Fecal Progestagen Concentration as an Indicator of the Estrous Cycle and Pregnancy in Moose

We established a noninvasive technique for monitoring the estrous cycle and pregnancy in moose (Alces alces). We collected fecal samples daily from nonpregnant yearling females (n = 3) for the duration of 3-4 estrous cycles, and weekly throughout gestation from 3 pregnant adult cows. We analyzed samples by radioimmunoassay (RIA) to quantify the concentration of progestagen metabolites. Peak luteal phase concentrations of progestagens were 4.5 ± 0.9 (SD) μg/g compared with 0.5 ± 0.1 μg/g during the follicular phase. Observed (n = 7) and suspected (n = 2) matings all occurred within ±2 days of the nadir in progestagen excretion. Fecal progestagens were above peak luteal phase concentrations by the eighth week of gestation (>7 μg/g of feces, P < 0.001), permitting accurate pregnancy detection by this time. Relative concentrations of fecal progestagens during the follicular phase, luteal phase, and pregnancy were 1:10:35, respectively. Monitoring fecal progestagen is a useful noninvasive technique for tracking ovarian activity and pregnancy in moose.