Puberty in the male Nubian Goat: Serum concentrations of LH, FSH and testosterone from birth through puberty and semen characteristics at sexual maturity

Abstract

Changes in serum hormone concentrations and the onset of puberty were studied in a group of eight male Nubian goats from birth through 44 weeks of age. Onset of puberty was defined as the age at which an ejaculate containing motile spermatozoa was first collected by electroejaculation. Sexual maturity was reached at a mean age of 32.4 ± 0.9 weeks at an average body weight of 37.7 ± 3.3 kg. Mean ejaculate volume and sperm concentration at puberty were 0.92 ± 0.07 ml and 1.25 ± 0.37 × 10 9/ml of ejaculate, respectively. Serum luteinizing hormone (LH) concentrations were elevated between birth and 20 weeks of age, and then declined coincidently with an increase in serum testosterone concentration; LH levels thereafter remained low through 44 weeks of age. The temporal pattern of serum follicle stimulating hormone (FSH) secretion during this period was similar to that of LH, except after declining to a low concentration immediately postpuberty, FSH concentrations increased again to early prepubertal levels. Serum testosterone concentrations were low for the first 20 weeks of age, increased to peak levels at the time of puberty and then declined to adult levels. There was evidence of at least one LH pulse/3 h during the prepubertal period. These data indicate that a decline in serum LH follows an elevation in serum testosterone and suggests negative steroid feedback effects. Additionally, it appears that testosterone is probably an important regulator of sperm maturation and the onset of puberty in the male goat.