Magnesium Requirement of the Laying Hen for Reproduction

Abstract

Three experiments were conducted to determine the magnesium (Mg) requirement of the laying hen. Hens fed a semipurified basal ration containing 55 ppm Mg developed anorexia, hypomagnesemia, nervous tremors and seizures within 2 weeks. A severe decrease in egg production, egg weight and hatchability of eggs was also observed. Feeding a ration containing 155 ppm Mg improved egg production, but not egg weight or hatchability. The reduction in hatchability preceded decreases in appetite and egg production, and was closely associated with hypomagnesemia in the hen and lower concentration of magnesium in the egg. Magnesium concentration in the dry matter of livers from hens fed the basal ration was markedly decreased whereas calcium concentration was increased. When expressed on a fat-free basis, however, the magnesium concentration in the livers was not significantly affected by ration treatment. Histological studies of the liver from hens fed the basal ration showed a considerable accumulation of fat globules in the cells. Oxidative phosphorylation, measured as P/O ratio of liver homogenates, from hens fed a magnesium-deficient ration was approximately half that of liver from control hens. The results show that the hen (1.8 to 2.0 kg body weight) requires a minimum of 355 ppm Mg in the diet or an intake of at least 36 mg Mg/day to maintain a high rate of egg production, desirable egg production, desirable egg weight and high rate of hatchability of fertile eggs.