Abstract :
[en] In the present study we report the use of a new PAG-ELISA for routine pregnancy diagnosis in cattle.
A total of 2777 samples were collected from pregnant or non-pregnant cows and assayed by both classical PAG RIA-497 method and newly developed PAG-ELISA (Ref. code E.G.7, CER, Maloie). Pregnancy status was determined on the basis of RIA results. Samples were assumed to be issued from pregnant cows when PAG concentrations were higher than 0.8 ng/mL. PAG concentrations <0.8 ng/mL were considered negative (non-pregnant). PAG concentrations between 0.8 and 1.0 ng/mL were considered doubtful. With regard to ELISA, concentrations below 0.6 were considered negative. Concentrations between 0.6 and 0.8 ng/mL were considered doubtful and finally concentrations under 0.8 ng/mL were assumed as positive.
Sensitivity(Se), specificity(Sp) and predictive values (PV) of pregnancy diagnosis were determined. A total of 143(5.2%), 137(4.9%) and 38(1.4%) samples gave doubtful results by RIA, ELISA or both systems, respectively. These samples (318/2777=11.5%) were not used for estimation of Se, Sp, PPV and NPV because clinical confirmation of pregnancy diagnosis could not be established by an additional method (rectal palpation, ultrasound or calving). Taking into account the remaining samples (2459), Se, Sp, PPV and NPV obtained by ELISA were respectively 98.9%, 89.9%, 98.7% and 96.4%.
In conclusion, PAG-ELISA can be successfully used for pregnancy diagnosis in cattle. In the near future, further investigations are to be conducted in order to compare results obtained by ELISA test with those obtained by rectal palpation and ultrasound in field conditions.
