Elephants Elephants - Wildpro - Twycross Zoo

eadily available and the results take two to three days. The best method at
present, to predict ovulation, is an ultrasound examination of the ovaries.
Hormone analysis can be used to diagnose pregnancy and predict date of
birth, and by analysing prolactin levels from blood (Brown 2000), which
increases after about 20 weeks of gestation. Current methods, measuring
progestins from urine can diagnose pregnancy after about week 12. Recent
work suggests that, at least in Asian elephants, a change in the 17αhydroxyprogesterone
(OHP): progesterone ratio occurs as soon as 2-7 weeks
after conception. Maternal testosterone levels in females are higher when
carrying a male calf. There is a decrease in progestogens two to five days
preceding birth allowing for reasonably accurate prediction. Lactation
anoestrus has been found to last about 46 weeks. If the mother, for a variety
of reasons, does not suckle the calf after birth the period can be as short as
eight weeks.
Measurement of testosterone levels in bulls gives an indication of testicular
function. Dominant males exhibit higher testosterone levels that subordinates.
This work may prove important in investigations on bulls with low libido or
with poor sperm ejaculates. Monitoring of a combination of conditions, from
plasma testosterone, testes and accessory gland development, and ejaculate
have provided good background information in being able to assess the
reproductive potential of bulls at an early stage (Fritsch et al 2001).
Recent work (Duer et al 2002) has shown that foetal testes produce
testosterone early in gestation. This can be detected in maternal serum levels
in the second and last third of gestation, allowing the collection to know if a
male or female calf is expected.
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