Relative bioavailability of manganese in a manganese-methionine complex for broiler chicks

The relative bioavailability of Mn from reagent grade Mn monoxide and feed grade Mn-methionine was compared with that from reagent grade Mn sulfate using 288 one-day-old male Cobb chicks. The basal corn-soybean meal diet (93 ppm Mn dry matter basis) was supplemented with 0, 700, 1,400, and 2,100 ppm Mn as Mn sulfate monohydrate, Mn oxide, or Mn-methionine. Additional diets contained 700, 1,400, and 2,100 ppm Mn as sulfate or oxide in combination with .16, .32, or .48% added DL-methionine, respectively, to equalize methionine concentrations in Mn-methionine-containing diets. Diets were fed ad libitum for 3 wk. Tibia and kidney Mn concentrations increased linearly (P less than .001) as dietary Mn increased. Addition of methionine to diets containing sulfate and oxide did not influence (P greater than .10) tissue Mn concentrations. Based on slope ratios from multiple linear regression of bone and kidney Mn concentrations on added dietary Mn from various sources, the respective relative bioavailability values were 96 and 86% from Mn oxide and 108 and 132% from Mn-methionine compared with 100% from Mn sulfate. Except for the first, all values were significantly different from 100%. Thus, Mn from Mn oxide is significantly less available and Mn from Mn-methionine is significantly more available than that from Mn sulfate monohydrate.