2.4. Field experiment
This study was approved by the German legislation on
animal welfare (Lower Saxony Federal State Office for
Consumer Protection 279 and Food Safety, AZ 33.14–
42502-04-13A/368). In total, 297 heifers and pluriparous
Holstein-Friesian cows (parity of 2.471.8) from 12 different
dairy farms were included in the study. TRU was carried
out during routine pregnancy examinations (at 28–60
days p.i.) performed by the ambulatory service of the
Clinic for Cattle. Simultaneously, a blood sample was
drawn from the coccygeal vessels at the respective day
(28–60. p.i.) for later PAG analysis. In cows with differing
(TRU≠PAG) or questionable results, the pregnancy status
was re-checked by TRU and PAG analysis within 7–30 days.
For all other cows, calving was assessed to confirm the
physiological pregnancy outcome.
Data evaluation included the calculation of the following
test characteristics: the SEN, SPE, positive and negative predictive
values (PPV and NPV), accuracy, positive and negative
likelihood ratios (LRþ and LR), and diagnostic odds ratio
(DOR). For the prediction/diagnosis of EM/FM, all first examinations
were included in the evaluation of the test characteristics.
The re-check results were used as the gold standard
to confirm or deny the test results. Evaluations for the
test characteristics were performed for the prediction/diagnosis
of EM/FM by both PAG-ELISA exclusively (non-pregnant
cows excluded) and by the combined evaluation of the TRU
and PAG-ELISA results. Calculations were performed separately
for the three aforementioned cut-off values (a PAG-OD
of 1.5 as previously defined by measuring PAG after induction
of fetal mortality due to PGF2α injection on day 33 of pregnancy
(unpublished data) and the two cut-off values obtained
2.4. Field experimentThis study was approved by the German legislation onanimal welfare (Lower Saxony Federal State Office forConsumer Protection 279 and Food Safety, AZ 33.14–42502-04-13A/368). In total, 297 heifers and pluriparousHolstein-Friesian cows (parity of 2.471.8) from 12 differentdairy farms were included in the study. TRU was carriedout during routine pregnancy examinations (at 28–60days p.i.) performed by the ambulatory service of theClinic for Cattle. Simultaneously, a blood sample wasdrawn from the coccygeal vessels at the respective day(28–60. p.i.) for later PAG analysis. In cows with differing(TRU≠PAG) or questionable results, the pregnancy statuswas re-checked by TRU and PAG analysis within 7–30 days.For all other cows, calving was assessed to confirm thephysiological pregnancy outcome.Data evaluation included the calculation of the followingtest characteristics: the SEN, SPE, positive and negative predictivevalues (PPV and NPV), accuracy, positive and negativelikelihood ratios (LRþ and LR), and diagnostic odds ratio(DOR). For the prediction/diagnosis of EM/FM, all first examinationswere included in the evaluation of the test characteristics.The re-check results were used as the gold standardto confirm or deny the test results. Evaluations for thetest characteristics were performed for the prediction/diagnosisof EM/FM by both PAG-ELISA exclusively (non-pregnantcows excluded) and by the combined evaluation of the TRUand PAG-ELISA results. Calculations were performed separatelyfor the three aforementioned cut-off values (a PAG-ODof 1.5 as previously defined by measuring PAG after inductionof fetal mortality due to PGF2α injection on day 33 of pregnancy(unpublished data) and the two cut-off values obtained
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