Possibility of early pregnancy detection in alpacas (Vicugna pacos) based on fecal steroid hormone concentrations

Early pregnancy detection in alpacas, whose breeding season is limited to the rainy season and has a long gestation period, is important for reproductive management. Conventional detection methods such as ultrasonography cannot be used to detect pregnancy before 30 days after mating. In this study, we examined the feasibility of using fecal steroid hormones as an early detection method in pregnant and non-pregnant alpacas. Fecal and blood samples were collected from pregnant and non-pregnant alpacas after mating. Progesterone (P4) and estradiol 17-β were extracted and quantified from blood and fecal samples. A positive correlation exists between the steroid hormones in serum and feces, indicating that serum steroid hormone concentrations can be estimated from fecal steroid hormones. Within 10 days after mating, both pregnant and non-pregnant alpacas had fecal P4 concentrations greater than 1.0 ng/mg dry matter (DM), but by 15 days after mating, fecal P4 concentrations decreased to the pre-mating concentration in non-pregnant alpacas. From 15 days after mating, non-pregnant alpacas had a low fecal P4 concentration (< 1 ng/mg DM), whereas a high fecal P4 concentration indicated the possibility of pregnancy, suggesting that this test is clinically beneficial as a supportive test for pregnancy detection.