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Objectives: Cows with subclinical hypocalcemia have no clinical signs of hypocalcemia but are more susceptible to other diseases. The objective of this study was to determine the prevalence of subclinical hypocalcemia in german dairy herds.
Materials and Methods: A multi-center study was performed involving 108 dairy herds and 26 different veterinary practitioners to determine the prevalence of subclinical hypocalcemia on German dairy farms. A sample size of about 1,300 animals with 12 animals per herd was required to estimate the true prevalence of subclinical hypocalcemia with 95 % confidence and 5 % precision. At least 12 serum blood samples were drawn on each farm from animals 0 to 48 hours after parturition. Calcium, magnesium and phosphorous was analyzed in a commercial laboratory. Subclinical hypocalcemia was defined as blood calcium below 2.0 mmol/l. Herds were classified into negative (0 to 2/ 12), borderline (3 to 5/ 12), and positive (≥ 6/ 12) according to the number of animals with subclinical hypocalcemia.
Results: So far, 348 samples from 29 herds have been analyzed. Overall, the prevalence of subclinical hypocalcemia in dairy cows was 36.8%. Prevalence increased with age and was present in 7.9%, 23.3%, 36.8%, and 55.1% of 1st 2nd, 3rd, and ≥4th lactation animals, respectively. There were 5, 15, and 9 herds classified into negative, borderline, and positive for subclinical hypocalcemia, respectively. The number of animals with subclinical hypocalcemia in a herd sample ranged from 1 to 9 out of 12 (8.3 to 75.0%).
Conclusions: Preliminary results indicate that the prevalence of subclinical hypocalcemia in German dairy herds is high. Subclinical hypocalcemia is considered a gateway disease in transition dairy cows leading to other clinical diseases such as metritis and displaced abomasum. Therefore further research is warranted to estimate the effect of subclinical hypocalcemia on health, milk production and reproductive performance on a cow and a herd level.