Chemical characterization and quantification of phenolic compounds in forage grasses / CaracterizaÃÃo quÃmica e quantificaÃÃo de compostos fenÃlicos em forrageiras

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The chemical characterization and determination of the phenolic compounds present in forage is of great importance as it allows for a better use of these plants in animal nutrition. This study characterized the chemical and bromatological composition of the forages Stylosanthes guianensi; MineirÃo and Campo Grande cultivars, and Arachis pintoi; Amendoim Belmonte and Amendoim Amarillo cultivars, in association with âCoastcrossâ grass. The phenolic compounds present in these forage crops were identified and quantified using the high-performance liquid chromatography technique (HPLC) coupled to a diode array detector. The legumes cultivated in association obtained more appropriate levels, for animal nutrition, of dry matter (DM), acid detergent fiber (ADF), neutral detergent fiber (NDF) and lignin and higher phosphorous, calcium and raw protein (RP) levels than âCoastcrossâ grass. Only the phosphorous levels of fertilized âCoastcrossâ grass presented significant difference (P <0.05) from those in association. An increase was not observed in the level of RP in the associated grass due to the short duration period of this experiment. The legume, in association, which presented the best results for all of the appraised parameters was the Amendoim Amarillo. The association did not interfere in the level of polyphenols of the grasses, and in general, these levels were higher for the legumes. The phenolic acids (ferulic acid, p-coumaric, m-coumaric, o-coumaric acids), acids derived from the hydrolysis of hydrolysable tannins (gallic acid, ellagic acid and caffeic acid), condensed tannin monomers (catechin, epicatechin, epigallocatechin-gallate, gallocatechin), vanillin and quercetin were identified and quantified using the HPLC technique. The concentrations of acids derived from the hydrolysis of hydrolysable tannins found were from 0.19 to 113.98 Âg mg-1 MS. The concentrations of condensed tannin monomers were superior to those considered safe for ruminants (0.72 to 126.8 Âg mg-1 MS). A more in-depth study of these levels is necessary when the establishment of pastures associating âCoastcrossâ grass and the studied legumes becomes necessary. The concentrations of phenolic acids increased in the fertilized forage crops with the progress of the age of the plants. The concentrations were around 0.74 to 27.49 Âg mg-1 MS.

ASSUNTO(S)

leguminosas quimica clae legumes hplc compostos fenÃlicos association consÃrcio phenolic compounds gramÃneas grasses

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