Hypocalcaemia and DCAD for the pasture-based transition cow--a review.

Hypocalcaemia or milk fever is a condition resulting from an insufficiency of plasma calcium to maintain proper body function and is probably the most prevalent mineral-related disorder faced by the transition cow. It is also referred to as parturient paresis or parturient paralysis due to the recumbency that accompanies the most common hypocalcaemia, that is hypocalcaemia that occurs at or around calving. Milk fever was first reported in Germany in 1793 and since then has been the study of many researchers because of its economic importance, reducing milk production by 7 to 14%, depending on the degree of severity. Its prevention has been addressed by different methods including deliberately changing the blood acid-base balance through supplementation of metabolically strong anions (chlorine and sulphur) in an attempt to improve calcium homeostasis in the periparturient cow. This adjustment to the systemic acid-base balance of the cow is difficult to achieve practically and consistently in pasture-based systems and recent research has questioned its efficacy in maintaining a periparturient eucalcaemia.