Intake, performance, digestibility, microbial efficiency and carcass characteristics of growing Nellore heifers fed two concentrate levels

The objective of this study was to evaluate nutrients and dry matter intake, average daily gain, feed efficiency and digestibility of diets, microbial efficiency, cold carcass yield and basic cuts yields of young Nellore heifers receiving two concentrate levels. Nineteen heifers with initial average weight of 165.6±29.8 kg were used. Three animals were used in a trial to determine the digestibility and microbial efficiency of the two levels of concentrate (225 and 450 g/kgDM) and a treatment with a restricted intake maintenance level. The remaining 16 heifers were confined for 168 days for evaluation of performance and intake, divided into two levels of concentrate. Every 42 days, four animals, two from each concentrate level, were slaughtered to determine carcass characteristics, making a 2 × 4 factorial arrangement. Digestibility and microbial efficiency were not affected by concentrate level or intake level, both for ad libitum and restricted feeding. Heifers fed 450 g/kgDM concentrate diet had greater average daily gain than those fed 225 g/kgDM concentrate. Dry matter intake and feed efficiency did not differ between levels of concentrate. Average daily gain (kg/day), dry matter intake (% body weight/day) and feed efficiency were higher in the first period of feedlot (0-42 days) compared with the other (42 to 168 days). Heifers fed 450 g/kgDM concentrate had greater average daily gain than those fed 225 g/kgDM concentrate.