[Nutritive value of raw and processed cowpeas]. / Valor nutritivo del frijol caupí crudo y procesado.

Three experiments were carried out to determine the effects of autoclave cooking, extrusion and DL-methionine supplementation on the protein and energy value of cowpea. The two processes decreased the available lysine of cowpea from 6.3 to 5.7%. The starch content decreased from 50.7% in raw cowpea to 44.9% and 42.1% in cooked extruded cowpea, respectively. Cooking eliminated the trypsin inhibitor content of cowpea. Damaged starch increased from 0.3% in the raw cowpea, to 22.5% in cooked cowpea and to 30.5% in extruded cowpea. In the first experiment it was determined that the protein efficiency ratio (PER) in rats was not affected by cowpea processing (means = 1.17) and that DL-methionine supplementation increased (P less than 0.01) PER to 2.08. In the second experiment, it was established that energy digestibility of the diets used in the first experiment averaged 88.0% with no differences due to processing or supplementation. Digestible energy content (DE) was lower (P less than 0.01) in diets supplemented with DL-methionine (3.58, 3.56, 3.93) than in those without supplement (3.67, 3.93, 3.75). On the other hand, diets with extruded cowpea produced higher (P less than 0.01) DE (3.84 kcal/g) than diets with cooked cowpea (3.75 kcal/g). Classical (EM) and nitrogen corrected (EMn) metabolizable energy determined in chicks showed that both were higher (P less than 0.01) in cooked (3.01; 2.56 kcal/g) and extruded (3.16; 2.76 kcal/g) than in raw cowpeas (1.86; 1.81 kcal/g).