Steps to prevent milk fever in dairy cows.

Hypocalcaemia, or milk fever, is a common occurrence in dairy operations. While clinical hypocalcaemia is generally easy to spot and producers often have a treatment plan in place, sub-clinical cases are less easy to detect, especially if blood calcium levels are not routinely measured. The initiation of lactation requires a tremendous increase in the cow’s calcium requirement to meet demands for milk synthesis. About 20 to 30 grams of calcium per day are needed for milk production compared with 8 to 10 grams per day for fetal development just prior to calving. Thus, metabolic adaptations must take place to support the increased need for calcium. If they do not take place soon enough or are of insufficient magnitude, the concentration of calcium in the blood drops below a critical threshold and clinical and sub-clinical hypocalcaemia (milk fever) can result. Milk fever can have lasting effects in the cow’s production cycle, and every effort should be made to reduce its incidence. This article explores management practices, feeding best practices and on-farm tools that can be used to help minimize clinical cases and/or catch sub-clinical cases. Calcium is the most abundant mineral in the body with the vast majority being found in bone. The remainder (only ~1 percent) is vital for nerve function, muscle contraction and cell signalling. There is internal regulation of blood calcium levels involving parathyroid hormone (PTH), calcitonin and Vitamin D3 (1, 25-dihydroxycholecalciferol), known as calcitriol. Regulation involves calcium moving into or out of the skeleton, as well as dietary uptake of calcium from the small intestine. In situations of low blood calcium, PTH is secreted resulting in a greater amount of skeletal calcium that is resorbed and released into the blood. Parathyroid hormone release stimulates renal production of calcitriol, which then increases the absorption of calcium from the small intestine. Read