title: Metabolizable energy, nitrogen balance, and ileal digestibility of amino acids in quality protein maize for pigs.
abstract: BACKGROUND
  To compare the nutritional value and digestibility of five quality protein maize (QPM) hybrids to that of white and yellow maize, two experiments were carried out in growing pigs. In experiment 1, the energy metabolizability and the nitrogen balance of growing pigs fed one of five QPM hybrid diets were compared against those of pigs fed white or yellow maize. In experiment 2, the apparent and standardized ileal digestibility (AID and SID, respectively) of proteins and amino acids from the five QPM hybrids were compared against those obtained from pigs fed white and yellow maize. In both experiments, the comparisons were conducted using contrasts.
  
  
  RESULTS
  The dry matter and nitrogen intakes were higher in the pigs fed the QPM hybrids (P < 0.05) than in the pigs fed white or yellow maize. Energy digestibility (P < 0.001) and metabolizability (P < 0.01) were higher in the pigs fed the white and yellow maize diets than in those fed the QPM diets. The AID of lysine was higher (P < 0.01) in the QPM diets than in the white and yellow maize. The AIDs of leucine, isoleucine, valine, phenylalanine, and methionine were lower in the QPM diets than those of maize (white and yellow) (all P < 0.05). Maize (white and yellow) had greater SIDs of leucine, isoleucine, valine, phenylalanine, glutamic acid, serine, alanine, tyrosine, and proline (P < 0.05).
  
  
  CONCLUSIONS
  Based on these results, it was concluded that QPM had a lower metabolizable energy content and a higher amount of digestible lysine than normal maize.
authors.affiliation: CENID Fisiología, Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, km 1 Carretera a Ajuchitlán, 76280 Querétaro, México.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Mariscal-Landín
authors.affiliation: Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, México, Av. de las Ciencias s/n, 76230 Querétaro, México.
authors.forename: Tércia Cesária
authors.initials: TC
authors.lastname: Reis de Souza
authors.affiliation: CENID Fisiología, Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, km 1 Carretera a Ajuchitlán, 76280 Querétaro, México.
authors.forename: Ericka
authors.initials: E
authors.lastname: Ramírez Rodríguez
keywords: Amino acids; Energy balance; Maize; Nitrogen balance; Pigs