Seasonality of Serum Testosterone Levels and Sperm Density in Tursiops truncatus.

摘要

We trained a mature male bottlenose dolphin, Tursiops truncatus, to provide semen samples on command. After completion of the 10-week training period, semen was collected twice weekly and blood was sampled twice monthly for a period of 28 months. Total sperm per ejaculate ranged from near 0 to 54.6 X 10 to the 9th power (n = 1332). Sperm densities from each session ranged from no sperm to 1,587 X 10 to the 6th power/ml (n = 241). Testosterone levels ranged from 1.1 to 54.4 ng/ml (n = 79). Seasonal variations were observed in total sperm per ejaculate, sperm density per ml of ejaculate, and in serum testosterone levels. Peak sperm densities were observed during September and October of three consecutive breeding seasons. Serum testosterone levels peaked in June, decreased during July and August, and were lowest in September and October, the period of greatest sperm density. Peak sperm production and density were coincident with the peak period of breeding activity but at a time when serum testosterone levels were lowest. Spermatogenesis, Blood-serum testosterone sampling, Reprints. (edc)