Validation of a Pregnancy‐Associated Glycoprotein–Based Lateral Flow Assay for Early Pregnancy Detection in Goats

BACKGROUND: The significant cross-reactivity between bovine, ovine, and caprine pregnancy-associated glycoproteins (PAGs) enables the adaptation of bovine-specific diagnostics for use in other ruminants; consequently, the Alertys OnFarm Pregnancy Test (AOFPT)-a blood-based lateral flow assay-provides a rapid and practical solution for pregnancy detection directly at the animal's head under field conditions. OBJECTIVES: This study evaluated to assess and validate the performance of AOFPT in goats at days 21 and 28 post-mating, by comparing the results with serum progesterone (P4) analysis and using transabdominal ultrasonography (TAUS) as the gold standard. METHODS: The study involved 85 Kilis goats, five months post-partum. Estrus was synchronized using an 11-day progestagen device, d-cloprostenol, and PMSG. Whole blood and serum samples were collected on Days 21 and 28 post-mating. AOFPT was performed on-farm immediately after collection. For validation, serum progesterone concentrations were measured via electrochemiluminescence immunoassay, and TAUS was performed on Days 35 and 42, with Day 42 findings serving as the gold standard. RESULTS: Results indicated that on Day 21, AOFPT sensitivity, specificity, positive predictive value, and negative predictive value were 79.4%, 93.8%, 98.2%, and 51.7%, respectively. By Day 28, these metrics reached 100%, 81.3%, 95.8%, and 100%. Statistical agreement between AOFPT and the reference method was K = 0.55 (82.14%) on Day 21 and K = 0.87 (96.43%) on Day 28 (p <0.001). Median ± interquartile range (IQR) of P4 concentrations were 5.95±2.60 ng/mL on day 21 and 6.92 ± 2.93 ng/mL on Day 28. AOFPT-identified pregnant goats exhibited significantly higher P4 levels (p < 0.001) than non-pregnant goats on Day 21 (5.98 ± 3.21 vs. 4.05 ± 5.46) and Day 28 (6.84 ± 3.06 vs. 0.75 ± 5.96). CONCLUSIONS: AOFPT demonstrated accuracy and reliability closely matching P4 measurements and the reference method. This test provides a practical tool for early on-farm pregnancy diagnosis in goats, potentially enhancing reproductive management and productivity in dairy goat farms and large herds.