ORGANIC MAIZE: CHANGES IN AMINO ACID COMPOSITION

Abstract

The aim of this study was to assess the bromatological quality and the content of essential amino acids in maize grains produced using two different cropping systems: organic and conventional. The experimental area was 4 hectares, divided into 2 hectares per system. In the conventional management, agrochemicals from conventional maize production were used. In the organic management, inputs permitted by the current Brazilian legislation on organic production were used. For each system, 10 plots of 9 m² each were established, from which experimental samples were harvested. The method described by Silva & Queiroz (2002) was used to determine bromatological quality. Near-infrared reflectance spectroscopy (NIRS) was used to quantify essential amino acids. A significant difference was found in the bromatological quality of maize grains. The conventional management provided greater crude protein content. Significant changes were also found in the following amino acids: methionine, threonine, arginine, isoleucine, leucine, valine, histidine, and phenylalanine, which showed lower levels in the organic management. The results confirm the need to determine food composition before diet formulation, since using preestablished food compositions probably leads to differences between what was formulated and what was actually given to poultry. The type of management influenced the quality of maize grains. The management of plant nutrition in the organic system should be refined to adequately supply nitrogen, thus improving bromatological and amino acid quality of the grains.