Grão de soja tostado como suplemento para vacas Holândes X Gir em pastagem de Brachiaria brizantha cv. Marandu

Abstract

The objective was to evaluate the effect of increasing levels of roasted soybean seeds (RSB) in the diet on rumen In situ degradation of dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) of forage and rumen fermentation parameters (pH, concentration of volatile fatty acids and ammonia and rumen liquid phase passage rate of lactating cows grazing Brachiaria brizantha cv. Marandu. A 4 x 4 Latin square design with four rumen fistulated cows receiving concentrate with 0, 22, 43 or 65 % of RSB. For fermentation parameters study was used the Latin Square Split-plot design. Degradability data were estimated from grass samples, was used sample grass (12.6% DM, 10.8% crude protein-CP and 69.7% NDF) collected from a cow with esophageal cannula grazing the same pasture with the experimental animals. There was a linear effect (P<0.05) of sampling time on the rumen ammonia and propionate concentrations, and the molar proportion of propionate and butyrate, however no effect (P>0,05) of RSB levels on the rumen pH. No effects of (P> 0.05) RSB levels on the rumen degradation of DM, OM and NDF were observed. The range observed for degradation rate, potential and effective degradability of the forage were, respectively, 3.41 to 3.92%/h; 85.4 to 86.4% and 49.8 to 51.4%, for 0, 22, 43 or 65% of RSB in the concentrate. The addiction of RSB in the diet did not affected (P>0.05 the rumen liquid phase passage rate , turnover time , liquid turnover rate and flow rate, however showed a significant effect on the ruminal volume (P<0,05). The inclusion of up to 65% of RSB in the concentrate resulted only a small effect on both rumen fermentation parameters and degradation kinetics.