Urinary steroid evaluations to monitor ovarian function in exotic ungulates: III. Estrone sulfate and pregnanediol‐3‐glucuronide excretion in the Indian rhinoceros (Rhinoceros unicornis)

Abstract

A study was undertaken to identify urinary estrogen and progesterone metabolites in the female Indian rhinoceros (Rhinoceros unicornis). Measurements of these metabolites were then used to monitor ovarian function and establish normal levels and patterns of steroid excretion during the estrous cycle and pregnancy. Urine samples were analyzed for estrone sulfate and pregnanediol-3-glucuronide (PDG) by direct radioimmunoassays. Both hormones produced discrete profiles reflecting ovarian activity in nonconceptive cycles. The estrous cycle was observed to be 48 days (range 39-64) with a mean follicular phase of 14.8 days (range 13-19), followed by a mean luteal phase of 19 days (range 17-21). Of the single gestation monitored, PDG levels rose above luteal phase levels by the third month after breeding and remained elevated throughout gestation. The combined estrogen and progesterone metabolite profiles present a complete evaluation of ovarian steriod production in the mature female Indian rhinoceros.

Measurement of urinary oestrogens and 20 -dihydroprogesterone during ovarian cycles of black (Diceros bicornis) and white (Ceratotherium simum) rhinoceroses

“…marmosets (Hodges & Eastman, 1984), but is not thought to be important in ungulates (Mellin el al., 1965). Conjugated oestrone is the major urinary oestrogen in the majority of ungulate species (Lasley, 1985;Lasley et al, 1989) including other perrisodactyls, the horse (Hillman & Loy, 1975), tapir (Kasman et al, 1985) and Indian rhinoceros (Kassam & Lasley, 1981;Kasman et al, 1986). Oestrone was excreted mainly as a glucuronide in black rhinoceroses, as also described by Ramsay et al (1987), and concentrations of hydrolysed urinary oestrone conjugates correlated well with reproductive events.…”

“…Mean concentrations of urinary oestrone rose 5 days before oestrus in the black rhinoceros, when 20a-DHP declined, to reach peak concentrations on the day of oestrus. The only other data on the pattern of urinary oestrogen excretion in rhinoceroses were obtained by Kassam & Lasley (1981) and Kasman et al (1986) for the Indian species, in which concentrations were generally much higher, with a more protracted increase during the pre-ovulatory period.…”

“…As in most ungulates investigated (Loskutoff et al, 1983;Hodges & Green, 1989; Hodges, 1990), the Indian rhinoceros excretes pregnanediol-3a-glucuronide (PdG) as the major progesterone metabolite in the urine (Kasman et al, 1986;Hindle et ai, 1988). The most abundant urinary oestrogen is conjugated oestrone, predominantly oestrone sulphate (Kassam & Lasley, 1986;Kasman et al, 1987), and measurement of these metabolites has provided a method for monitoring the ovarian cycle and pregnancy in this species.…”

Follicular, endocrine and behavioural dynamics of the Indian rhinoceros (Rhinoceros unicornis) oestrous cycle

“…Both urinary and faecal hormone metabolite data matched to observations of behavioural oestrus have been used to monitor reproductive cyclicity in the Indian rhinoceros (Kassam & Lasley 1981, Kasman et al 1986, Hodges & Green 1989, Schwarzenberger et al 2000. These studies documented significant variability in the duration of the ovarian cycle, ranging from 39 to 64 days (Kassam & Lasley 1981, Kasman et al 1986, Schwarzenberger et al 2000.…”

“…These studies documented significant variability in the duration of the ovarian cycle, ranging from 39 to 64 days (Kassam & Lasley 1981, Kasman et al 1986, Schwarzenberger et al 2000. However, none of these studies incorporated ultrasonography in the methodologies employed.…”