To determine whether the high ovulation rate of the Booroola Merino ewe could be explained by FSH metabolism we have tested the proposition that FSH may have a longer half-life in the plasma of Booroola Merino ewes than in control ewes. The half-life of plasma FSH was determined by removal of the pituitary gland, to abolish FSH secretion into the peripheral circulation, and monitoring by repeated blood sampling the subsequent decline in plasma FSH concentrations. The half-life of FSH was similar in Booroola (103 ± 14 (s.e.m.) min, N = 8) and control (116 ± 8 min, N = 9) ewes. However, when ewes that had been ovariectomized at least 6 months earlier were hypophysectomized, the half-life of FSH was increased from 110 + 8 min in ovary-intact ewes (N = 11) to 1101 ± 49 min (N = 6)(P<0.001) with no difference between the two Merino strains. We concluded that changes in the circulating half-life of FSH do not account for the high fecundity of the Booroola but that ovariectomy can alter the half-life of FSH by the pituitary gland.
|Number of pages||5|
|Journal||Journal of Reproduction and Fertility|
|Publication status||Published - 1 Dec 1987|