CGN assists in sperm extraction of ring-tailed vontsira

March 21, 2024

The Centre for Genetic Resources, the Netherlands (CGN) was requested by the European Association of Zoos and Aquaria (EAZA) to attempt to collect and freeze sperm of a ring-tailed vontsira (Galidia elegans).

Ring-tailed vontsiras are small predators, native to Madagascar. Although according to the IUCN Red List it does not currently fall within the CR (critically endangered) or EN ( endangered) categories, its population in the wild has been declining for years on end, partly due to habitat loss. To ensure sustainable conservation of the ring-tailed vontsira and other endangered zoo animals, the EAZA has enlisted the help of the CGN at Wageningen University & Research.

Spanish veterinarian Isabel Callealta came specially to the Zie-ZOO zoo in Volkel to perform a fertility check on one male and two females. For this, sperm was taken from the male using a very thin catheter. Primarily to check whether he was producing healthy sperm cells, but possibly also to freeze some of the sperm cells so that they could be used for insemination later.

Echo for monitoring
Echo for monitoring

Freezing sperm doses

Agnes de Wit, researcher at the CGN, was present during the procedure and took care of freezing the samples. "Although Isabel managed to collect some semen from the male, the concentration and motility (the number of active sperm cells per millilitre of semen) was very low. After Isabel collected the samples for the fertility check, I mixed the remaining part of the sperm (two doses of 0.25 ml) with a cryoconservation medium and froze two straws."

To freeze the samples, Agnes used the so-called 'floating rack' method, where the straws are placed on a rack floating on liquid nitrogen: "After a few minutes, the straws are frozen, after which they can be stored in liquid nitrogen."

Container of liquid nitrogen to hold the straws
Container of liquid nitrogen to hold the straws

No insemination doses, yet positive result

Despite the careful execution of this procedure, after thawing one of the straws, it turned out that the frozen sperm is probably not viable for regular insemination: "The concentration was too low for that." But there is also good news: "Although these straws cannot be used for insemination, it seems that the sperm can indeed be frozen in this way. And that is valuable information for future freezing attempts."