Feed additive solutions to methane problems
Agriculture, as we all aware, is a significant cause of our climate and environmental woes. The statistics confirm that the sector is responsible for 38 per cent of Ireland’s greenhouse gas (GHG) emissions, which are made up of carbon dioxide, nitrous oxide, and the main culprit, methane. Methane accounts for 72 per cent of all agricultural emissions here, produced as a result of enteric fermentation of food or feed in the rumen of cattle and sheep, and also by stored manures and slurries.
It is a big problem for the farming community, but the solutions are coming through. Professor Sinead Waters, principal research scientist, Animal and Bioscience Department, Teagasc addressed the Department of Agriculture, Food and the Marine’s recent conference, Agriculture and Climate Change – Science into Action. There, she gave attendees an update on just some of these solutions. Specifically, she focussed on the role of feed additives in the reduction of enteric methane production in ruminants.
Reducing our emissions
Under the Climate Action and Low Carbon Development Bill, the agri-sector is committed to reducing emissions by 25 per cent by 2030. To get to that, we must reduce methane emissions by 10 per cent, particularly enteric methane from ruminants, said Prof Waters. Before delving into the specific role of feed additives in this, she touched on the other ways that farmers can help reduce emissions. “We can improve management practices, reduce age of slaughter, reduce age of calving, and ensure that all animals on the farm are healthy and productive. We also need to ensure that our grassland is managed properly.
“We have very good opportunities in Ireland, we are a pasture-based production system and we can produce animals very efficiently on pasture, and we know that significantly lower methane is derived from pasture-based settings.”
Research – feed additives
The use of feed additives, said Prof Waters, is one part of a multi-pronged approach, and based on Teagasc’s Marginal Abatement Cost Curve (MACC), they can play an important part. “Feed additives can reduce methane emissions by as much as 788 kt CO2 equivalent by 2030,” said Prof Waters. So, these additives have great potential, but like everything, some are better than others. In developing a feed additive for ruminants, what are the key priorities? Prof Waters explained: “There needs to be consistent methane reduction, we need to be able to count that reduction, and know exactly how much the feed additives will reduce methane by.” Additionally, there needs to be good mechanism of delivery to the animal, preferably in pellet form, so that it is easy for the farmer to get the feed additive into the animal, she said.
“We need to be able to count it in the national inventory and it is critically important that any studies are published, and peer reviewed. There is no point in us doing all this research if it can’t be counted in a mitigation strategy.
Also, there needs to be no food safety or residue implications for consumer acceptability, and no negative performance affects, or palatability issues for the animals.”
She continued: “What would be really desirable is a feed additive that is low cost, and that gives increased performance benefits. It would be ideal if it was natural in origin so we wouldn’t have to go through the regulatory process, and it would be ideal if we could combine it with other strategies.”
Meth-Abate
Prof Waters updated the conference on the 2019 DAFM-funded Meth-Abate project, involving collaborators from University of Galway, Teagasc, Queens University, the Agri-Food and Biosciences Institute (AFBI) and industry partners. She explained: “In this project, we set out to evaluate the mitigation potential of a range of feed additives across Irish production systems including [the product] Bovaer, seaweeds and seaweed extracts, lipids, lipid extracts and novel oxidising methane inhibitors. We also monitored their effects on animal performance.
“We also tried to generate slow-release options at pasture and this work is ongoing. We are also examining the nutritional and toxicological composition of the meat and milk to make sure there are no residues, and we do a lifecycle analysis which is critically important, specifically relating to seaweeds,” she explained.
Using the Rusitec system, which is a rumen simulation technique, Prof Waters explained, the project has been able to put a lot of feed additives to the test. And, using a GreenFeed system, the researchers were able to measure methane in real time. Prof Waters explained how this is possible: “The animal is enticed into the GreenFeed system by a feed bait. It sticks its head under for at least two minutes and methane and carbon dioxide sensors – and more recently we have hydrogen and oxygen sensors as well – measure these visits throughout the day.”
3-NOP
The first feed additive under research was 3-Nitrooxypropanol – also known as 3-NOP, which is the active ingredient in Bovaer. According to research literature, the reduction in methane is around 30 per cent. Its mode of action involves it binding to the methane-producing enzyme, called methyl-coenzyme M reductase (MCR). This results in inhibiting the formation of methane without a negative influence on the animal. The effects of 3-NOP are immediate, explained Prof Waters: “It acts like a switch. When the 3-NOP is fed, the emissions are reduced by 30 per cent in an indoor system with a TMR diet.” However, when 3-NOP feeding stops, the emissions increase again, so this creates challenges to incorporating 3-NOP into a pasture-based diet. The feed additive is European Food Safety Authority (EFSA)-approved for dairy, and it is hoped that it will be beef approved in the coming year.
Prof Waters explained that Meth-Abate conducted one of the first studies in Ireland on Bovaer at Teagasc Grange, in collaboration with DSM, the company that manufactures it. “We looked at the efficacy of 3-NOP in growing beef cattle from around six months of age. We looked at dry matter intake (DMI), daily methane, and daily live weight gain. We got very exciting results.
“There was a clear 30 per cent reduction in methane emissions in these animals on a TMR diet over a 12-week period. We saw no impact on DMI, average daily gain, and feed efficiency. Bovaer was also assessed at Teagasc Moorepark by Dr Laurence Shalloo’s group, in grazing dairy cows. This was carried out only on animals that were coming into the parlour for miking and as they left the parlour, they were given 3-NOP in a ration.
"Then, the methane emissions were measured at GreenFeed systems outside. There was an immediate and dramatic reduction in emissions as they left the parlour and there was still a 30 per cent reduction two hours post-feeding the additive. However, after three hours that had decreased to nearly back up to control levels.
“Across a 24-hour period, administered this way twice a day at 8am and 7pm, the 3-NOP supplementation leads to a 7 per cent reduction in methane. This is while a slow-release bolus technology is being developed,” she explained. Bovaer was then tested during the dry period, and fed through silage: “The 3-NOP was fed through a diet feeder and there was a 22 per cent reduction in methane emissions, with no significant effects on performance.”
Lipids and oils
Fats and oils are capable of reducing methane emissions, and Meth-Abate tested linseed and rapeseed oil at Teagasc Grange. “They found that 4 per cent linseed oil reduced methane emissions in beef bulls by 18 per cent over a 12-week period. But we did see reductions in dry matter intake of about 5 per cent, which was a problem,” said Prof Waters.
“We saw an 8 per cent reduction when we fed 2.5 per cent of rapeseed oil – or rapeseed cake [when oil is extracted] – to Charolais heifers, with no negative effects on performance. However, oils and fats are costly to add to the diet, but rapeseed oil is significantly cheaper than linseed oil.”
Seaweeds
Using the Rusitec system, Metha-Abate looked at Asparagopsus taxiformis, the red seaweed which, according to the literature, can reduce methane emissions by up to 80 per cent in vitro in beef and in sheep. However, there are issues with red seaweed, explained Prof Waters: “It is a tropical species, is not native to Ireland, so it would have to be imported, and there is a lack of consistency [in results] depending on the batch received, and it is very high cost.”
Of greater concern, it has also potential human- and animal-health impacts. “The active ingredient in Asparagopsus taxiformis is bromoform, which is a known human carcinogen, so this would cause real issues for us to use as a feed additive. Also, studies carried out in Wageningen University showed that when fed for a long period of time, it resulted in lesions on the rumen wall [of the animal], so it would even cause animal health issues,” Prof Waters explained.
Native brown seaweeds, which are plentiful around the coast of Ireland, were also studied. “It is indigenous, is inexpensive. The main bioactive is phlorotannin and it is high in protein,” explained Prof Waters. Research literature indicated ‘very inconsistent’ results. “We found that the best of the candidates was the Ascophyllum nodosum, which we fed at a 2 per cent level, which had no effect on sheep, but had a four per cent reduction in cattle, which was quite small.
“We then worked with our colleague, Dr Maria Hayes, in Ashtown, as part of the Seasolutions project. She generated an extract for us that we fed to the animals and we found a nine per cent reduction in sheep methane and a seven per cent reduction in beef which was much better.”
Oxidising methane inhibitors
Oxidising methane inhibitors are proving to be effective methane-reducing substances, explained Prof Waters: “These are peroxide-based compounds, which are routinely used in human food and so, are regarded as being safe. We used calcium peroxide in our trials – this came out as the best from a range of in vitro studies.” This is now known commercially as RumenGlas, made by Galway company, GlasPort Bio. The product targets methane-producing microbes and is composed of safe ingredients which leave no harmful residues following usage, according to the company.
“We did a trial on Rumenglas in Meth-Abate, where we were able to pellet the product into a nut, and we found that there was a reduction in methane emissions by 17 per cent with a low dose, and by 28 per cent in a high dose.” The beauty of this product, according to Prof Waters, is its ease of delivery in pellet form.
Challenges
The feed additive space is certainly delivering some effective solutions, but challenges still remain in relation to our grazing system, and work is ongoing to develop slow-release and bolus technology. Meanwhile EFSA approval is necessary for some commercial products that are coming on stream.