Milk fever is a common condition that causes cattle to go down and be unable to rise. You have probably heard the term milk fever, but this condition is misnamed because most affected cattle do not have a fever. The disease is also called parturient paresis. It is very common in dairy cattle but does occur in beef cattle as well. The syndrome, caused by low blood calcium (hypocalcemia), usually occurs just after calving. Decreased calcium in the diet and the inability of the cow to mobilize enough calcium from the bones to meet the demands of high milk production cause the syndrome. Most of the signs occur within 72 hours of calving. Cows with milk fever have decreased gut sounds, decreased appetite, and are usually found down on the ground. The symptoms of this condition differ from grass tetany, which causes hyperexcitability and muscle twitching, while cows with milk fever are very calm and sedate. These cows usually have enough calcium in their bodies, but their bodies cannot absorb and mobilize all the available calcium.
Diets high in calcium actually increase the chance of milk fever and although it seems counterintuitive, giving calcium before calving decreases the ability of the cow’s body to absorb calcium and mobilize stored calcium. On the other hand, if the amount of calcium fed prior to calving is low, the cow’s body is geared up to increase blood calcium and keep the level in the normal range when the calf is born and milk production increases. Generally, milk fever responds well with an intravenous calcium injection allowing these cows to get back on their feet. Oral calcium can be used as further treatment.