Establishment of a standard operating procedure for predicting the time of calving in cattle

Precise calving monitoring is essential for decreasing the
consequences of dystocia in cows and calves. The progress of seven
clinical signs (broad pelvic ligaments relaxation, vaginal
secretion, udder hyperplasia, udder oedema, teat filling, tail
relaxation, and vulva oedema) in the preparatory stage were
evaluated in two studies on healthy cows (n = 104) and heifers (n =
41) for the investigation of their suitability alone and in
combination to predict the time of parturition. The animals were
examined during (at least) the last three days before calving on a
daily basis at 8:00 a.m. A commercial progesterone rapid blood test
(PRBT) was used as an additional tool for calving prediction, which
was compared to a validated enzyme immune assay. The parturition
score (PS) combines the sum of the PS-points of the relaxation of
the broad pelvic ligaments (PS-points: 0; 2; 4; 6) and filling of
the teats (PS-points: 0; 1; 2; 3) because these signs reported the
best predictive value of all examined signs and the highest inter-
and intra-observer reliability. In the PS, two thresholds of
PS–points were defined (PS ≥ 4 and PS ≥ 5). Below PS 4 calving
within 12 h could be ruled out with a probability of 99.3% in cows
(95.5% in heifers). If a PS ≥ 5 is used calving within 12 h can be
ruled out with a probability of 98.0% in cows (94.9% in heifers).
Above this threshold, application of the PRBT (sensitivity: 90.2%;
specificity: 74.9%) was recommended. If the PRBT indicates an
inactive corpus luteum, intermitted calving monitoring every three
hours is recommended. By combining the PS and PRBT (if PS ≥ 4), the
prediction of calving within the next 12 h improved from 14.9% (PS
alone) to 53.1% and the probability of ruling out calving was
96.8%. If a PS ≥ 5 is used the probability to predict calving
within the next 12 h is 65.8% and the probability of ruling out
calving 93.3%. The developed standard operating procedure that
combines PS and PRBT will enable veterinarians the ability to rule
out or predict calving within the next 12 h in peripartal animals
with a relatively high accuracy under field conditions with only
one single examination.