Adição crescente de ureia na cana de açúcar (SACCHARUM OFFICINARUM L.) in natura em dietas de vacas em lactação

Abstract

Two experiments were conducted to evaluate the effect of adding increasing levels of urea 0.0, 0.5 and 1.0% to a sugar cane as feed basis, on milk prodution and composition, blood metabolites, rumen fermentation, digestion kinetics, protozoa populations and economicviability. In the first experiment, three lactating cows, rumen cannulated, averaging ± 20.76 kg of milk per day, and ± 87 days in milk were used in Latin Square desing. In the second experiment, 18 lactating, with ± 21.3 kg of milk per day, and ± 83 days in milk, allotted to a cross over in a 3x3 switch-back desing. The average rumen pH off 6,33 provideda a suitable environment for the rumen fermentation, and the ciliate protozoapopulation specially genus Entodinium the most prevalent of the rumen ciliates. The addittion of 1.0% of urea in on sugar cane, as feed basis, reduced the consumption of dry matter (DM) and organic matter (OM). The intake for DM and OM for diets containing 0, 0.5 and 1.0% of urea were 19.64, 19.66 and 18,33 kg d-1 and 18.24, 18.31 and 17.03 kg d-1,respectively. Feed efficiency (milk production / DM intake) was better for diets with urea, however, productive and metabolic parameters did not differ among diet. Considering only the feed cost all diets showed a positive balance.