Effect of Fermented Soybean, "Natto" on the Production and Qualities of Chicken Meat

Natto is a Japanese traditional soybean product fermented by Bacillus natto. The effect of natto supplement on the production and qualities of chicken meat was studied since the effective use of various waste foods is required in Japan. Dried natto prepared by heating at $60^{\circ}C$ was added to a basic diet at an amount of below 2%. The supplementation of dried natto did not influence the weights of the carcass, breast and thigh meat, fillet or abdominal fat. Growth of the thighbone such as the length, thickness of cortex bone, and Ca/P ratio in bone ash were not altered by the addition of natto. However, the pH of male meat decreased following the supplementation of dried natto from days 28 to 80. The water-soluble protein content in male thigh meat increased in the group fed 2% natto from days 28 to 80. Free peptides increased in male thigh meat by feeding 2% natto from days 0 to 80. The supplementation of natto increased free glutamic acid in thigh meat regardless of sex. Moreover, the supplementation of natto specifically decreased meat cholesterol in female chickens though the effect was not shown in male chickens.