Effect on ovulation rate of increasing or decreasing ovarian
exposure to follicle stimulating hormone during the preovulatory period
in ewes
K.M. Henderson, R.L. Ellen, L.C. Savage, K. Ball, K.P.
McNatty
Wallaceville Animal Research Centre, Ministry of Agriculture and
Fisheries, Upper Hutt
Proceedings of the New Zealand Society of Animal Production.
1986, 46: 157-160
Ovine FSH was administered hourly to ewes for 48 h from the
initiation of luteolysis. The mean ovulation rates of ewes receiving
2.5 µg FSH/h (2.1 ± 0.2 ovulations/ewe, mean ± s.e.m., n=8) and 5.0 µg
FSH/h (6.2 ± 2.0 ovulations/ewe, n=6) were significantly higher (P<
0.01) than that of control ewes (1.3 ± 0.1 ovulations/ewe, n=16). Mean
plasma concentrations of FSH were also raised above normal by these
doses of FSH. Plasma concentrations of FSH were reduced below normal
by twice daily administration of steroid-free bovine follicular fluid
(bFF) for 48 h from the initiation of luteolysis. As a consequence
follicles failed to achieve ovulatory maturity. Large follicles (>/=5mm
diameter) from ewes treated with bFF for 48 h had reduced concentrations
of oestradiol-17þ in follicular fluid, fewer granulosa cells, and the
cells had a reduced ability to metabolise testosterone to oestradio-17þ
and to produce cyclic AMP when challenged with FSH or LH.
Keywords: NZSAPAB;
Follicle stimulating hormone; follicular fluid; ovulation rate;
granulosal cells; sheep
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Last Updated 18-03-1997
