Effects of substitution levels of corn by <em>citrus</em> pulp on apparent digestibility in feedlot bulls

Abstract

This experiment was carried out to study the apparent digestibility coefficient of dry matter, organic matter, crude protein, gross energy and neutral detergent fiber of four diets with different substitution levels (40%, 60%, 80% and 100%) of corn, as energy source, by citrus pulp fed to crossbreeding bulls (F1) in feedlot. Besides corn and/or citrus pulp, as energy source, the animals were fed with corn silage, soybean meal, meat and bone meal, as protein source, and bicalcic phosphate, limestone, mineral miture and monensin. Twenty-eight crossbreeding bulls with about 20 months of age and 346 kg of live weight were alocated in a complete randomized design, with four diets (citrus pulp levels) and seven replications. The animals were housed in 10m² pens and fed ad libitum. Insoluble acid ash was utilized as internal indicator. Remainder and feces were collected from all animals in the pens with a long spoon for 7 days, after 28-day adaptation. The dry matter, organic matter, crude protein, gross energy and neutral detergent fiber digestibility apparent coefficients for diets with 40% and 100% of citrus pulp were similar and higher than the values obtained for substitution levels of 60 and 80%. Thus, the best equations to describe the apparent digestibility coefficients for substitution levels of corn by citrus pulp were the quadratic ones.