Successfully reducing emissions in the dairy sector
Dairy farmers accept and understand that they have a key role to play in reducing their herd’s emissions. Farmers know there are a number of measures they can implement, from smarter breeding and management to AI tools, to help reduce greenhouse gases production from livestock.
As science intensifies and new research becomes available, dairy farmers are willing to embrace the new knowledge and apply it to their farms. Adjusting feed, both in concentrate form and grass, can help reduce the overall amounts of gases cows produce. Various research projects have studied how reducing the protein content of a cow’s diet affects the volume of methane produced.
Studies show that cows can be fed around 10% less protein without it negatively affecting health or milk production. This can be achieved, for example, by reducing the protein content of the concentrates that cows consume and increasing the amount of maize silage fed.
Research carried out at Wageningen University and Research in the Netherlands looked at roughage in the diet and measured the methane produced in special respiration chambers. These trials found that it was more beneficial to feed cows grass silage made from shorter, leafier grass than grass mown at a later stage of growth. Harvesting grass at later stages of growth produced silage that was stiffer and more difficult to digest. Feeding young grass or young grass silage resulted in up to 30% fewer methane emissions. On the flip side, young grass does contain a lot of nitrogen, so it is important to reduce the nitrogen content in the rest of the cows’ diet if going this route.
Feeding more maize silage was found to be one of the better methods of reducing methane and ammonia levels produced by cows. As maize silage is low in protein, it provides starch which partially bypasses the rumen, producing less methane, while it is converted into glucose in the small intestine providing energy for the cow. This process improves nitrogen utilisation in the cow, so less nitrogen ends up in the cow’s urine.
Smarter breeding
There is a general consensus that smaller cows naturally produce less methane, potentially due to differences in the microbial communities within their digestive systems. Research at the University of Pennsylvania School of Veterinary Medicine in the US identified key differences between cows that naturally emit less methane than average. The scientists found that differences in methane emissions were accompanied by differences in microbial populations as well as their fermentation pathways.
The researchers said: “Low methane emitters are more efficient cows. Methane formation is an energy-inefficient process, so reducing methane production gives that energy back to the cow to use for metabolic activities, including improved growth rate and milk production.”
The team’s goal was to breed animals that naturally emit less methane. Cows naturally vary in how much methane they emit, and prior studies suggested that this variation is partially heritable. The scientists first identified 5 low-methane-emitting cows and 5 high-methane-emitting cows from a herd of 130 lactating Holstein cows housed at Penn State. They then set out to characterise the differences between these low and high emitters based on their genetics, milk production, rumen fermentation, and rumen microbiomes.
On average, the low emitters produced approximately 22% less methane than high emitters, corresponding to 126 kg of methane per year per cow instead of 160 kg per year. Overall, there was no difference between low and high methane emitters in terms of food intake, amount of milk produced, or milk composition, though low methane emitters did digest less of the food they consumed.
However, there were major differences in the rumen microbes and fermentation patterns of the low and high-methane-emitting cows, because methane is produced via microbial fermentation. Low-methane-emitting cows housed fewer types of microbes in their rumens, and their microbes were less likely to be methane producers or methanogens. When the researchers compared the gene expression of ruminal microbes in low versus high emitters, a measure of how often the microbes are using these genes, they found that low emitters had lower levels of methyl-CoM reductase, an enzyme involved in methane formation. Low-methane-emitting cows also tended to have smaller statures than high emitters.
Going forward, the team is investigating whether it is possible to selectively breed dairy cows to have efficient microbiomes. To further reduce methane emissions, these results could be combined with other management strategies, for example, by feeding synthetic or algal methane inhibitors to low-methane-emitting cows.
Advances in AI tools
Computer scientists at the UK’s Loughborough University have developed AI tools that offer insights into how greenhouse gas emissions associated with livestock farming and land use can be reduced. These tools, which are hosted on an online digital platform, aim to provide farmers, farming organisations, and government bodies with data on how changes in livestock practices and land use can help the UK achieve its 2050 net-zero goal.
Key features of the platform, developed by a team led by Professor Baihua Li and Professor Qinggang Meng, include machine learning models designed to estimate methane emissions from livestock farming, predict milk productivity and ammonia emissions from dairy farms, and analyse how land use and environmental factors influence methane emissions across the UK.
Professor Li: “Our mission is to bridge the gap between innovation and practical tools by offering a platform that supports data-driven decisions to combat climate change, advance sustainable farming, and achieve global net-zero emissions goals. By harnessing AI, our platform can offer data-driven insights that can help forecast future emissions based on a diverse range of data, giving stakeholders actionable intelligence to make cost-effective proactive decisions.”
Using diverse livestock and environmental datasets, Loughborough University’s AI models analyse how various factors interact to impact emissions, providing farm-level and nationwide insights that can help shape strategies to support the UK’s net-zero goal. The tools’ design means farmers simply input details about their specific animals and practices to estimate their current annual greenhouse gas emissions. They can then explore potential changes to their management practices by selecting options from drop-down menus or entering variable values. These adjustments provide immediate insights into their potential impact on both emissions and farm productivity.
One tool is designed specifically for dairy farmers and helps estimate how their current practices affect individual cow milk yield and ammonia levels in waste.
The research has shown that methane emissions have been increasing. The next stage for the researchers is to further refine and test their AI models, for which additional data and funding is needed before the tools can be released.
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