The Utilization of a Pregnancy-Associated Glycoprotein Profile and PAG/P4 Ratio Biomarker for the Diagnosis of Pseudopregnancy in Dairy Goats

Abstract

Pseudopregnancy (PPG) is a common reproductive disorder in dairy goats, characterized by the accumulation of sterile fluid in the uterus and persistence of a corpus luteum, leading to temporary infertility and reduced farm efficiency. This study aimed to determine the pregnancy-associated glycoprotein (PAG) profile in dairy goats and to evaluate the PAG/P4 ratio as a potential novel biomarker for PPG diagnosis. A total of 605 Saanen and crossbreed mated goats were evaluated via transabdominal ultrasonography between 31 and 52 days after the removal of bucks in four intensive dairy farms, presenting an overall PPG incidence of 7.8%. Blood samples from PPG (n = 47), nonpregnant (NPG; negative control; n = 11), and pregnant (PG; positive control; n = 10) does were collected for PAG and P4 analysis. The PAG plasma levels were 0.08 ± 0.02, 0.13 ± 0.04, and 1.45 ± 0.04 OD (optical density) in the PPG, NPG, and PG groups, respectively (p < 0.001). The PAG/P4 ratio was lower in the PPG group (0.01 ± 0.11; p < 0.001) than in the NPG (0.24 ± 0.23) and PG (0.18 ± 0.23) groups. This difference allows for the establishment of a new methodological diagnostic approach to PPG. The area under the curve (AUC) was 0.996 for a cut-off of 0.04 and 97.9% and 100% sensitivity and specificity, respectively. This study suggests that the PAG/P4 ratio can serve as a reliable biomarker for PPG diagnosis, helping to distinguish it from pregnancy and nonpregnancy and improving reproductive management in dairy goats.