Differences in seasonal changes of fecal androgen levels between stabled and free-ranging Polish Konik stallions.

Abstract

Blood and feces samples were collected from Polish Konik stallions kept under conventional stable conditions and in the forest reserve during a 1-year study period. Levels of testosterone (T) and androstenedione (A(4)) were measured using radioimmunoassay. Positive correlation between fecal and plasma concentrations of androgens was observed. Fecal T concentrations increased in April and May reaching peak value mid-April in the stallions from the reserve group and 2 weeks later in the stallions from the stable group. Comparatively, concentrations of T were higher in the stable group. Levels of T decreased in July, increasing through August to September, and decreasing again in October. During this period of increase, concentrations of T were higher in the reserve group. A peak of fecal A(4) concentrations in the reserve group was noted mid-April, but high levels of this androgen appeared later and remained longer (also in May). When the breeding season finished, the concentration of A(4) decreased and remained low. During breeding season, concentrations of A(4) were higher in fecal samples taken from stable stallions than from those in the reserve group. During non-breeding seasons levels of this androgen in both groups were similar. The individual differences in the fecal androgen levels were dependent on the behavior of the stallions and were not related to their age. The seasonal changes of fecal T and A(4) levels differed between stabled and free-ranging Polish Konik stallions.