Padrão fermentativo e composição química das silagens de BRS-Capiaçu e de cana-de-açúcar aditivadas com coprodutos de cervejaria e de destilaria

Abstract

Agro-industry by-products have been used in the form of absorbent additives to increase the dry matter (DM) and water-soluble carbohydrate content of grass ensiling in order to improve the fermentation pattern and nutritional value of the silage produced. The aim of Experiment I was to evaluate the fermentation pattern, losses and chemical composition of elephant grass silage supplemented with brewery residue. The experimental design was entirely randomized, with three replications. The treatments were arranged in a 2x4 factorial design, as follows: two types of brewery residue (wet: WBW; pre-dried: PdBW); four levels of inclusion in the forage mass of BRS Capiaçu elephant grass (0; 10; 20; 40%) and in the forage mass of BRS Capiaçu elephant-grass. The variables measured were dry matter content (DMfor) and buffer capacity (BC) of the forage; pH, ammoniacal nitrogen (NH₃-N), loss by gases (LG) and effluents (EL), recovery of dry matter (RDM), dry matter content (DMSil), ash, crude protein (CP), neutral detergent fiber (NDF), acid (ADF) and total digestible nutrients (TDN) of the silage. At all levels of inclusion (10, 20 and 40%), PdBW provided higher levels of DMFor, DMSil and CP, and lower levels of BC and EL, than WBW. Compared to WBW, lower N-NH3 and LG contents were obtained with the use of PdBW at the 10 and 40% inclusion levels. On the other hand, higher TDN and lower NDF and ADFD contents were obtained with the use of PdBW instead of WBW at the 20% inclusion level. When WBW was used, there was a decreasing linear effect of the inclusion levels on the MSSil, NDF, ADF and LG contents. On the other hand, there was an increasing linear effect of inclusion levels on the levels of CP, TDN and EL. There was no adjustment for DMFor (31.87%) and RDM (93.08%). When using PdBW, there was a quadratic effect of inclusion levels for all the variables, with the exception of pH (decreasing linearly) and RDM (increasing linearly). The pre-dried brewery residue promotes a good fermentation pattern in the silage mass, improving the chemical composition and reducing losses in the production of elephant grass silage. The inclusion of 18.43% pre-dried brewery residue in elephant grass silage is recommended. In Experiment II, the aim was to determine the fermentation pattern, losses and chemical composition of sugarcane silage supplemented with wet distillers grains (WDG). The experimental design was entirely randomized, with four replications. The treatments consisted of six levels of WDG inclusion (0; 5; 10; 15; 20 and 30%) in the forage mass of sugar cane cultivar RB 036152 (medium-late cycle). The variables measured were dry matter content (DMfor) and buffer capacity (BC) of the forage; pH, ammoniacal nitrogen (NH₃-N), loss by gases (PG) and effluents (EL), dry matter recovery (RDM), dry matter content (DMSil), mineral matter (MM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), indigestible neutral detergent fiber (iNDF), total digestible nutrients (TDN) and in vitro dry matter digestibility (IVDMD) of the silage. There was a quadratic effect of the levels of WDG inclusion (p<0.05) on the levels of DMFor, BCFor, N-NH₃, DMSil, NDF, ADF, IVDMD and TDN. For the BCFor, DMSil and TDN variables, the maximum point estimates were observed at WDG inclusion levels of 17%, 17.58% and 9.46%, respectively. For the N-NH₃, NDF and ADF variables, the minimum point estimates were found at WDG inclusion levels of 21.35%, 9.48% and 24.25%, respectively. There was an increasing linear effect of the WDG inclusion levels (p<0.05) on the CP, RDM and iNDF contents (p<0.05). On the other hand, there was a decreasing linear effect of WDG inclusion levels for the iNDF content (p<0.05). There was no regression adjustment for pH, gas losses and effluents. The averages obtained were 3.16; 0.12% DM and 27.77 kg/t of green mass for pH, gas losses and effluents, respectively. The inclusion of 10% wet distillers grain (WDG) in sugar cane silage promotes a good fermentation pattern, does not influence losses and improves the nutritional value of the silage produced.