Artificial Insemination

Feeding a 2 days old infant

A 5 day old infant

A 3 day old infant

Before each feeding the infant was stimulated to defecate and urinate

A one month old infant

A 20 day old infant

A 40 day old infant

Artificial insemination has produces only three litters outside China up to 1990. This is surprising a low rate of success, for in theory at least the technique is not difficult. The male is anaesthetized, and in an undignified but painless operation, an electrode is inserted into the animal’s rectum. A series of up to six brief shocks (less than 6 volts) is passed through the electrode to achieve erection. The electrode is then withdrawn slightly and the train of shocks repeated to stimulate ejaculation. The semen collected can then be checked for signs of infertility, and either used immediately or stored in liquid nitrogen.

The operation to inseminate the female is only slightly more difficult. The female is anaesthetized, and the semen introduced into the vagina using a catheter, the only real challenge being to guide the catheter past the obstructing ridges of the vaginal wall so that the semen can be deposited at the entrance to the cervix. In some species, the success of artificial insemination has been improved by injecting the semen directly into the uterus, but so far this has only occasionally been possible in the panda because the entrance to the cervix is very narrow. New equipment allow semen to be introduced deep into the cervical canal or even into the uterus itself, but it is unlikely that this alone will make very much difference to the success rate of artificial fertilization because the main difficulties associated with the technique lie elsewhere.

In captivity, without the presence of a male, there is no external sign of a female giant panda which clearly signals that the peak oestrus has actually arrived, and that the female has ovulated and could be fertilized. Consequently, the timing of artificial insemination was largely a matter of educated guesswork until a technique could be developed to determine the changes in hormone levels in the animal’s urine.

The development of the technique of urinalysis and its subsequent refinement has allowed researchers to carry out artificial insemination with much greater confidence in 1984. During the period leading up to oestrus, the urinary level of oestrogens increases steadily. This triggers a surge in luteinising hormone which in turn stimulates rupture of the ovarian follicle and release of the egg. If a female is housed with a male, the peak period of sexual interaction occurs immediately after the peak in oestrogen levels is reached, and the fall in oestrogen levels in the urine is therefore the most reliable guide to the timing of artificial insemination.

Even with the help of hormone assays, veterinarians still seem to be much less efficient than male pandas at fertilizing females, and only time will tell whether this is due to lack of experience or a consequence of the panda’s physiology. It is not impossible that the interaction of male and female before ovulation might affect the female’s hormone levels in a way that facilitates fertilization.