GLYCEROL INCLUSION LEVELS IN CORN AND SUNFLOWER SILAGES Níveis de inclusão de glicerol nas silagens de milho e girassol

Due to the seasonal cycle of forage, the use of silage to feed animals provides nutrients throughout the year. However, its quality can be improved with the inclusion of additives and other products. Glycerol is a rich source of energy and present a high efficiency of utilization by animals. The purpose of this work was to evaluate the effect of glycerol inclusion on the chemical and fermentation characteristics of corn and sunflower silages. Two silage sources (maize and sunflower) were used and four levels of glycerol inclusion (0, 15, 30 and 45%) based on dry matter were carried out. The experimental design was completely randomized in a 2 x 4 factorial arrangement with five replications. The pH values and chemical composition of corn and sunflower silages were determined. In both silages there was increment of dry matter, non-fiber carbohydrates and total digestible nutrients (TDN) added to a reduction of crude protein, neutral detergent fiber and acid detergent fiber due to the glycerol inclusion. The corn silage required 45 % glycerol to achieve the TDN level of the sunflower silage. The glycerol addition contributed to the increase in the nutritional value, offsetting loss of quality in the ensiling process. Index terms: Crude glycerin, biofuels, dry matter, fermentation quality, conserved forage. RESUMO Em decorrência do ciclo estacional das forrageiras, o uso de silagem na alimentação animal permite o suprimento de nutrientes durante o ano todo. No entanto, sua qualidade pode ser melhorada com a inclusão de aditivos e outros produtos. O glicerol constitu