An aetiological hypothesis for the nutrition-induced association between retained placenta and milk fever in the dairy cow.

In the dairy cow, a statistical association between milk fever (MF) and placental retention (PR) has been observed in epidemiological studies. In order to prevent both diseases, an understanding of their common aetiological mechanism is necessary. In this paper, a new causal hypothesis concerning the nutrition-induced association between PR and MF has been put forward. This hypothesis integrates the aetiological concepts arising from the studies carried out by the authors of this paper, and those reviewed from the literature. The aetiological pathway leading to associated MF and PR in the dairy cow appears to include 3 main interrelated mechanisms: 1), decreased synthesis of cyclooxygenase products (mainly PgF2 alpha) via precalving linolenic acid-rich diets; 2), lack of calcium availability at calving via calcium-rich diets before calving; 3), intensive lipomobilization around calving due to a lack of energy supply. The risk for both MF and PR appears to be maximum with old cows fed diets rich in green fodder (fresh or ensiled) and in calcium, and poor in cereals in the prepartum period.