Hypocalcemia at parturition as a risk factor for left displacement of the abomasum in dairy cows.

Total and ionized serum calcium concentrations were measured in 510 Holstein cows at the time of parturition. Cows that subsequently developed left displacement of the abomasum (LDA) were compared with those that did not. Cows that were hypocalcemic at parturition had a 4.8 times greater risk of developing LDA than did normocalcemic cows. Hypocalcemia was associated with the development of LDA whether ionized serum calcium concentration or total serum calcium concentration was used to determine whether cows were hypo- or normocalcemic. The proportion of cows developing LDA was not significantly different between cows that had clinical signs of hypocalcemia and were treated for parturient paresis and cows that were hypocalcemic, but did not have clinical signs and were not treated.