Application of bovine rapid pregnancy test kit of the early pregnancy diagnosis in ewes in comparison with progesterone and pregnancy-specific protein B assays

The objective of the experiment was to identify the applicability of TARGET Bovine CL progesterone test kit (TARGET) for early pregnancy diagnosis in ewes. TARGET (BioMetallics, Inc.) is a commercial test kit to identify pregnancy in cows in the field. The test kit diagnostic result was assessed by standard color grade chart. When the blood or milk sample progesterone level is high, the test kit shows a white color and the cow is diagnosed as pregnant. The dark blue color indicates no-pregnancy, whereas the light blue and faint blue together indicate that there is no definite diagnosis, so a second test is required.In this experiment, 132 Merino ewes were divided into two groups. Eighty two ewes were assigned to a spring breeding flock at Rafter 7 Ranch (Yerington, NV), and the other 50 ewes were assigned to a fall breeding flock at Main Station Field Lab (MSFL, Reno, NV). In the Rafter 7 Ranch group, three diagnostic methods were applied to verify the reliability of the TARGET test kit: ELISA analysis of the blood progesterone level, ultrasound scanning for the pregnancy diagnosis, and the lambing records. An additional test called BioPRYN(Pregnancy Ruminant Yes/No) analysis, which tests PSPB(Pregnancy-Specific Protein B) level in the blood samples, was applied to the MSFL group.TARGET color grade readings, ELISA analysis, BioPRYN test results, ultrasound scanning results, and lambing records were analyzed by the FREQ procedure of the SAS (V 9.2) program to give the phi coefficients. For both groups, the cut-off value of ELISA progesterone assays to diagnose pregnancy in ewes was defined as >= 1 ng/ml. Six possible combinations within four color grades were evaluated separately. Sensitivity, specificity, and predictive values of TARGET kit color grade assignments for pregnancy diagnosis were calculated. For both groups, the color indicators of the TARGET test kit for early pregnancy diagnosis in ewes showed a significantly high phi coefficient (P<0.0001), a correlative association measured based on the lambing records. In conclusion, based on the results above, the bovine TARGET test kit is practically applicable to the early pregnancy diagnosis in the field for ewes with a high degree of accuracy.