermaritzburg, South Africa
Get access Rights & Permissions [Opens in a new window]

Extract

Eight Merino and eight Dormer ewes, none of which had been on heat for 2–3 months prior to treatment, were given six intra-muscular injections of 30 mg. progesterone at 3-day intervals. The ewes were divided into four groups, each consisting of two Merinos and two Dormers. On the second day after the last progesterone injection, 1000 i.u. P.M.S. were administered to each of the ewes in group I. The remaining ewes each received an injection of 500 i.u. P.M.S. on either the first and second days (group II), the second and third days (group III), or the first and third days after the end of the progesterone treatment (group IV).

Five of the Dormer ewes, but not one of the Merino ewes, were served after the treatment. Mean ovulation rates for the four groups were 2·50, 2·75, 2·00 and 2·50, respectively, and the mean numbers of large follicles (i.e. those which were observed at laparotomy, approximately a week after treatment, to have a diameter of not less than 4 mm.) were 3·00, 2·75, 1·00 and 2·00, respectively. Contrary to expectation, it was observed that only one of the ewes (a Merino) showed evidence of a silent ovulation shortly before treatment.

It is suggested that (i) the amount of oestrogen produced by the ovarian follicles of the Merinos may have been exceptionally low, thus accounting for the non-occurrence of oestrus in these ewes, (ii) ovulation rates might be increased by greater reductions in the time between the last progesterone injection and P.M.S. treatment, and (iii) if silent heat in the Merino is rare, it may be simpler to induce coincident heat and superovulation in ewes of this breed by two injections of P.M.S. at 16-day intervals.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 51 , Issue 2 , October 1958 , pp. 129 - 132
Copyright
Copyright © Cambridge University Press 1958

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Averill, R. L. W., Adams, C. E. & Rowson, L. E. A. (1955). Nature, Lond., 176, 167.CrossRefGoogle Scholar
Cole, H. H. & Miller, R. F. (1933). Amer. J. Physiol. 104, 165.CrossRefGoogle Scholar
Dutt, R. H. (1953). J. Anim. Sci. 12, 515.CrossRefGoogle Scholar
Hafez, E. S. E. (1952). J. Agric. Sci. 42, 189.CrossRefGoogle Scholar
Hunter, G. L. (1954). J. Endocrin. 10, xiii.Google Scholar
Hunter, G. L., Adams, C. E. & Rowson, L. E. A. (1955). J. Agric. Sci. 46, 143.CrossRefGoogle Scholar
Hunter, G. L. (1956). Unpublished data.Google Scholar
Robinson, T. J. (1951). J. Agric. Sci. 41, 6.CrossRefGoogle Scholar
Robinson, T. J. (1954 a). J. Endocrin. 10, 117.CrossRefGoogle Scholar
Robinson, T. J. (1954 b). Endocrinology, 55, 403.Google Scholar