Excretion of corticosteroids in urine and faeces of hares (Lepus europaeus).

Increased production of glucocorticoids by the adrenal cortex is found in mammals under stress. As cortisol itself is absent in the faeces, an enzyme immunoassay (11-oxoaetiocholanolone) measuring 11,17-dioxoandrostanes has already been established to measure faecal cortisol metabolites in ruminants for non-invasive monitoring of adrenocortical activity. The aim of this study was to establish route and delay of excretion of glucocorticoids in hares and to determine whether a cortisol-, corticosterone- or this new enzyme immunoassay is best suited to detect faecal glucocorticoid metabolites. In the first experiment radioactive-labelled glucocorticoids (14C-cortisol and 3H-corticosterone) were administered intravenously to two groups of three hares in metabolic cages. All voided urine and faecal samples were collected for 4 days. Metabolites of both steroids were found predominantly in the urine (91 +/- 4%). Peak concentrations were observed in the first urinary sample following infusion (13 +/- 6 h) and in the faeces with a delay of about 1 day (23 +/- 7 h). Most of the radioactivity was not extractable with diethylether, indicating that the metabolites excreted in urine and faeces are mainly conjugated or polar unconjugated ones. This was confirmed by reverse-phase high-performance liquid chromatography separations of the metabolites, which also revealed marked differences concerning the metabolism of the two glucocorticoids injected. Compared with the cortisol and the corticosterone enzyme immunoassay, only the group-specific enzyme immunoassay for 11,17-dioxoandrostanes detected high quantities of immunoreactive metabolites. In a second experiment hares (n = 20) were stressed by rousing them three times (5 min, 10 min and another 5 min) with a 20-min break in-between. Faecal samples were collected 2 days before until 4 days after stress and analysed using the 11-oxoaetiocholanolone enzyme immunoassay. After stress significantly (P < 0.001) increased 11,17-dioxoandrostane concentrations were found. Based on these results, measuring 11,17-dioxoandrostanes in faeces enables non-invasive monitoring of disturbances in hares and thus provides a tool for field investigations elucidating the role of stress in hare populations.

Effect of diet on condition indices in black-tailed jackrabbits.

Changes in blood, urine and physical condition indices in 23 adult male black-tailed jackrabbits (Lepus californicus) with ad libitum feeding and 25% feed restriction were measured over a 2 wk period from 30 May to 12 June 1988. Feed restricted jackrabbits had (1) lower post-trial body weights and kidney fat indices, (2) higher femur marrow fat, serum bilirubin and cortisol concentrations, and adrenal cortex width, and (3) depressed immune function. No single index alone could best measure the nutritional status of these jackrabbits.

Feeding and excretion in the Afghan pika (Ochotona rufescens rufescens), a new laboratory animal.

Food and water intake and the excretion of urine and faecal pellets during the day (0500-2100) and at night (2100-0500) were observed in Afghan pikas, rats and guineapigs fed appropriate diets. Urine composition was observed in these species after they had been fed the pika diet for 4 weeks. Rats ate more at night than did pikas or guineapigs. The pikas excreted numerous small, hard faeces and soft faeces, the latter being reingested. On the pika diet all species gained about 10% in bodyweight. Food consumption was similar to that shown by each species on its own diet. All animals fed the pika diet excreted alkaline urine. Chloride concentration in pika urine was similar to that of the rat and was significantly higher than that of the guineapig. The ratio of sodium to potassium in pika urine was 2.8 and 1.7 fold that of the rat and guineapig respectively. Osmolality of pika urine was slightly higher than that of the rat, and was 3.8 fold that of the guineapig.