Effect of castration on plasma concentrations of luteinizing hormone and follicle-stimulating hormone in adult Merino rams which were homozygous carriers or non-carriers of the Booroola fecundity gene

摘要

Summary. Before castration, the mean plasma concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) did not differ between FF and ++ Booroola rams. After castration, mean LH and FSH concentrations increased after 8 h, and for the next 14 days the rate of increase in FSH, but not LH, secretion was significantly faster in FF than in ++ rams (P < 0·05). Mean FSH concentrations over this period were significantly higher in FF than in ++ rams (P < 0·05). In both genotypes, the ranked FSH values did not significantly change their order over time, i.e. a significant within-ram effect was noted (P < 0·05). Repeated-measures analysis of variance indicated a significant effect of genotype on mean FSH secretion (P < 0·05) and a significant effect of sire in the FF (P < 0·05), but not the ++ (P = 0·76), genotype. From Day 28 to Day 58 after castration, FSH and LH concentrations were variable and no overall increases in concentrations were observed. The mean concentrations of both hormones over this period were not related to genotype.