Reproductive biology and artificial insemination of addax (Addax nasomaculatus) in captivity

Abstract

Basic information on the reproduction of female addax in captivity, the reproductive parameters of captive, male addax, the feasibility of storing addax semen at -196°C, the regulation of ovulation and the use of frozen, thawed semen in the artificial insemination (AI) of addax in captivity was obtained during this research. Mortality statistics for captive addax and hematologic and serum chemistry values from four immobilized, male addax were also presented, but not discussed. Records from 27 zoological gardens were collated to provide data on the reproduction of female addax. The age at which female addax became fertile ranged from 1.4-2.2 yr. Approximately 50% of females had their first calf in February, March or April. Subsequent births were randomly distributed throughout the year. The mean [plus or minus] STD interbirth interval was 356 [plus or minus] 105 d with 33.7% of the intervals being 9 mon in length. Urine samples collected from two female addax failed to provide information on the estrous cycle. Four male addax of various ages were immobilized and electroejaculated every 4 wk for 1 yr to obtain data on male reproductive parameters. An average ejaculate contained a total of 704.6 x 10^6 sperm, 60% normal sperm and 5% immature sperm in 1.57 ml. The following parameters were also studied: scrotal diameter, scrotal volume, testosterone, luteinizing hormone, estradiol, semen pH and semen osmolarity. No consistent changes related to season were observed in any parameter. Significant correlations were found between the total number of sperm and LH and between testosterone and scrotal volume. Age related changes were observed in the percent normal sperm, the percent immature sperm, scrotal diameter and scrotal volume of one male during the study. Addax spermatozoa were similar in size and structure to other bovid spermatozoa. The ability of lactose, tris and raffinose base extenders to protect addax sperm during freezing and thawing was evaluated in vitro using the zona-free hamster ova penetration test, the Syva Penetrak test and time-exposure dark-field photography. Fifteen semen samples, which ranged in post-thaw motility from 1-80%, were evaluated in each test...