Collection and short-term preservation of semen from free-ranging eastern grey kangaroos (Macropus giganteus: Macropodidae)

Objectives To evaluate electro-ejaculatian of free-range eastern grey kangaroos in the field and assess the efficacy of four diluents to preserve sperm motility over a 48-h period at 5 degrees C. Procedure and design Under gaseous anaesthesia, 25 free-range kangaroos were electro-ejaculated and characteristics of the ejaculate noted. Spermatozoa obtained from eight ejaculates were diluted in phosphate buffered saline containing various combinations of egg yolk and glucose and refrigerated al 5 degrees C for 48 h. Results Spermatozoa were recovered from 24 of 28 ejaculates. Mean (+/- SEM) semen volume (mt) and pH were 25.0 +/- 1.9 and 7.1 +/- 0.1 respectively. The forward motility (%), rate of movement of sperm (0 to 5) and sperm concentration (x 10(6)/mL) were 77.4 +/- 1.5, 3.8 +/- 0.9 and 31.2 +/- 7.3 respectively. There was no significant difference between the four diluents in their ability to maintain forward motility of spermatozoa over 48 h. However, rate of movement. over the same period was significantly (P < 0.01) improved when sperm were diluted in phosphate buffered saline containing 10% egg yolk. Conclusions Electro-ejaculation is a safe and reliable method for collecting semen from free-ranging eastern grey kangaroos. Preliminary attempts at short-term preservation showed that the motility of kangaroo spermatozoa could be adequately stored for 24 h and that the addition of egg yolk to the semen diluent was beneficial for improving the rate of sperm movement.