Methane is produced by bacteria during normal digestion of feed in the cow’s rumen and hindgut. As such, there is a strong relationship between the amount of feed eaten and methane produced. However, there is evidence to suggest that this relationship can be altered by improving efficiency – that is, reducing emissions per unit of feed eaten. Below, we look at key areas of research being conducted in New Zealand to improve emissions efficiency.
AgResearch’s sheep-breeding programme has confirmed that some animals emit less methane than others, and the trait is heritable. The research has developed two sheep lines that differ in methane yield (g CH4/kg DM eaten) by 11 percent1.
The research is now being extended to dairy cattle, with the establishment of a NZ Dairy Genetics collaborative working group, including DairyNZ researchers, to develop breeding options for low-methane-emitting cattle.
Diets of forage rape and fodder beet yield 20 and 30 percent less methane per kg of dry matter intake (DMI) than ryegrass pastures2. Research is extending to other forages.
Preliminary studies indicate methane yield is reduced when plantain is included at about 45 percent of a perennial ryegrass dominant diet3. Upcoming DairyNZ and AgResearch experiments will test these results.
Two species of methanogenic bacteria are responsible for 70 percent of methane produced. An AgResearch-led programme is aiming to develop a vaccine that targets and supresses the activity of these species to reduce methane emissions by at least 30 percent.
A collaborative project funded by PGgRc4 is investigating chemical inhibitors that suppress growth of methanogens and methane production in sheep and cattle by at least 30 percent. DairyNZ is involved in evaluating potential inhibitors for methane emissions and product quality.
Meanwhile, Dutch company DSM Nutritional Products has developed a feed additive, Bovaer®, that contains the methane inhibitor (3-NOP). Bovaer® successfully reduces methane emissions from livestock fed a total mixed ration. Research continues with this product to evaluate its applicability and efficacy in a pasture-based system.
- NZAGRC. 2019. NZAGRC Annual Report 2019, Wellington, New Zealand. https://www.nzagrc.org. nz/page-2019,listing,598,annual-report-2019.html
- Sun, X., D. Pacheco, and D. Luo. 2016. Forage brassica: a feed to mitigate enteric methane emissions? Animal Production Science 56: 451-456.
- Minneé, E. M. K., C. A. M. de Klein, and D. E. Dalley. 2019. Plantain helping farmers to achieve environmental targets. DairyNZ Technical Series:5-8.
- NZAGRC and PGgRc. 2017. Reducing New Zealand's Agricultural Greenhouse Gases: Methane Inhibitors. Factsheet. https://www.pggrc.co.nz/
This article was originally published in Technical Series April 2020