Degradabilidade in situ de silagens de sorgo com e sem taninos nos grãos

Abstract

The experiment was carried through at Experimental Farm of UNIMONTES in Janaúba, Minas Gerais in order to evaluate in situ degradability and the kinetic degradation of dry matter, crude protein, neutral detergent fiber and acid detergent fiber of silages of four sorghum genotypes, with presence and absence of tannin in the grains. They were used, two isogenic lines of grain sorghum (CMS-XS 114 with tannin and CMS-XS 165 without tannin) and two sorghum hybrids (double purpose, BR-700, with tannin and forage, BR-601, without tannin). The plantation of the genotypes was carried through in summer/2009, in seedbeds of 5 m of length, 3 m of width and spacing of 75 cm between lines. After the cut, the material was ensilaged. After the opening of the silos the samples were pre-dried, worn out and conditioned in glass bottles for analyses of dry matter, crude protein, neutral detergent fiber, acid detergent fiber, hemicelluloses, cellulose and lignin, pH, NH3/NT and in situ digestibility of the dry matter. The used experimental design was entirely at random, with four repetitions and four treatments and the averages compared by the Tukey test with the level of 5% significance. As for degradation rate of DM, the ensilage of CMSXS165 line without tannin was superior to all of the treatments. The isogenic line genotype without tannin (CMSXS 165) presented greater effective degradability of CP than the line with tannin (CMSXS 114). The ensilages of genotypes BR700 and CMSXS 114 with tannin presented the highest values of non digestible fraction of ADF (59.54 and 43.09%), respectively. For the NDF, it was observed that the potential of degradation of the ensilage of line CMSXS165 without tannin was superior to all of the treatments. Line BR700 was similar to 114 CMSXS one and inferior to BR 601 one. Thus, the results found in this experiment allow concluding that the presence of the tannin can reduce the rumen degradability of the dry matter, crude protein and fiber fractions of the ensilages.