Enteric methane mitigation strategies through manipulation of feeding systems for ruminant production in Southern Australia

Summary

This project was undertaken as part of the National Livestock Methane Program (NLMP; 2012-2015) which coordinated national research to reduce methane emissions from livestock while increasing productivity.

When cattle and sheep (ruminants) digest feed in their rumen, they produce methane, which constitutes approximately 7% of the energy consumed. If this enteric methane could be reduced and the saved energy diverted to the production of meat or milk, this would enhance the productivity, efficiency and profitability of Australia’s livestock industries.

Previous Department of Economic Development, Jobs, Transport and Resources (DEDJTR) research into the use of dietary supplements to reduce enteric methane has, to date, provided the only practical and profitable mitigation strategies in Australia. In addition, significant capability has been developed in measurement and understanding of rumen gases.

The work undertaken in this project has focused on research to enhance productivity without substantially increasing methane emissions from ruminants.

Objectives

This project aimed to quantify the mitigation potential of a range of feeds and feeding strategies to provide new data for national inventories and the Carbon Farming Initiative (CFI) offset methodologies, while improving production efficiency by conducting:

• in vitro assessments of novel supplements, forages and pre- treatments of cereal grains
• in vivo assessment of novel supplements offered to dairy cattle
• in vivo assessment of the integration of novel supplements and forages offered to dairy cattle
• in vivo assessment of pre-treatments of cereal grains offered to sheep.

Key findings

Although almond hulls and citrus pulp can be used as a low cost feed supplement to support milk production in dairy cows, they are unsuitable as feed supplements intended to inhibit enteric methane emissions.

Refinements to methodologies (both in vitro and in vivo) have resulted in greater confidence in the data being generated from more cost effective scientific techniques, which in turn will provide greater opportunity for other research groups (nationally and internationally) to utilise such methods and screen other feed options.

Benefits to industry

This project has identified and quantified feed supplements, grain treatments and novel forages that enable improved strategies for enhancing milk and meat production while simultaneously reducing methane intensity and possibly greenhouse gas emissions. 

The knowledge generated from this project will be invaluable to the Australian dairy and livestock industries and dairy and livestock farmers in the temperate zone of Australia will benefit in the long term. Policy experts will have information to enable improved inventory techniques for estimating methane emissions.

MLA action

MLA has used this information to make decisions on the types of research required to bring profitable livestock methane mitigation studies to market. These investments are currently occurring as part of the Emissions Avoidance Partnership.

Future research

Research on the commonly fed supplement wheat, has raised the possibility of using this supplement at different feeding rates to significantly reduce methane emissions and intensity from dairy cows. However, based on data from this project it is suggested that further research be undertaken to further elucidate the mechanisms behind such reductions and in particular the influence of wheat type (starch and protein content) and forage structure (short and long chop length).