Methane emissions and growth performance of young Nellore bulls fed crude glycerine- v. fibre-based energy ingredients in low or high concentrate diets

A total of 70 Nellore bulls (18 ± 3 months of age) were used to determine the effects of crude glycerine (CG) replacing starch- v. fibre-based energy ingredients in low (LC; 0·40 concentrate) or high concentrate (HC; 0·60 concentrate) – on a dry matter (DM) basis – on DM intake (DMI), methane emissions and growth. Ten bulls were slaughtered (reference group) to obtain the carcass gain (CrG). The 60 remaining bulls (374 ± 24·5 kg) were allocated to a 2 × 3 factorial arrangement (two concentrate levels, LC or HC; and three feeding regimes, FR). The FR were: CO – without CG and maize as an ingredient of concentrate; CGM – inclusion of CG (0·10 of DM) replacing maize in the concentrate; and CGSH – inclusion of CG (0·10 of DM) replacing soybean hulls (SH) in the concentrate. Bulls fed LC or HC had similar DMI (kg/d) and growth. The DMI and average daily gain (ADG) were similar among FR. Concentrate level and FR tended to interact for methane emissions (g) per kg DMI. Bulls fed CGM had a greater G : F (g CrG/kg DMI) than those fed CO or CGSH diets. Increasing dietary concentrate (0·40–0·60) did not affect intake, methane emissions, or growth. Inclusion of CG in diets to replace SH in LC diets tended to decrease methane emissions from animals. When CG replaces SH in the diets, CrG and G:F (g CrG/kg DMI) are decreased compared with bulls fed CGM