Feeding High Levels of Litter in Late Gestation May Cause Milk Fever
Livestock Update, September 1999
John B. Hall, Extension Animal Scientist, Beef, Virginia Tech
In a recent livestock update, rations for cows using poultry litter were listed. However, one caution about using litter in cows in late gestation. Poultry litter contains high levels of calcium. When cows are fed high levels of calcium in late gestation, it interferes with the normal mobilization of calcium from bone stores. As a result when cows calve, they cannot mobilize calcium from the bone rapidly enough to meet demand for calcium in the milk. Calcium is then drawn out of another body store -- the muscle. Calcium is needed in muscle to cause muscle contraction. When muscle stores are depleted, cow becomes essentially paralyzed and the symptoms of Milk Fever (parturient paresis) show up. The risk of milk fever in beef cows, though small, is highest in high milking breeds like Angus, Gelbvieh, Shorthorn, and others.
There have been several reports of milk fever in cows fed high litter rations in late gestation. In beef cows immediately after calving, research at Virginia Tech has demonstrated blood calcium levels were low and consistent with calcium levels seen in cows with milk fever if the cows were on high litter diets late in gestation. The non-litter fed cows had normal blood calcium levels. However, none of the litter fed cows exhibited symptoms of milk fever.
To prevent the possibility of milk fever, litter should not make up more than 50% of the diet in cows during the last 2 months of pregnancy.