Effect of charcoal-treated bovine follicular fluid on the secretion of FSH in ovariectomized and intact prepubertal heifers *

harcoal-extracted bovine follicular fluid (bFF) has been shown to suppress FSH but not LH concentration when administered to ovariectomized 6,8 and intact 10,12,16,17 heifers. In intact heifers, however, several reports 7,14 were unable to detect a significant bFF-induced suppression of FSH. The authors suggested that the inhibin activity in the follicular fluid injections may was insufficient to decrease FSH or that blood samples were not taken frequently enough to detect a decrease in FSH. In the absence of available information concerning the optimal in-vivo model system for demonstration of bFF biological activity in cattle, the objective of this study is to determine the effect of charcoal-extracted bFF injections on circulating FSH concentrations in ovariectomized or intact prepubertal heifers.