A supplement added to the feed of high-producing dairy cows can reduce methane emissions by 30 per cent and may have ramifications for global climate change, according to an international team of researchers.
In a 12-week study conducted at Pennsylvania State University's dairy barns, researchers also found that cows which consumed a feed regimen supplemented by the novel methane inhibitor 3-nitrooxypropanol - or 3NOP - gained 80 per cent more body weight than cows in a control group.
Significantly, feed intake, fibre digestibility and milk production by cows that consumed the supplement did not decrease, researchers said.
The findings are important because methane is a potent greenhouse gas. The US Environmental Protection Agency estimates that methane from livestock makes up 25 per cent of the total methane emissions in the US.
Fermentation in the rumen - one of the four stomach chambers of livestock such as cattle, sheep and goats - generates methane, as a result of microorganisms that aid in the process of digestion.
The 3NOP supplement blocks an enzyme necessary to catalyse the last step of methane creation by microbes in the rumen.
"We tested methane-mitigation compounds using animals with similar productivity to those on commercial farms because the nutrient requirements of high-producing dairy cows are much greater than those of nonlactating or low-producing cows," said lead researcher Alexander Hristov, professor of dairy nutrition at Penn State.
"Any reduction in feed intake caused by a methane-mitigation compound or practice would likely result in decreased productivity - which may not be evident in low- producing cows," he said.
Methane expulsion through burping represents a net loss of feed energy for livestock, Hristov noted, adding that a high-producing dairy cow typically emits 450 to 550 grammes per day of ruminal gas produced by fermentation.
The spared methane energy was used partially for tissue synthesis, which led to a greater body weight gain by the inhibitor-treated cows.
The 48 Holsteins in the study received varying amounts of the inhibitor in their feed and were observed at regular daily intervals over three months.
Their methane emissions were measured when the cows put their heads into feeding chambers that had atmospheric measurement sensors, and also through nostril tubes attached to canisters on their backs.
Scientists have tested many chemical compounds to inhibit methane production in ruminants. But the viability of the compounds as mitigation agents has been discounted due to concerns about animal health and food safety.
The 3NOP compound, developed by DSM Nutritional Products, a Dutch company, seems to be safe and effective, Hristov said.
If approved by the US Food and Drug Administration and adopted by the agricultural industry, this methane inhibitor could have a significant impact on greenhouse gas emissions from the livestock sector, Hristov said.
