Zoo zyxw Biology 12:97-103 (1993) Fertility Assessment of Cheetah Males With Poor Quality Semen D.G. Lindburg, B.S. Durrant, S.E. Millard, and J.E. Oosterhuis Center for the Reproduction of Endangered Species (D.G.L., B.S.D., zyxw S.E.M.), and Veterinary Services Department (J. E. O.), Zoological Society of San Diego, San Diego, California zyxwvuts Reports on semen quality of the cheetah (Acinonyx zyxwv jubutus) indicate that high percentages of abnormal morphs and sperm concentrations, 10 times lower than in domestic cats, are found in all populations. These characteristics are believed to result from unusual genetic homozygosity zyxwv , hypothesized to have been caused by passage of the species through one or more population bottlenecks during its recent history. In a sample of 12 captive-living males, we found semen charac- teristics to be equal or inferior to those previously reported for males living in other captive facilities. Ten of these males (83.3%) nevertheless produced preg- nancies. Seventeen of 19 pregnancies resulted from matings during a single es- trus. This examination of the reproductive potential of males having compara- tively inferior ejaculate quality supports the suggestion that husbandry programs may be more significant than physiological impairment in causing the low birth rates of captive cheetahs. These results also have implications for ascertaining fertility thresholds in mammalian populations undergoing increased levels of in- breeding as a consequence of habitat deterioration. zyxw 0 1993 Wiley-Liss, Inc. Key words: Acinonyx jubatus, reproduction, husbandry, inbreeding, mammal INTRODUCTION Inbreeding has been shown to have deleterious effects on reproduction in a wide range of species, including laboratory mice, domestic livestock, and zoo exotics [Johansson and Rendel, 1968; Ralls et al., 1979; Green and Witham, 19911. From electrophoretic surveys of 128 individuals, the cheetah zyx (Acinonyx jubatus) has been shown to exhibit less than 5% heterozygosity at 52 protein loci, a level of genetic uniformity similar to that found in inbred mice [O’Brien et al., 1983, 1985, 1987al. Acceptance of skin allografts in unrelated pairs of cheetahs has been interpreted as Received for publication August 3, 1992; accepted October 26, 1992. The review process for this article was carried out by zyxwv Dr. Michael J. Raleigh, editor of American Journal of Primatology. Address reprint requests to Dr. Donald G. Lindburg, Zoological Society of San Diego, P.O. Box 551, San Diego, CA 92112. zyxwvuts 0 1993 Wiley-Liss, Inc.