Effect of Unilateral Ovariectomy and Injection of Bovine Follicular Fluid on Gonadotropin Secretion and Compensatory Ovarian Hypertrophy in Prepuberal Heifers

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Abstract
A study was conducted to determine whether compensatory ovarian hypertrophy occurred in prepuberal heifers, and if so, could compensatory ovarian hypertrophy be prevented by injecting charcoal-extracted bovine follicular fluid (CFF). An additional objective was to determine the effect of CFF injections on follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations following unilateral ovariectomy (ULO). Thirty-one prepuberal Angus, Hereford, and Angus × Hereford heifers were assigned by weight and breed to the following groups: Control-saline injections (C), unilateral ovariectomy-saline injections (ULO) and unilateral ovariectomy-CFF injections (ULO-CFF). In group C, a sham operation was performed on d 0 and both ovaries were removed on d 7. In groups ULO and ULO-CFF, either the right or left ovary was removed on d 0 and the remaining ovary was removed on d 7. From d 0 to 7, each heifer received an injection (iv, 7 ml/injection) of saline or CFF every 12 h. Jugular blood samples were collected immediately before each saline injection from d 0 to 7 and analyzed for FSH and LH. Unilateral ovariectomy increased ovarian (P<.08) and follicular fluid (P<.05) weights compared with groups C and ULO-CFF; however, lyophilized ovarian weight was similar (P>.05) for all groups. Injections of CFF blocked the increase in ovarian and follicular fluid weight following ULO. The total number of visible follicles per ovary was similar for all groups; however in the ULO group there was an increase (P<.01) in those 5 to 6 mm and ⩾9 mm. This shift in follicle population to a larger size was blocked by CFF. By 24 h after ULO there was a transient increase (P<.05) in circulating concentrations of FSH in the ULO group, but not in the ULO-CFF group. There was no difference (P>.05) over time in the circulating LH concentrations among the three groups. These results indicate that compensatory ovarian hypertrophy in prepuberal heifers is accompanied by a selective, transient rise in FSH and administration of charcoal-extracted CFF prevents both the FSH rise and compensatory ovarian hypertrophy. Copyright © 1985. American Society of Animal Science . Copyright 1985 by American Society of Animal Science