Enteric methane (CH4) production is the main source of greenhouse gas emissions from livestock globally with beef cattle contributing 5.95% of total global greenhouse gas emissions. Various mitigation strategies have been developed to reduce enteric emissions with limited success. In vitro studies have shown a reduction in CH4 emissions when using garlic and citrus extracts. However, there is paucity of data regarding in vivo studies investigating the effect of garlic and citrus extracts in cattle. The objective of this study was to quantitatively evaluate the response of Angus × Hereford cross steers consuming the feed additive Mootral, which contains extracts of both garlic and citrus, on CH4 yield (g/kg dry matter intake [DMI]). Twenty steers were randomly assigned to two treatments: control (no additive) and Mootral supplied at 15 g/d in a completely randomized design with a 2-wk covariate and a 12-wk data collection periods. Enteric CH4 emissions were measured using the GreenFeed system during the covariate period and experimental weeks 2, 6, 9, and 12. CH4 yield (g/kg DMI) by steers remained similar in both treatments for weeks 2 to 9. In week 12, there was a significant decrease in CH4 yield (23.2%) in treatment compared to control steers mainly because the steers were consuming all the pellets containing the additive. However, overall CH4 yield (g/kg DMI) during the entire experimental period was not significantly different. Carbon dioxide yield (g/kg DMI) and oxygen consumption (g/kg DMI) did not differ between treatments during the entire experimental period. DMI, average daily gain, and feed efficiency also remained similar in control and supplemented steers. The in vivo results showed that Mootral may have a potential to be used as a feed additive to reduce enteric CH4 production and yield in beef cattle but needs further investigation under various dietary regimen.

Several in vitro fermentation studies had demonstrated the efficacy of Mootral, a patent-pending natural feed supplement, in reducing methane gas production. In order to test the supplement's application in a commercial farm, Jersey (n = 121) and Holstein-Friesian (HF, n = 275) lactating cows received 500 g of pellets containing 3% Mootral powder for 12 weeks. Their enteric methane gas production was monitored using a hand-held laser methane detector. During 7 weeks of pre-Mootral supplementation period, dry matter intake (DMI), milk yield and milk quality (fat, protein, urea, pH, bulk tank somatic cell count (BTSCC)) were monitored for both herds and continued during 12 weeks of Mootral supplementation (Mootral period), and 4 weeks after withdrawal of Mootral (post-Mootral period). Feed samples were analysed during each period, and feed efficiencies (FE) for each herd were calculated. Compared to the baseline, the methane gas produced by the Jersey and HF cows during the Mootral period were lower by 38.3% and 20.7% (p < 0.05), respectively. DMI for Jerseys were greatest during the pre-Mootral period (p < 0.05), while no difference was recorded for the HF cows. Milk yield increased significantly (p < 0.05) for both herds during Mootral supplementation. FE increased significantly for the Jersey herd during the Mootral and post-Mootral periods (p < 0.05). Statistically significant changes were detected for urea in both herds, and BTSCC for HF cows, but these did not adversely affect milk quality. Results demonstrated Mootral reduces enteric methane production in lactating cows while increasing milk yield without affecting milk quality.