The enteric methane mitigation potential of 3-nitrooxypropanol (3-NOP) has been confirmed in previous studies, and new research published in the Journal of Dairy Science examines the dose-response effects of 3-NOP on enteric methane emissions in dairy cows

According to an announcement from the journal, 3-NOP is highly soluble and rapidly metabolized in the rumen. Previous studies have shown a persistent methane mitigation effect when 3-NOP is administered through the total mixed ration (TMR).

After a 14-day adjustment period, 49 multiparous Holstein cows at The Pennsylvania State University's Dairy Teaching & Research Center received a base TMR mixed with a placebo or one of six treatment doses ranging from 40 to 200 mg of 3-NOP per kilogram of feed.

Dose levels were chosen based on previous research at Penn State as well as studies conducted in beef cattle. The researchers hypothesized that within the range of application rates studied, 3-NOP would decrease enteric methane emissions without affecting dry matter intake or the lactational performance of the cows, the announcement said.

The researchers reported that including 3-NOP in the TMR quadratically decreased daily enteric methane emissions by 22-40% in lactating dairy cows, with an average reduction of 31%. In this experiment, 3-NOP had no effect on dry matter intake or milk yield but linearly increased milk fat concentration and yield, the researchers determined.

"We can determine by calculation that the decrease in daily enteric methane emissions would have increased the availability of feed digestible energy," said lead investigator Alexander Hristov with the department of animal science at Penn State. "The reduction in emitted methane with 3-NOP would represent, in theory, additional energy for lactation that could potentially be used for productive purposes."

The results of this study suggest that 3-NOP is a promising feed additive for reducing enteric methane emissions while maintaining lactational performance in dairy cows and potentially increasing milk fat yield, the researchers said.