The Influence of Tryptophan, Methionine and Lysine Supplementation of a Corn-Soybean Oil Meal Diet on Nitrogen Balance of Growing Swine

MANY investigations have been conducted to determine the amino acid content of a wide variety of feedstuffs, many of which are commonly used in typical swine diets (Block and Mitchell, 1946; Baumgarten et al., 1946; Williams et al., 1955). The lysine requirement for growing pigs has been reported by Mertz et al. (1949), Brinegar et al. (1950) and Shelton et al. (1951a). A strict tryptophan deficiency was first produced in growing pigs by Beeson et al. (1949), and the requirement set forth by the National Research Council (1953) is based on the work of Shelton et al. (1951b, 1951c). Bell et al. (1950) and Curtin et al. (1952) have reported the methionine requirement for growing swine. A comparison of these reported essential amino acid requirements of growing pigs with calculated amino acid content of many practical diets, particularly those containing lower levels of protein, reveals that many such diets may be inadequate in these essential amino acids. Several workers (Bloss et al., 1953; Terrill et al., 1954; Henson et al., 1955) have recently demonstrated that the addition of small amounts of dl-tryptophan to corn-meat by-product type of diets improved them for growing-fattening pigs.