Interactions between dietary protein, ovulation rate and follicle stimulating hormone level in the ewe

Control of gonadotrophin release in Scottish Blackface and Finnish Landrace ewes during seasonal anoestrus

“…Finnish Landrace ewes had significantly higher (P < 001) FSH Webb, unpublished data). Also, ewes with twin lambs have higher FSH concentrations from 8 to 3 days before ovulation than do those with singletons (Davis, Brien, Findlay & Cumming, 1981). Lahlou-Kassi, Schams & Glatzel (1984) have demonstrated that FSH concentrations were higher in the prolific D'Man than in Timahdite ewes in contrast to the study of Webb & England ( 1982) using Suffolk and Finnish Landrace sheep.…”

Increase in ovulation rate after active immunization of sheep with inhibin partially purified from bovine follicular fluid

“…Previous studies have suggested that plasma FSH concentrations may influence ovulation rate in sheep (Davis, Brien, Findlay & Cumming, 1981) and, indeed, exogenous administration of FSH will increase ovula¬ tion rate in ewes (Wright, Bondioli, Grammer et al 1981). If inhibin has a physiological role in suppressing FSH production in sheep then one might have antici¬ pated that immunization against inhibin may have raised plasma FSH concentrations through inhibin antibodies effectively 'neutralizing' circulating inhibin, thereby releasing the pituitary gland from the suppressive effect of inhibin.…”

Pituitary gonadotrophins in Booroola and control Merino sheep

“…Several lines of evidence point to a role for follicle-stimulating hormone (FSH) in the mechanisms controlling follicular growth and ovulation rate in sheep. These include the effects of hypophysectomy on ovarian follicular populations (Dufour, Cahill & Mauléon, 1979) and of exogenous FSH on ovulation rate (Betteridge, 1981; Wright, Bondoli, Grammer, Kuzan & Menino, 1981), and demonstrations that plasma FSH concentrations are elevated before ovulation in sheep with increased ovulation rates induced by supplementation of the diet with lupins (Brien, Baxter, Findlay & Cumming, 1976;Davis, Brien, Cumming & Findlay, 1981; Knight, Payne & Peterson, 1981). Also, compensatory ovulation after unilateral ovariectomy is associated with a transient increase in FSH secretion (Findlay & Cumming, 1977).…”