Clinical signs, progesterone test predicts calving time in cattle
MedWire News: Predicting calving time within a 12-hour timeframe in cattle is possible using a combination of four clinical signs and a progesterone rapid blood test (PRBT) during monitoring, suggest study findings.
"The standard operating procedure established in our study provides a validated method for determining whether calving within a 12-hour time period is possible," say Dominik Streyl (Ludwig-Maximilian University of Munich, Germany) and co-authors.
They add: "This will help to improve calving monitoring and the management of individual cows with health problems or a history of difficult births, and animals that have special genetic value."
The researchers performed two studies among 145 healthy cows (of which 124 were from a large dairy farm) that compared seven clinical signs alone and in combination to predict time of parturition. These included broad pelvic ligament relaxation, vaginal secretion, udder hyperplasia, udder edema, teat filling, tail relaxation, and vulva edema.
The alteration of each clinical sign during the preparatory stage to its maximum was divided in four steps, which were allocated parturition score (PS) points from 0 to 3 according to severity. These could be double or triple weighted to provide a maximum score of 9.
Analysis revealed that the best clinical indicator for calving within 12 hours was relaxation of the pelvic ligaments followed by filling of the teats. When tail relaxation and vulva edema were included in the model, the team found that this combination of four parameters provided the best accuracy for ruling out calving within 12 hours.
Indeed, the team found that a cutoff value of 4 PS points accurately predicted "no calving within 12 hours" in cows in 99.3% of cases, with a corresponding sensitivity of 94.7% and specificity of 57.8%.
In heifers, the predictive value of the PS was slightly different, at 95.5% accuracy for predicting "no calving" (sensitivity 55.6% and specificity 74.3%).
Above a threshold of 4 PS points, intermittent calving monitoring every 3 hours and PRBT would be recommended, say the authors. Compared with the standard quantitative progesterone EIA analysis, PRBT had a sensitivity of 90.2% and specificity of 74.9% for detecting progesterone levels above or below 1.2 ng/ml.
Combining the PS and PRBT (if PS≥4) significantly improved the prediction of calving within the next 12 hours from 14.9% to 53.1%, while the probability of ruling out calving remained high, at 96.8%.
Writing in the Journal of Veterinary Science, Streyl and team conclude: "The SOP established in our study has to be further validated by a prospective study with healthy cows as well as cows suffering from health problems such as prepartum hypocalcaemia or ketosis."
By Ingrid Grasmo