24 Investigating pregnancy diagnosis methods in scimitar-horned oryx (Oryx dammah)

Accurate pregnancy diagnosis methods are essential to ex situ population management of endangered species. To augment population management of the endangered scimitar-horned oryx (Oryx dammah), the objective of this study was to investigate fecal and serum progesterone enzyme-linked immunoassays (EIA) and two commercially available pregnancy associated glycoproteins (PAG) assays (Rapid Visual Pregnancy Test, IDEXX; BioPRYN®, Herd Health Diagnostics) as methods to diagnose pregnancy. Sixteen females of an unknown pregnancy status and age were anesthetized and reversed using the BAM^TM Kit (Wedgewood), and pregnancy was diagnosed using transrectal/abdominal ultrasonography (US; Vetus EQ, Mindray; 6LE5Vs). At the time of the examination, paired serum and feces were collected and stored at −20°C until analysis. Subsequent parturition dates were used to calculate the gestation day when the females were examined. Feces were extracted using 90% ethanol:water. Both serum and feces were analyzed using a double antibody progesterone EIA using a monoclonal antibody (CL425, Quidel Co.) and 96-well microtiter plates precoated with goat anti-mouse IgG (Arbor Assays). Serially diluted pools of serum and fecal extracts both yielded displacement curves parallel to serially diluted progesterone standard, and recovery of known concentrations of progesterone added to pools of serum and fecal extracts were 100.3% and 106.0%, respectively. For the Rapid Visual Pregnancy Test serum samples were analyzed according to manufacturer instructions. For BioPryn analysis, serum samples were shipped frozen to Herd Health Diagnostics. Statistical analyses were performed using SigmaPlot V15.0. Data are reported as mean ± SEM. Differences in serum and fecal progesterone concentrations were evaluated using Mann-Whitney rank sum test. At the time of sampling, pregnant females ranged between ~108 and 251 days of gestation. Serum and fecal progesterone concentrations were significantly (P < 0.05) higher in pregnant females (n = 8; serum 142.1 ± 31.4 ng mL⁻¹, range 40.2–278.6 ng mL⁻¹; fecal 26.9 ± 5.6 ng mL⁻¹, range 12.1–35.8 ng mL⁻¹) than nonpregnant females (n = 8; serum 0.9 ± 0.2 ng mL⁻¹, range 0.3–1.8 ng mL⁻¹; fecal 1.8 ± 0.1 ng mL⁻¹, range 1.3–2.3 ng mL⁻¹). The Rapid Visual Pregnancy Test resulted in eight true-positives, three false-positives, and five true-negatives. The BioPRYN assay resulted in 100% accuracy with eight true-positives and eight true-negatives. Owing to unknown age, it was not possible to determination whether nonpregnant individuals were sexually mature or immature. Reliable pregnancy diagnoses were obtained with serum and fecal progestin concentrations and with the BioPRYN PAG assay. As the earliest PAG detection in cattle is 40 days, future studies will investigate the earliest pregnancy detection of PAG in scimitar-horned oryx using the BioPRYN assay. Together, the serum and fecal progesterone analysis and the BioPRYN PAG assay provide animal health professionals with additional methods other than US to aid in pregnancy diagnosis, augmenting the population management of this species.