Including essential oils in lactating dairy cow diets: Effects on methane emissions¹

The objective of this study was to examine the effects of dietary supplementation of garlic and juniper berry essential oils on methane (CH4) and carbon dioxide (CO2) emissions from lactating dairy cows. Four ruminally cannulated, lactating Holstein cows were used in a 4 × 4 Latin square (21-day period; 11 days of adaptation). Cows were fed a total mixed ration (60:40 forage:concentrate ratio) without supplementation (no additive; negative control) or supplemented with monensin (330 mg/day; positive control), garlic oil (5 g/day) or juniper berry oil (2 g/day). Methane and CO2 emissions were measured using the sulfur hexafluoride tracer technique. Dietary supplementation of lactating cows with juniper berry oil or garlic oil did not affect (P > 0.05) CH4 or CO2 production, whether expressed as g/day, g/kg DMI, g/kg milk or as g/kg DMI/BW0.75. At the doses administered in this study, the anti-methanogenic effect of garlic and juniper berry oils previously observed in vitro were not confirmed in vivo. © CSIRO 2014.