Effect of testosterone and bovine follicular fluid on concentrations of luteinizing hormone and follicle-stimulating hormone in plasma of castrated rams that are homozygous carriers or non-carriers of the Booroola fecundity gene

摘要

Summary. Castrated adult FecB FecB and Fec+ Fec+ Booroola rams were injected with charcoal-treated bovine follicular fluid (bFF) (a source of inhibin-like activity) or given testosterone implants to examine whether the fecundity gene (FecB) influences sensitivity to negative feedback hormones in males. Mean concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) did not differ between genotypes before treatment. In Expt 1, injections of 5 ml bFF, but not of 1 ml (each given four times at intervals of 8 h), significantly (P < 0·05) depressed concentrations of LH and FSH, but there was no effect of genotype. After treatment, gonadotrophin concentrations returned to pretreatment values and for 2–2·5 days scaled (divided by pretreatment mean) LH values (235 ± 49 for FecB FecB and 96 ± 26% for Fec+ Fec+ rams; P < 0·05) and scaled FSH values (106 ± 5 for FecB FecB and 85 ± 5% for Fec+ Fec+ rams; P < 0·05) were significantly higher in FecB FecB than in Fec+ Fec+ rams in the group that received 5 ml bFF. Irrespective of genotype, treatment with 5 ml bFF did not reduce mean FSH to concentrations observed in testis-intact rams.