Abstract
Although sika deer is valuable for deer farming in Japan, little is understood about the reproductive endocrinology of the male. Especially, there is no information on the blood LH concentration in male sika deer. The present study aimed to determine the annual changes of serum LH and testosterone (T) secretion in male sika deer. Blood samples were collected monthly from three stags for 3 years (1998-2000). Serum LH and T concentrations were determined using a second-antibody enzyme immunoassay and a time-resolved fluorescent immunoassay, respectively. The serum LH and T concentrations fluctuated obviously in an annual fashion. The LH concentrations peaked in May, June and July, while the T concentrations peaked in September and October. These results suggest that LH and T secretion in adult male sika deer are mainly controlled by annual rhythm in the same manner as in other temperate cervids.
