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Feeding cows a few grams of seaweed daily can sharply reduce their contribution to climate change
A little seaweed with it? Cowirrie / Flickr, CC BY-SAMethane is a short-lived but powerful greenhouse gas and the second largest contributor to climate change after carbon dioxide. And the majority of methane emissions from methane come from livestock. About 70% of agricultural methane comes from enteric fermentation – chemical reactions in the stomachs of cows and other grazing animals when they degrade plants. The animals cut out most of this methane and give the rest as wind. There are about 1 billion cattle around the world, so reducing enteric methane is an effective way to reduce overall methane emissions. But most options to do so, such as adding the diet of cows to a more digestible feed or more fat, are not cost effective. In a 2015 study, it was suggested that the use of seaweed as an additive to the normal feed of cattle could reduce methane production, but this research was done in a laboratory, not in live animals. We study sustainable agriculture and focus on livestock. In a recently published study, we show that the use of red seaweed (Asparagopsis) as a feed supplement can reduce both methane emissions and feed costs without affecting meat quality. If these findings can be suspended and commercialized, it could transform cattle production into a more economical and environmentally sustainable industry. Cows’ special digestive system is an important methane brewer. Plant digestion machines Ruminants, such as cows, sheep and goats, can digest plant material that is indigestible to humans and animals with simple stomachs, such as pigs and chickens. This unique ability stems from the stomach with four compartments of ruminants – especially the rumen compartment, which contains a number of different microbes that ferment feed and break it down into nutrients. This process also generates by-products that are not absorbed by the cow’s body, such as carbon dioxide and hydrogen. Methane-producing microbes, called methanogens, use these compounds to form methane, which drives away the cow’s body. We analyzed this problem for the first time in a 2019 study, the first similar research done in cattle rather than in a laboratory. In the work we showed that the supplementation of dairy cows’ feed reduced about 10 grams of seaweed per day by up to 67%. However, the cattle that ate this relatively large amount of seaweed consumed less feed. This reduced their milk production – a clear disadvantage for dairy farmers. Our new study sought to answer several questions that would be important for farmers considering whether to use seaweed supplements in their cattle. We wanted to know if the seaweed was stable when stored for up to three years; or microbes that produce methane in cows’ stomachs can adapt to the seaweed and render it ineffective; and whether the type of diet the cows ate altered the effectiveness of seaweed in reducing methane emissions. And we used less seaweed than in our study in 2019. A driver eats lucerne grains while equipment measures his gas emissions, including methane. Breanna Roque, CC BY-ND Better growth with less feed For the study, we fed 21 to 1.5 grams of seaweed per animal daily to 21 beef cattle cows for 21 weeks. As with most new ingredients in livestock diets, it took a while before the animals got used to the taste of seaweed, but they got used to it within a few weeks. Cattle in the study quickly adapt to the addition of seaweed in their food. Breanna Roque, CC BY-ND As we expected, the steering released a lot of hydrogen – up to 750% more, mostly from their mouths – because their systems produce less methane. Hydrogen has a minimal impact on the environment. Seaweed supplements have no effect on the animals’ carbon dioxide release. We also found that seaweed that had been stored in a freezer for three years retained its effectiveness, and that microbes in the digestive systems of the cows did not adapt to the seaweed to neutralize its effects. We fed each of the animals three different diets during the experiment. These rations contain varying amounts of dried grasses, such as lucerne and wheat hay, which are referred to as feed. Cattle can also consume fresh grass, grains, molasses and by-products such as almond hull and cotton seed. Methane production in the rumen increases with increasing feed levels in the cows’ diet, so we wanted to see if feed levels also affect how well algae reduce the formation of seaweed. Methane emissions from livestock with a high nutritional diet decreased by 33% to 52%, depending on how much seaweed they consumed. Emissions of cattle fed with a low nutritional diet decreased by 70% to 80%. This difference may reflect lower levels of an enzyme involved in the production of methane in the intestines of low-fiber, nutritious diets. One important finding was that the bulls in our study converted up to 20% more efficiently into body weight than cattle on a conventional diet. This benefit can lower the cost of production for farmers as they have to buy less feed. For example, we calculate that a producer who finishes 1,000 beef cattle – that is, feeds a high-energy diet to grow and add muscle – can reduce feed costs by US $ 40,320 to $ 87,320, depending on how much seaweed consumes the cattle. Global methane sources include fossil fuel burning and biomass, agriculture (mainly livestock), landfill waste disposal and natural decomposition in wetlands. Jackson et al., 2020, CC BY We do not know for sure why feeding livestock supplements helps them convert more of their diet to weight gain. However, previous research has suggested that some rumen microorganisms may use hydrogen that will no longer produce methane to generate energy-dense nutrients that the cow can then use for extra growth. When a panel of consumers tested meat from cattle included in our study, they found no difference in tenderness, juiciness or flavor between meat from livestock that consumes seaweed and others that do not. [Deep knowledge, daily. Sign up for The Conversation’s newsletter.] Commercializing seaweed as a feed additive will involve many steps. First, scientists must develop aquaculture techniques to produce seaweed on a large scale, whether in the ocean or in land tanks. And the U.S. Food and Drug Administration will have to approve the use of seaweed as a feed supplement for commercial cattle. Farmers and farmers can also earn money to reduce their livestock’s emissions. Climate scientists need to provide guidance on quantifying, monitoring and verifying the reduction of methane emissions from cattle. Such rules could enable livestock farmers to earn credits from carbon purification programs around the world. This article was published from The Conversation, a non-profit news site dedicated to the exchange of ideas from academic experts. It was written by: Ermias Kebreab, University of California, Davis and Breanna Roque, University of California, Davis. Read more: Heat is a Serious Threat to Dairy Cows – We Find Innovative Ways to Keep Them Cool Young farmers in California are finding new ways to raise livestock and improve the land. Ermias Kebreab receives funding from the Foundation for Agricultural Research, Elm Innovations, the David and Lucile Packard Foundation and the Grantham Foundation. He advises feed additive companies such as Blue Ocean Barns and Mootral. Breanna Roque does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has not disclosed any applicable commitments outside of their academic appointment.