MANGANESE IN RUMINANT NUTRITION

Abstract

Manganese (Mn) is an essential dietary element for ruminants. All ruminant tissues contain Mn in low concentrations and the variability of concentration within tissues is small. The highest concentration occurs in the glandular organs, particularly the liver, pancreas and kidney. Ruminants have an effective homeostatic control for Mn levels in blood and tissues and Mn retention by the animal depends on the amount excreted from the bile into the intestine. Dietary Mn is mostly excreted in the feces. A level of 40 ppm Mn appears to be sufficient in practical diets for optimum performance. Blood Mn levels may decline slowly following a very low Mn intake. The liver contains the most important mobilizable Mn stores but the hepatic capacity to store Mn for lengthy periods is limited. Manganese is widely distributed in roughages but in some cereals such as corn, low amounts of Mn have been found. High dietary Ca levels reduce the availability of Mn in cattle. It has been shown that a deficiency of Mn results in more services per conception and in irregular or absence of estrus in females. In males, Mn deficiency is associated with seminal tubular degeneration. The offspring of dams subjected to Mn deficiency often have malformed bone structure characterized in calves by enlarged joints, twisted legs, and in kids with bowing or shortening of the forelegs and sometimes paralysis of the extremities. Calves from cows on a Mn-deficient diet have shown tremor of the tongue shortly after birth and incoordination.