Abstract
We have previously demonstrated that the gonadal function of sika deer (Cervus nippon) can be successfully monitored by using fecal steroid analysis. In this study we examined some technical aspects of applying this method to the estimation of the reproductive status of wild sika deer. Enzymeimmunoassays (EIA) for fecal progesterone and testosterone were established, and the fecal concentrations of these steroids obtained were compared with those measured by conventional radioimmunoassays (RIA). The patterns of fecal progesterone during the estrous cycle and the annual fecal testosterone profile in a male deer measured by EIA were virtually identical with those measured by RIA. Then the effect of environmental temperature on the fecal progesterone concentration was examined by monitoring the change in fecal progesterone at 4 C and 20 C up to 144 h after defecation. Fecal progesterone levels increased markedly at 20 C (but not at 4 C) with the degree of increase being variable in each sample. This increase was inhibited by adding ethanol, antibiotics or silica gel. It therefore appears that the increase was caused by the action of intestinal microorganisms, which converted conjugated steroids to unconjugated forms. These results suggest that wild sika deer fecal samples should be collected in winter time when the environmental temperature is low for steroid analysis in field conditions. The EIAs appeared more feasible means for field-endocrinological studies than RIA considering their simpler and less time-consuming procedures.
