Effects of various feed additives on the methane emissions from beef cattle

The objective of this study was to identify feed additives that reduce methane emitted from growing beef cattle fed high forage diets. We measured enteric methane for 72 h in three experiments using whole animal chambers. Exp. 1 and 2 used Holstein steers (311.6 ± 12.3 kg), whereas Exp. 3 used Angus heifers (260 ± 32 kg). The basal diet consisted of 75% whole crop barley silage (dry matter basis, DM). Treatments were: control (no additive), unsaturated fats (sunflower oil, 50 g/kg DM; canola oil, 46 g/kg DM), monensin (33 mg/kg DM), proteolytic enzyme (1 mL/kg DM), fumaric acid (12 and 29 g/kg DM), essential oil (161 mg/kg DM), and yeast (Levucell, 149 mg/kg DM; Procreatin, 536 mg/kg DM). Sunflower oil reduced methane emissions per unit of gross energy (GE) intake by 22%, with 25% of this reduction attributed to a decline in diet digestibility. Canola oil reduced methane emissions per unit of GE intake by 21%, but 70% of this reduction was due to a depression in diet digestibility. Monensin reduced methane emissions by about 9% without reducing diet digestibility. None of the other products tested reduced methane emissions in a statistically significant manner, although a numerical (3%) reduction in methane was observed for Procreatin yeast which requires further evaluation. This study demonstrates that diet modification can be used by the cattle industry to reduce its greenhouse gas emissions. Of the ingredients tested, sunflower oil and monensin offer the greatest reductions in methane without substantial reductions in diet digestibility.