Above: Philippine cockatoo: Critically Endangered and subject of a reintroduction programme

 

In the third of four articles, DR DAVID WAUGH explains how scientists are honing the technique of artificial insemination to improve the chances of successful breeding in rare parrot species – which could guarantee their future survival

HAVING assessed that a semen sample passes muster, the next step is to introduce it into a suitable female. This means a female of the same species or subspecies that is at the appropriate phase of reproductive activity, i.e. that she is releasing eggs to be fertilised.

A better prediction of egg release means waiting for the first egg to be laid before introducing the semen. This does not mean, however, that insemination prior to the laying of the first egg will not result in successful fertilisation, as these studies discovered. In this research, each insemination was performed by introducing the semen into the oviduct through a capillary tube.

In the first phase, a total of 64 inseminations were performed, which included repeated inseminations of the same female (12 cases). Fifteen samples were inseminated directly after intra-capillary examination without a detailed microscopic analysis. After AI, 25 fertile eggs were obtained out of the 36 eggs laid (69.4 per cent) by 11 females.

Altogether, fertilised eggs were produced by AI in nine species: Cacatua haematuropygia, Calyptorhynchus funereus latirostris, Ara chloroptera, Amazona pretrei, A. xantholora, A. finschi, A. viridigenalis, Tanygnathus lucionensis and Eclectus roratus polychloros.

Each successful fertilisation by AI was confirmed by DNA fingerprinting. In the case of the successful fertilisation by AI in the Philippine cockatoo (C. haematuropygia) and eclectus parrots, two inseminations for each were made only before the first egg-laying.

In a follow-up phase, five pairs of sun conures (Aratinga solstitialis) produced 23 eggs. In 13 cases AI was performed after the first egg of each clutch and the remainder after the second or third egg. This resulted in 11 fertilised eggs and eight hatched fledglings.

In eclectus parrots AI was tried six times to fertilise the second egg after the first had been laid, but without success. Then four inseminations made before the first egg was laid, resulting in four fertile eggs and three fledglings hatched. These are encouraging results which form the basis for more AI experimentation to take place.

Despite the evidence that it can be used for AI to help captive breeding, there are limitations to the use of fresh semen because it can only be stored for a short time period. This can be problematic if the female is not producing a clutch at the time of semen collection, as that is when artificial insemination must be performed. Also, during the short time period when a female is producing a clutch, there must be a fertile male available from which to collect semen.

The development of a method to store semen over the long term could provide a solution to these problems. Additionally, semen of genetically very valuable birds can be stored for a long time and multiple females located in geographically distant locations can potentially be inseminated at the same time with the same semen. This implies freezing the semen (cryopreservation) and keeping it in a sperm bank until it is thawed out for a planned future insemination.

Dr David Waugh is a former curator and current correspondent for Loro Parque Foundation.

 

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