Effect of sugarcane treated with non-protein nitrogen and hydrolyzed with calcium oxide in the diet of dairy steers

Abstract

This study examines the effect of sugarcane hydrolyzed with calcium oxide (quicklime) associated with non-protein nitrogen (a mixture of urea and ammonium sulfate) on nutrient intake, rumen degradability and kinetics, intestinal digestibility and blood and urinary parameters in dairy steers. The treatments consisted of fresh sugarcane (Sc); fresh sugarcane with urea (ScUr); sugarcane hydrolyzed with quicklime (ScQl); and sugarcane hydrolyzed with quicklime plus urea (ScUrQl), maintaining a roughage:concentrate ratio (DM basis) of 70:30. Four rumen-cannulated Jersey steers were used in a Latin square design for data collection. The animals were fed the respective diets for 72 days. Mineral matter intake differed across the treatments, with higher values obtained with the treatments containing quicklime. The average mineral matter intake was 0.27, 0.22, 0.54 and 0.48 kg day-1 for the Sc, ScUr, ScQl and ScUrQl treatments, respectively. Short-chain fatty acid and ammoniacal nitrogen concentrations, pH, rumen-fluid kinetics and potential degradability of DM (''a'' + ''b'' fractions) were not influenced by the additives. The diets containing quicklime provided an increase in calcium absorption, which averaged 18.7, 21.3, 25.8 and 26.5% for the Sc, ScUr, ScQl and ScUrQl treatments, respectively. Serum nitrogen levels were higher in the animals fed urea, averaging 12.3, 20.4, 15.3 and 21.1 mg dL-1 urea for the Sc, ScUr, ScQl and ScUrQl treatments. However, urinary glucose and nitrogen excretion levels did not differ significantly. Hydrolysis with quicklime and the inclusion of urea in sugarcane promote increases in intake, absorbed calcium and plasma nitrogen levels.