Depression of follicle stimulating hormone in bulls injected with follicular fluid.
Eight bulls were divided into two groups and injected with either charcoal-extracted steer blood serum or charcoal-extracted bovine follicular fluid (bFF). Ten-milliliter injections were given subcutaneous every 12 h for 4 wk. Jugular blood collected before, during and after the injection period was analyzed for follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by radioimmunoassay. All bulls were exposed to restrained, estrual heifers for 15 min every 2 wk for 16 wk starting 4 wk before the first injection. The number of mounts and services by each bull was recorded. Semen was collected with an artificial vagina and evaluated on alternate weeks during the same period. The concentration of FSH in serum decreased (P < 0.05) by 12 h after the first injection and remained 61% lower than that of serum-injected bulls during the injection period. The concentration of FSH increased (P < 0.05) by 3 d after the last injection. Injections of bFF did not affect the concentration of LH in serum. Bovine follicular fluid injections significantly depressed FSH; however, libido, serving capacity, and semen characteristics were unchanged.
McGowan
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RD
Department of Animal Sciences and Industry Kansas State University, Manhattan, KS 66506 USA.
Kiracofe
G H
GH
Bolt
D J
DJ