So following on from the other blog this week on research that has been taking place in the UK looking at dietary strategies to reduce GHG emissions from livestock, it seems like a good idea so see what other clever scientists around the world are looking at. As nutrition and strategies for reducing emissions from livestock are so important, not surprisingly there has been a great focus into seeing whether there are any magic compounds or feeding strategies that can help address the emissions concerns.
The info below brings you details of a few research projects that have been going on, mainly from Australia, America and Canada. Under current welfare laws here, some of the practices that have been trialled abroad may not be replicable in UK conditions.
Nutritional mitigation of methane production is founded on three basic approaches:
- Ingredient selection to alter volatile fatty acid (VFA) production patterns
- Increased rate of passage which can alter the microbial populations and VFA production patterns and shift some digestion to the intestines
- Feeding better quality diets to increase milk production per cow which dilutes the methane costs associated with maintenance energy requirements
What’s going on down under?
Researchers are studying novel feed supplements, pasture forages and pre-treatment of cereal based grains for use in livestock feeding, quantifying the impacts on both methane emissions and animal production.
In the lab
They have been comparing perennial and summer active annual forages, maximum gas was produced in forages containing more fermentable organic matter. They have also compared different forages harvested at different times over winter, spring, and summer, which showed that pasture species has a greater influence on the amount of gas produced than did the date of harvest. Other studies have looked at pre-treating wheat with different products to suppress methane production in the rumen.
Studies in cattle
Using dairy cattle, the researchers compared different what dosages in the ration. The results showed a linear decrease in methane emissions in response to greater amounts of wheat as well as a linear increase in milk yield.
Trials are currently underway looking at the effect of forages and supplements. Supplements that have been trialled in Australia include grape products and the effects of including chicory, plantain and brassicas in the ration.
Research in America
Type of carbohydrate fed
Greater dry matter intake with higher milk yields and lesser methane yields are often achieved by feeding more digestible carbohydrates. Cows fed increasing amounts of dried distillers grains rather than corn emitted less methane that those fed corn based rations.
Forage quality, species, harvesting and storage
Increasing forage quality and feeding high quality forages is central to good farming practices and often increases profitability. Different additives and inoculants have been added to silage with limited success in reducing methane production.
In the UK research is currently underway at Aberystwyth looking at the use of high sugar grasses as a tool to reduce methane production per litre of milk produced.
In the lab, many additives and inhibitors suppress methane production by 60-100%. However when these additives are fed to animals however, the reduction in methane emission has either not been evident or only transient.
To date no feed additives have demonstrated sustained reduction in methane emissions without a negative effect on milk production in lactating dairy cattle other than the use of nitrate, which has issues with animal toxicity.
At this time greater opportunities exist in reducing enteric CH₄ emissions from dairy cows through nutrition, feeding management, genetic selection and improvements in herd health and productivity. More research is needed!
Rumen modifiers such as ionophores improve dry matter intake efficiency and suppress acetate production which results in reducing the amount of hydrogen released. In some of the published research, CH₄ has been reduced by 10%, however the effect of the ionophores has been short lived in respect to methane production. Research is ongoing.
Feeding fats and lipids
Dietary fats have the potential to reduce methane by up to 37%. This occurs through bio hydration of unsaturated fatty acids, enhanced proprionic acid production and protozoa inhibition. The effects are variable and lipid toxicity to the rumen microbes can be a problem. This strategy can however affect milk components and result in reduced income.
Condensed tannins can reduce methane production because they have a directly toxic effect on methanogens. However even at relatively low concentrations in the diet, condensed tannins suppress seed intake, reduce diet digestibility and reduce milk production.
It is the condensed tannins in some legumes that make them bloat safe, and there have been breeding efforts since the early 1990s to increase the tannin content of these species to reduce their potential to cause bloat in grazing cattle. These bloat safe legumes might also act to reduce methane production.