Evaluating the impact of 3-nitroxypropanol supplementation on enteric methane emissions in pregnant non-lactating dairy cows offered grass silage

Abstract

Although 3-nitroxypropanol (3-NOP; Bovaer10®) has been proven to reduce enteric methane (CH4) by ∼30% in indoor systems of dairying when the additive is mixed throughout a total mixed ration (TMR), there has been limited research to date on the CH4 abatement potential of 3-NOP when mixed within a perennial ryegrass silage only based diet and fed to pregnant nonlactating dairy cows. To investigate the effect of 3-NOP supplementation on enteric CH4 emissions of pregnant nonlactating dairy cows, an 6-week study was undertaken in which treatment cows were supplemented with 3-NOP mixed within grass silage, while control cows were offered grass silage without additive supplementation. Enteric CH4, hydrogen (H2) and carbon dioxide (CO2) were measured using a GreenFeed machine. Body weight (BW), body condition score (BCS), dry matter intake (DMI) and calf birthweight were monitored to determine the effect of 3-NOP supplementation on productivity. The measured dietary concentration of 3-NOP was 63 (range 53.2 - 77.1) mg / kg DM. There was no effect of 3-NOP supplementation on any of the production parameters. Cows supplemented with 3-NOP produced 22% less enteric CH4 per day and CH4 per kg DMI, respectively (P < 0.001) than cows offered the control diet. Cows supplemented with 3-NOP also produced 4.4 fold more H2 and H2 per kg DMI, respectively (P < 0.001) relative to the control. Supplementing pregnant nonlactating dairy cows with 3-NOP during the winter housing period effectively reduced enteric CH4 emissions without detriment to productivity.