Productive performance of confined young bulls fed proportions of 'Mulato II' grass silage in the diet

Abstract

The objective of this work was to evaluate the performance of young Nellore bulls and of young dual-purpose dairy bulls fed proportions of 'Mulato II' grass silage (400 and 100 g kg-1), in diets with high levels of concentrate, as well as to evaluate the cost of this feed. Sixteen young Nellore bulls and 16 young dairy crossbred bulls were used, with initial average weight of 380.69±10.45 and 376.94±17.16 kg, respectively, and average initial age of 24 months. A completely randomized experimental design was carried out in a 2×2 factorial arrangement. The highest silage proportion caused a 13% increase in dry matter intake (percentage of body weight) and a 19.7% decrease in dry matter digestibility of the diet, but it did not alter the intake of total digestible nutrients, nor the average daily gain or carcass characteristics. Nutrient intake and digestibility, average daily gain, and carcass characteristics (except conformation) did not change due to the genetic group of animals. Feed conversion was 18.3% better in young dairy bulls. In diets with high levels of concentrate, the proportion of 400 g kg-1 of 'Mulato II' grass silage, in comparison with that of 100 g kg-1, does not affect the productive performance, nor the main carcass characteristics of economic interest of confined young bulls, but reduces feeding costs.