Lifetime semen production in a cheetah (Acinonyx jubatus)

Abstract

Lifetime semen production data provide valuable insight into a species' natural history and biology as well as information about the potential fertility of males at various life stages. An understanding of the ages of sexual maturity, peak sperm production, and gonadal senescence will contribute to the design of species management plans for captive, free-ranging, and reintroduced populations of exotic animals. To describe these life stages in the cheetah, semen was collected biweekly for 13 years from a solitary male beginning at 3 years of age. The 338 ejaculates were obtained noninvasively by artificial vagina. Ejaculate volume and sperm motility score, concentration, and normal morphology were recorded. A sperm quality index incorporating all five semen parameters was calculated to facilitate ejaculate comparisons. Polynomial regression analysis revealed a significant effect of age on volume, which increased throughout the animal's lifetime except for a reduction between ages 10 and 12. Concentration was also significantly affected by age and increased from the age of 3 to the age of 10, then decreased. The sperm quality index revealed a significant effect of age as it increased from age 3 to age 8, then declined as the male grew older. The cheetah did not reach peak semen production until age 8 and continued to produce good quality semen for several more years. These data were somewhat unexpected, given the average cheetah life expectancy of approximately 7 years.

Increasing Age Influences Uterine Integrity, But Not Ovarian Function or Oocyte Quality, in the Cheetah (Acinonyx jubatus)1

“…Our strategy also was bolstered by having significant biological information regarding the cheetah, probably the most studied ''wild'' animal in the reproductive sciences [4]. Besides extensive physiological data on sperm form and function [40,41,50,51] and endocrine patterns (gonadal [9,10] and adrenal [10,52,53]), substantial data exist regarding ovarian morphology, activity, and sensitivity to exogenous gonadotropins [11][12][13]. Because the cheetah is an induced ovulator [9], and due to inexplicable and often protracted intervals of ovarian quiescence [9], the ovary of this species generally responds well and consistently to the eCG/hCG regimen used in the present study [12,13].…”

Senescent sperm performance in old male birds

“…Laboratory studies of a few individuals of black‐footed ferret Mustela nigripes and cheetah Acinonyx jubatus showed that sperm production, sperm motility and the proportion of normal sperm all declined in males at old age (Wolf et al. , 2000; Durrant et al. , 2001).…”

“…Laboratory selection experiments on Drosophila melanogaster have demonstrated senescent decline in sperm performance (Service & Fales, 1993). Laboratory studies of a few individuals of black-footed ferret Mustela nigripes and cheetah Acinonyx jubatus showed that sperm production, sperm motility and the proportion of normal sperm all declined in males at old age (Wolf et al, 2000;Durrant et al, 2001). Much more extensive studies of humans have shown increased frequency of double-strand DNA breaks with age (Singh et al, 2003).…”

Ejaculate traits in the Namibian cheetah (Acinonyx jubatus): influence of age, season and captivity

“…Approximately 70% of cheetah cubs are born on Namibian farmlands from March through July (Marker et al 2003a), and given a gestation of 94 days (Brown et al 1996), we can extrapolate to a breeding season of December through April for this geographic region. In terms of impact of a captive environment, zoo-maintained cheetahs produce spermatozoa throughout the year Durrant et al 2001). Interestingly, Wildt and colleagues found similar seminal quality for cheetahs in North American zoos, in one captive facility in South Africa as well as from a small cohort of free-living males in Tanzania (Wildt et al , 19876, 1993.…”