Testosterone and LH concentrations in the male Angora goat during puberty

Abstract

Fifteen Angora male kids were used in order to investigate long-term reproductive endocrine changes associated with testis size, liveweight and season in a study of puberty and duration of the first breeding season. Blood samples were collected at weekly intervals; testis size and liveweight were recorded at 2-week intervals from post-weaning through puberty. With respect to the testosterone and LH concentrations and testis and body growth rates, that is, onset of puberty, two different groups of kids were distinguished (groups A and B). Testosterone and LH levels were significantly higher ( P<0.01) in group A than in group B during the breeding season, as were testis size and body weight, reflecting that group A animals reached puberty earlier (∼ 178 ± 12 days of age). The high levels of testosterone (4.09±1.78 ng/ml) found in autumn were evidently a result of increased testicular steroidogenic activity (testicular responsiveness to LH). The elevation in testosterone and LH levels was accompanied by decreasing daylength and temperature, and increasing humidity. It thus appears that in male kids the onset of puberty and sexual maturation are individually variable.