Characteristics of koala (Phascolarctos cinereus adustus) semen collected by artificial vagina

Abstract

Collection of semen using a modified ovine artificial vagina was attempted on 90 occasions from 25 Queensland koalas (Phascolarctos cinereus adustus). Complete ejaculates consisting of a copulatory plug and sperm fraction were collected on 36 occasions (40%) from 19 animals. Seventeen of the males produced a complete ejaculate on their first or second service. Failure to collect semen (38%) and the collection of partial ejaculates (14.5%) was attributed to lack of sexual interest, aggressive behaviour towards the female by the male, the use of non-compliant teaser females or a distinct dislike of the artificial vagina. Only a few ejaculates were contaminated with urine (4.5%) or obtained after ejaculation behaviour was terminated (3%). The mean (± SEM) values for the seminal characteristics of 19 complete ejaculates were: mass of copulatory plug fraction 0.78 ± 0.10 g, sperm fraction volume 0.73 ± 0.10 ml, sperm concentration 165.1 ± 26.7 x 106 ml-1, pH of sperm fraction 6.7 ± 0.2, osmolarity of sperm fraction 315.0 ± 5.4 mOsm, percentage forward motility 70.7 ± 1.8%, rate of sperm movement 4.0 ± 0.1 and percentage of abnormal spermatozoa 26.9 ± 2.5%. Percentages of sperm head morphotypes and tail abnormalities were documented. Although the artificial vagina technique is limited by the need for access to oestrous females, the procedure described has been shown to be a simple, reliable method of collecting semen from captive koalas.