Comparative diagnosis of pregnancy wastage in cows at slaughter using pregnancy specific protein-B and post slaughter inspection diagnostic procedures

Abstract

Slaughter of pregnant animals is a common abattoir practice. This study was designed to compare the diagnostic capacity of pregnancy specific protein-B (PSPB) with post slaughter inspection (PSI) procedures in detecting cows pregnant at slaughter. Blood was collected from cows presenteded for slaughter at an abattoir. The uteri were examined post slaughter for the presence or absence of a foetus. Recovered foetuses were aged using crown-rump length to estimate the stage of pregnancy. Of the 361 cows examined, 72 (19.9 %) were diagnosed pregnant using the PSPB procedure, while 32 (8.9 %) were diagnosed pregnant using PSI diagnosis. Furthermore, with PSI there was a lack of pregnancy diagnosis in 42 (11.6 %) cows detected pregnant using PSPB procedure, and two (0.6 %) cows detected pregnant using PSI were not detected to be pregnant using PSPB diagnosis. Validity of the diagnostic procedures indicated that sensitivity and specificity of the PSPB was 93.8 % and 87.2 %, respectively, while with the PSI diagnosis there was a sensitivity and specificity of 41.7 % and 99.3 %, respectively. The PSPB diagnosis, had an excellent predictive value (AUC – 0.92; p < 0.001; 95 % CI – 0.856 to 0.981). Most of the pregnancy wastage (n = 22; 68.8 %) diagnosed using the PSI method were in the second trimester. The results of this study indicate that PSPB is reliable and a more sensitive diagnostic method than PSI . It is therefore recommended that the PSPB test be incorporated in routine screening for pregnancy status of cows before slaughter.