A preliminary study of reproductive physiology of captive Himalayan tahr (Hemitragus jemlahicus)

Abstract

The present study was an attempt to monitor basic reproductive parameters i.e. reproductive season, oestrous cycle and length of gestation of Himalayan tahr (Hemitragus jemlahicus) in captive conditions.

An experiment was designed to monitor time of mating and serum progesterone concentration in females and testosterone in males during the May and June time when mating activity occurred in the wild. Surprisingly, breeding activity was not recorded during the year of this study.

Testosterone secretion profiles of males peaked in May, coincident with the maximum testicular diameter. However there was no sign of any breeding activity and ovarian activity of the females, as judged by the increment in plasma progesterone concentration, did not start until early July.

The effect of stress on reproductive axis of tahr was investigated in a second experiment by challenging the animals with an injection of ACTH. This had no effect on plasma progesterone concentration in females but there was a progesterone response in males, possibly from an adrenal source. It was not possible to deduce from this whether stress might have a direct effect on reproductive activity in female tahr, so the mechanism of interruption of breeding activity in this study could not be resolved.

A third experiment was carried out to determine the pattern of progesterone secretion following super ovulation, six non-pregnant tahr were treated with exogenous progesterone (intravaginal CIDRs) for 12 days during October 1989 and injected i.m. with 1000 i.u. of PMSG 24 h prior to CIDR withdrawal. Mean (± s.e.m.) plasma progesterone concentration was low (0.48 ± 0.05 ng.ml⁻¹) for 3 days following CIDR withdrawal, then increased and remained elevated (3.84 ± 0.31 ng.ml⁻¹) for the remainder of the sampling period. These results showed that artificial induction of ovulation can cause synchronous ovulation in tahr. The corpus luteum formed after this induction was still active on day 20, indicating that its life span is similar to that of the nanny goat.