Rumen modifiers fail to cut cattle methane

Rumen modifiers have had very little success in terms of sustained methane reduction, without compromising milk production, according to researchers looking at how to help dairy farmers become more sustainable by reducing greenhouse gas emissions.

Globally, greenhouse gas emissions (GHG) from agriculture are 10-12% of man-made GHG emissions. according to 2010 figures.

But Ireland’s emissions profile is unique in the dominance of the agriculture sector. Agriculture, energy and transport accounted for 73% of Irish GHG in 2012, but agriculture alone accounted for 32% .

Between now and 2020, emissions from the agriculture and transport sectors — even under the best case scenario — are projected to increase by 15% and 9%, respectively.

Ireland’s EU target is to reduce GHGs 20% by 2020 (compared to 2005). But Environmental Protection Agency projections show emissions remaining relatively static up to 2020, at only 5-12% below 2005 levels.

“We are currently not on track to becoming a low-carbon economy,” said Laura Burke, Director General of the EPA.

“We need to translate our national commitment to a low-carbon future into action on the ground if we are to deliver the required emission reductions. There are wide benefits for business and farmers, for example, which include reducing impacts and costs; managing and minimising risk more effectively and building competitive advantage through innovative products and processes.” For our dairy sector, there is no silver bullet, according to research findings gathered for the Journal of Dairy Science, the official journal of the American Dairy Science Association, rated the leading general dairy research journal in the world.

According to their appraisal, the wide variety of supplements that can be administered to reduce methane emissions by cows have not been a success. Chemical inhibitors, organic acids, and plant secondary compounds have failed — although there has been some success with nitrates. In lab conditions, many additives and inhibitors suppressed methanogenesis by 60-100%, but the reduction in methane emissions was either not evident or transient when these additives are fed to animals.

However, many other opportunities exist to reduce enteric methane and other GHGs from ruminant livestock, according to the Journal of Dairy Science. Research over the past century in genetics, animal health, microbiology, nutrition, and physiology has led to improvements in dairy production, where intensively managed farms have GHG emissions as low as 1kg of carbon dioxide equivalent, compared with over 7kg in extensive systems.

Nutrition and feeding approaches may be able to reduce GHGs by 2.5 to 15%. Reductions of 15 to 30% can be achieved by combinations of genetic and management approaches, including improvements in disease and fertility management, performance-enhancing technologies, and facility design to increase feed efficiency and life-time productivity of individual animals and herds.

Genetic selection for feed efficiency, heat tolerance, disease resistance, and fertility can augment selection for milk yield, with the potential of 9 to 19% GHG reduction

Feeding and nutrition have modest (2.5 to 15%) potential in intensive dairy operations in developed countries. Impacts of feeding and nutrition will be mostly achieved by improving feed efficiency.

Improvements in heat detection, heat synchronization, prevention of early embryonic death, and transition cow health would improve reproduction, reduce the number of cows culled due to poor reproduction and disease, and reduce the number of replacement animals needed. These management approaches could reduce GHGs by 9-19%. Vombined genetic and management approaches can reduce GHGs 15-30% in intensively managed dairy production systems that are already achieving high animal performance, according to the Journal of Dairy Science.