Nutritive Value and Digestibility of Opaque-2 and Normal Corn for Growing Pigs

The opaque-2 mutant gene causes an alternation in the amino acid pattern of corn endosperm protein resulting in higher lysine and tryptophan levels than those normally found in hybrid corn (Mertz, Bates and Nelson, 1964; Nelson, Mertz and Bates, 1965; Nelson, 1966). Studies with rats, pigs, chicks and quail have shown that the nutritional value of opaque-2 corn is superior to that of normal corn (Mertz et al., 1965; Cromwell, Pickett and Beeson, 1967a; Cromwell et al., 1967b, 1968; Zucker, Erbersdobler and Gropp, 1968). Some data suggest that pigs require less supplemental protein when fed opaque-2 corn as compared with those fed normal corn (Beeson et al., 1966; Jensen, Becker and Harmon, 1967; Cromwell et al., 1969). Drews et al. (1969) estimated that 5% less soybean meal was required in diets containing opaque-2 corn than in those with normal corn to support maximum performance of pigs and chicks. Nitrogen balance studies with pigs suggest that the protein of opaque-2 corn not only has a higher biological value than that of normal corn, but it is also more digestible (Cromwell et al., 1969).