Ovarian response to injections of charcoal-extracted porcine follicular fluid and porcine follicle-stimulating hormone in gilts fed a progesterone agonist (altrenogest)

This experiment was conducted to compare the negative effects of charcoal-extracted porcine follicular fluid (pFF) and the positive effects of purified porcine follicle-stimulating hormone (pFSH) on growth of follicles and on plasma hormone concentrations. Twenty gilts were fed altrenogest for 18 days (20 mg.day-1.gilt-1) to suppress spontaneous growth of large follicles (greater than 6 mm in diameter). Gilts, assigned at random to receive pFF and pFSH administered in a 2 x 2 factorial arrangement, were injected 9 times at 8-h intervals starting 48 h before the last feeding of altrenogest and ending 8 h before slaughter (24 h after the last feeding of altrenogest). Blood was collected periodically through vena cava catheters. Treatment groups and mean number of medium follicles (3 to 6 mm in diameter)/gilt at necropsy were 1) 20 ml of charcoal-extracted porcine serum i.v. + 4 ml saline i.m., 30.8; 2) 20 ml of pFF i.v. + saline i.m., 0.2; 3) serum i.v. + 8 micrograms of pFSH (USDA-pFSH-B1)/kg BW in saline i.m., 59.0; and 4) pFF i.v. + pFSH in saline i.m., 36.2. Injections of pFF decreased (p less than 0.01) and injections of pFSH increased the number of medium follicles, and the interaction of pFF and pFSH was not significant. Plasma FSH decreased (p less than 0.01) during pFF treatment of saline-injected gilts at a rate of 0.29 ng.ml-1.h-1. During pFSH treatment, plasma FSH increased (p less than 0.05) at statistically identical rates of 0.33 and 0.32 ng.ml-1.h-1 in serum- and pFF-injected gilts.(ABSTRACT TRUNCATED AT 250 WORDS)