A basal mixture containing 35% soybean meal, 64.6% corn and 0.4 % methionine was used to formulate isocaloric and isoproteic diets for initiation, growth and finishing periods of development of native pigs, containing 16, 12 and 10% protein to be fed at8, 16 and 26 weeksof age, respectively. Lathyrus-used as the fiber source- was kept constant in the rations at levels of 16.4 and 32.8% for the three periods studied, reducing the content of the basal mixture in the diets on the basis of the protein contributed by the source of fiber added, and adding starch to maintain protein level constant. Information is presented on the digestibility of the nutrients of the diets for native pigs of 8 weeks of age on diets containing Ipomoea. Digestibility of cellular content decreased with fiber increment, although it improved at 26 weeks of age. Digestibility of acid detergent fiber, lignin and energy improved with age; nevertheless, they decreased between diets. Cellulose digestibility showed statistical differences among diets. Protein digestibility decreased with respect to fiber content, however, no significant differences were detected between age of animals and diets. Digestibility values between Lathyrus show significant differences in acid detergent fiber, lignin and cellulose in favor of Ipomoea.