Reducing methane production from pastoral agriculture lies at the heart of efforts to make pastoral agriculture more climate friendly. If only sheep and cattle could be made to stop producing methane!
Here I look at the challenges of making this happen. Unfortunately, those challenges are not easily solved. It is a lot harder than the uninitiated might think.
This is not just an issue for farmers. It is also an issue for all New Zealanders, given that almost half our exports come from pastoral agriculture – currently more than $32 billion per annum. According to MPI, approximately 82% of all exports come from primary industries once timber, fish, horticulture and wine are included.
Without primary industries in general, but particularly pastoral agriculture, we are in very big trouble as to how to pay for all the imports of goods that we cannot produce here in Aotearoa New Zealand. Solving the methane issue would be a real big deal.
The starting point to understanding something about methane is to appreciate why ruminants produce methane. The quick answer is that it is a fundamental component of how ruminant animals, with their distinctive four-stomach system, have been designed by nature to digest grasses.
For humans, pigs, chickens and other species with single stomachs, known in biology as ‘monogastrics’, it is not possible to digest grass efficiently. Accordingly, if humans try and eat a meal of grass, they will get a sore stomach and very little sustenance. Indeed, it is simply not possible for humans to survive on a grass diet.
In contrast, ruminant animals such as sheep, cattle, goats and deer have a four-stomach system, designed by nature through evolutionary processes so as to be able to digest grasses and other high-fibre forage crops that contain cellulose. The ruminants do this with the help of trillions of bacteria that live within the rumen system. These bacteria ferment the cellulose in the grass to form volatile fatty acids which can pass though into the bloodstream of the ruminant.
This process of ruminant nutrition leads to carbon dioxide and hydrogen as waste products. At this stage another group of micro-organisms called ‘methanogens’ come into the picture. They turn the waste products into methane, with four hydrogen atoms attached to each carbon atom. The ruminant then burps up the colourless odourless methane.
When nature first designed ruminants through evolutionary processes, there was no need to minimise greenhouse gases. These gases only became an issue once humans interfered with natural processes by digging up huge quantities of fossil fuels that had been buried for millions of years.
Modern science tells us that it is water vapour first and then carbon dioxide that are the main greenhouse gases. But methane also happens to be a greenhouse gas that absorbs infrared rays at specific wavelengths as they travel back from earth into space. So methane, which ruminants have been happily burping for millions of years without a problem, are now considered to be part of the modern greenhouse gas issue.
The problem is that nature’s ruminant nutritional system was designed for a purpose over millions of years by trial and error. That is how evolution works. And nature does not necessarily take kindly when humans want to interfere with the basics of that ruminant system. Change part of the system and there is always a good chance that the overall system will fall apart.
One way or another, the excess hydrogen has to be removed from the rumen. Otherwise, the rumen will turn from a fermentation vat to an acid vat. The animal will not be impressed and will get very sick.
Accordingly, it is not just a case of killing the methanogens. Something else has to take over the job that the methanogens do naturally. If there was an easy solution that was energetically better than producing methane, then nature would in all likelihood have figured that out itself.
So, what are the technologies that humans have been exploring?
One of the most fascinating technologies is to feed some bromoform-releasing seaweed to ruminants. These trials have been going on both in New Zealand and overseas. The bromoforms are particularly good at killing off the methanogens, but unfortunately, they tend to also mess up other parts of the rumen system. Particularly important is the finding in a recent scientific paper that bromoforms pass from the rumen into milk.
Alas, bromoforms are a suspected carcinogen and certainly have the ability to interfere with many human processes. My own assessment is that, despite some ongoing hype, there is close to zero chance of this technology being acceptable to food-safety authorities. Indeed bromoforms, which are similar in their action to chloroform, are already widely banned in foodstuffs.
The second feed additive that has generated considerable hype is a chemical called 3-NOP. This has been developed through to early-stage commerciality by Dutch firm DSM with the trade name Bovaer.
This technology appears to be much safer than bromoforms and does reduce methane production in feedlot situations for dairy and beef cattle. However, the evidence to date is that it does not work under pastoral conditions because it needs to be evenly distributed throughout the feed.
Fonterra has been working with DSM to try and develop the technology for pastoral situations. The barriers are formidable. Whispers on the breeze are that Fonterra’s research has not gone well and that there are some very glum faces. At the very least it is a long way from commercialisation for pastoral conditions. Also, there are good scientific reasons as to why it is highly unlikely to ever work anywhere near as well in pastoral situations as it might do in a feedlot.
The other area of hype which has been around for the best part of two decades is a vaccine that leads to methanogen destruction. Research has shown that it is possible to get the animals to produce antibodies that travel via the saliva to the rumen, but getting the antibodies to actually work in the rumen is another matter. This technology has remained somewhere out beyond the ten-year horizon for more than a decade and commercialisation has not been getting any closer. Once again there are some glum faces.
Another technology has been genetic selection for low-methane-emitting sheep and cattle. This is definitely feasible and may be a modest success. In sheep, where the research is most advanced, the lower-emitting animals have smaller rumens and produce more propionic acid than what occurs in the higher-emitting animals. Also, it seems these characteristics are inheritable.
However, there will be limitations to how far that technology can be taken. There are good reasons why fatty acids other than propionic acid, and which produce more methane, also have to be produced. It could be a useful tool in the toolbox but once again there is some risk that it is being overhyped. Caution is appropriate until there is more evidence as to how these animals perform under rugged pastoral conditions.
Pulling all of this evidence together, the big picture is that there are no magic technology bullets that can drastically alter the reality that ruminants emit methane for a good reason. This methane is the outcome of evolutionary processes that produce animals that are fit for the grassland environment in which they live naturally.
However, that does not mean that no progress can be made in terms of emitting less methane per unit of meat and milk output. Indeed, the last 30 years have produced an amazing but seldom told New Zealand story as to how methane emissions per kg of sheep meat have reduced by about 30%. Dairy emissions per kg of Milksolids (fat plus protein) have reduced by about 20%.
The way these spectacular efficiency improvements have been achieved is by the breeding of more productive animals and incorporating these animals within improved farming systems. Fortunately, improved biological efficiency has also led to efficiency improvements relating to methane emissions.
In the coming years there will be further improvements to be gained in relation to reduced emissions per unit of output, but it will be hard work. Each percent of gain is more challenging than the previous one.
One particularly promising field of endeavour is the methane produced in effluent ponds rather than inside the rumen. But across the all-species ruminant system, methane from effluent ponds comprises only about 4% of the total methane emissions.
None of these advances will change the bottom line that there will be no magic methane bullets. As long as ruminants live on the grasslands, they will continue to do what nature designed them to do, and that includes emitting lots of methane.
Given that reality, together with the fundamental importance of pastoral agriculture to the export-led economy, there is lots to ponder.
*Keith Woodford was Professor of Farm Management and Agribusiness at Lincoln University for 15 years through to 2015. He is now Principal Consultant at AgriFood Systems Ltd. You can contact him directly here.
95 Comments
Techno-optimism teaches us all that we can carry on with our current way of life without having to change anything, because technology will solve all our problems for us. As you point out in the article Keith, we've heard all about feeding cows seaweed and genetically engineering their gut bacteria to release less methane, all so we can keep eating steak guilt-free - until we finally master the silver bullet of lab-grown meat, of course. Needless to say that these are all pipe dreams, and the only solution is a change of diet.
Same principle applies to genetically engineering possums and rats to save our ecosystem (remember that?), the hydrogen economy, and - dare I say it - electric vehicles. Promises like these are all too tempting to believe, but the only real solution to a lot of our issues is major - and probably very uncomfortable - changes to the way we live our lives.
How many politicians do you think are going to suggest that?
Actually the answer to the problem, is degrowth. Eliminate the human foot on the throat of the biosphere. There is nothing inherently wrong with eating a steak. It's the number of humans eating steak too often that is the problem. KW correctly identifies the need for agricultural production to pay for our import heavy lifestyles. Perhaps rather than continually doubling down on techno utopian nonsense, we could look at whether we need to import piles of consumer junk, that have a lifetime measured in hours?
Do I understand correctly you are volunteering to adopt a lifestyle more akin to the average Congolese?
The problem is who defines how much steak is too often? The only way to regulate consumption in a fair manner without everyone crying "nanny state" is via price. The current incumbents are having an early and not very ambitious stab at that and yet farmers are crying murder!
But I agree with you, there's no magical tech solution to fix this problem, which is most easily fixed by behavioural change.
Switching from a daily carnivore diet to 1-2 carnivore servings per week (or stretch those 2 servings in daily servings that are flavoured with meat) would actually be pretty easy for most of us. Protein can be easily sourced from many plants (btw hemp seeds are one of the only sources that contain significant amounts of ALL amino acids we need!).
No technological breakthrough required and an instant saving of more than 80% of meat related GHG emissions.
The same can be done with dairy. No one needs to drink milk everyday or at all!!
Plenty of vegan milk alternatives to chose from and the ppl complaining about paying to much for something that is 90% water can switch to drinking water, their wallets will thank them.
We grow animals, we kill animals and we grow more animals that replace the ones we killed. The beef and dairy numbers have stayed very static these last twenty years, at least
Ruminant animals have been present on the planet since before Adam. The methane they produce disappears every 12 years
Let's face it, we are making the animals take the blame for the CO2 that humans have produced
Plenty of people in middle income and developed countries could do with reducing their meat intake, but there's another couple of billion with sub-optimal nutrition who would benefit from eating a lot more. It would be very difficult to replace the protein, iron and nutrients that ruminants currently produce from grass and crop residues.
It's not that hard, especially if you're only talking about reducing your meat intake rather than eliminating it completely.
The tricky one is vitamin B12, which you can't get from plants. But you can get it from fermented foods (courtesy of the same bacteria which produces it in animals' guts), which frankly people should be eating a lot more of anyway.
Speaking from industry experience - there is just so much 'dumb money' chasing sweet-sounding but ultimately illogical ideas that creates these hugely wasteful programs. When spending time with a key global and Oceania seaweed influencer it became clear as he spoke that the pursuit of investors money to save the world and make huge returns on such an investment came at the expense of any reality check as to the feasibility of feeding cows seaweed, and its impact on the animal or human food chain.
Bromoform could actually be synthesized if we really needed it, rather than taking it from seaweed. But in the 1970s it was already shown to be toxic to animals.
And why stop our incredibly efficient form of farming vs other countries globally? We should be increasing the amount of protein we produce (whilst protecting the environment) so that grossly inefficient countries can produce less.
Ultimately our government is led by city folk who want a quick fix and a sweet sounding solution. As such the world and NZ goes backwards on its inability to understand the implications of producing food and feeding people.
We are peeing in the wind on climate change. The actions proposed for NZ will only hurt our economy and give away our market share to higher emitting countries. We should focus on restoring native biodiversity as this will directly benefit NZ wildlife, waterways and well-being. Europe is re-wilding and restoring native forests, we are planting pine trees!
Europe is wealthy enough to virtue signal by importing environmental destruction from developing countries. "Member States will have to rely on importing wood products from elsewhere, at the risk of damaging ecosystems in other parts of the world, while actually increasing the EU’s own carbon footprint."
The pines on my place planted by the previous owners in the 1990s are all falling over. The others in the area have been logged. Not much understory left after logging. Just bare soil, weeds and wilding pines. My 100 year + Taraire block is still going strong, and will be there in another 100 years.
it is certainly unusual for pine forests to collapse at that age, although natural thinning will inevitably occur as the individual pines compete for light and the bigger trees then grow bigger. If wanting to get a transit to indigenous species, than some planned thinning is appropriate, starting at about 10 years. Provisional of indigenous seed may also be necessary to get the transition started.
KeithW
Thanks Kieth.
I am taking the fallen trees for fire wood and letting the understory come through. Quite a few pittosporum and five finger so far. It will never be commercially logged, so it will transition into native. The logged blocks on our neighbouring properties look terrible. The ones upstream of us are now stands of tobacco weed and the silt washes through our wetland after heavy rain. I hope James Shaw is aware of what he is doing to the ecology of our country as he makes a meaningless contribution to reducing global CO2 emissions.
NZ was one of the last countries in the world to be populated. Maori and Pakeha have destroyed a pristine ecosystem in under 800 years. Shouldn’t NZ biodiversity have a right to exist for its own sake? I think James Shaw’s promotion of the pine carbon sink model is damaging to the unique biodiversity of NZ. Just wait for 30-40 years to see the bare hillsides and rivers choked with silt as the pines are cleared. It would be so much better to re-wild with Natives but that wouldn’t hit our short term C02 promises. We are thinking about 2050 when we could be planning for 4050. Tane Mahuta was a seedling when Jesus was born!
Yes , Shaw is very mindful of putting in place policy that a future national government would undo . i don't think he is too bothered what the majority of voters thinks , that's Labour's problem. i do think they need to put alot more effort into explaining the policies , and the reason why they are going that way .
i hope they do go after fossil fuels more, but they need to explain and promote these policies a lot better before the next election.
I agree with you about the pines falling over Waikatohome, maybe it's a Waikato thing. I've got a 30 year old block where the trees are going down like ninepins. As opposed to Kauri and Rewarewa planted about the same time, sure they're a wee bit smaller (although the Kauri are close) but they're young healthy trees with centuries in front of them.
"Fighting climate change is to ensure that the standard of living 20+ years from now is better than it is currently predicted to be."
You are fighting the wrong war Lanth. Lay off the Stuff website.
"Scenarios set out under the UN Climate Panel (IPCC) show human welfare will likely increase to 450% of today's welfare over the 21st century. Climate damages will reduce this welfare increase to 434%."
https://www.sciencedirect.com/science/article/pii/S0040162520304157
solardb,
That is a very interesting question!
Methanogens are part of the silage making process.
So I expect that the methane is produced in the silage itself with less released in the rumen, leading to a similar overall situation.
But, I also think using first principles that it might be much more possible to alter the methane process within the silage than in the rumen.
And I think I might have figured out how it could be done. So that thought has now got me very intrigued and also a little excited. I will now need to discuss that with some other people to see whether my thinking stacks up.
KeithW
So methane, which ruminants have been happily burping for millions of years without a problem, are now considered to be part of the modern greenhouse gas issue.
The problem is that nature’s ruminant nutritional system was designed for a purpose over millions of years by trial and error. That is how evolution works.
So Ms Adern and Mr Robertson, lets levy farmers on something that evolved over millions of years and wasn't a problem until you took power. Something sure does stink about that...
We should not have signed the global methane pledge (although with the history of countries keeping their promises in these things, perhaps it doesn't matter).
It's all very well for countries who have fossil methane leaks they can fix - that costs little and doesn't affect food production.
If we do follow through before new technologies become available it will just lead to emissions leakage.
As the atmospheric concentrations of greenhouse gases continues ever upwards - methane levels in particular........https://www.theguardian.com/environment/2022/oct/26/atmospheric-levels-…
NASA satellites circling the globe measuring methane plumes are finding that leakage from coal mines and oil and gas fields are dramatically under reported by the industry. They're a bigger source of atmospheric methane than agriculture.
Vegans and fossil fuel companies have managed to form a strong association in people's minds between methane and ruminants, in fact a lot when asked to identify the number one cause of climate change will say cows, but in fact if we eliminated fossil fuels it would fix methane as well as CO2.
There's a lot of old unused small oil wells in the USA particularly, but presumably everywhere with oil extraction historically, that rust and leak gases 24/7. There are some trying to take the industry to task over it in the USA but this is a David vs Goliath situation and David has less money to play with
Thanks Keith. I have been following the seaweed story with interest yet have never had the mechanics explained nor the downsides. Now I know. Disappointing.
Someone needs to invent a device that detects a belch and triggers a small pilot light near the animal's mouth. Methane converted to water and CO2. Solved!
Burp catching face mask for cattle
https://www.wired.co.uk/article/cows-climate-change-methane-stop
Thanks for the in depth article Keith. Taking the personification a little further, I think that when nature first designed ruminants through evolutionary processes, it did not foresee the significant forced growth in ruminant biomass on Earth and therefore did not see the requirement to account for ruminant greenhouse gases. But thanks to Fritz fertilizer as well as a fenced paddock with a bull and many cows, there is now more 'ruminants' than ever before. Alongside the multi billion 'monogastrics' out there, Earth also has multi billion sheep and cattle.
The problem as chebbo aludes to is probably very uncomfortable, and even confronting. Let's face it we're all just beating around the bush talking about reducing methane in ruminants.
Correct, because of the Haber Bosch process and other farming technologies from the early 1900's we have far more ruminants and monogastrics on Earth at any one time than ever before. As a result the bio diversity of the planet is in tatters. While we all love eating meat and long may it continue, my comment, really implies that we should stop looking to squeeze the last kg of efficiency gains out of farming, or stop looking to reduce the natural process of methane emissions from ruminants and just confront the truth. Stop beating around the bush. An ever increasing number of people on Earth wanting to live a 'modern western' lifestyle, leading to excess pollution via carbon, methane, consumption as well as leading to excess inflation as more 'money' chases the same amount of consumables (or less in some cases) driving the price of said consumables up.
You can either reduce the amount of people or reduce the desired western lifestyle. Both are unpleasant conversations. Ultimately, something has to reduce and that is what is occurring now, globally, albeit over the course of years / decades as opposed to days / months. Ka kite anō au i a koe.
Thanks Keith. Sobering comments that highlight, for me, the scary disconnect between ideology and consequences. My perspective on the impacts of 20% reduction in ruminant livestock will have major economic consequences in the pockets of all NZ's citizens for the simple reason that export earnings will be reduced significantly.
Is each individual living in NZ willing to take a cut in living standards to enable NZ to live within it's means?
Has the 70s experiment in response to the UK joining the EEC - i.e. to farm more ruminants to produce meat with sheep numbers topping 70 million - been compared for methane emissions against current livestock numbers? That was a government, not farmer driven policy, with significant environmental downside, particularly on north Island east coast hard hill country.
Then the great unwind in the 80s and 90s. My simple search identifies that in 1981 NZ farmed 77.3 million head of livestock (sheep 70m, beefcattle4.5m, dairy cattle 2.8m) which on a standardised stock unit (su) basis amounts to 101.82 million su (1 sheep = 0.89su, 1 beef cattle = 4.8su, 1 dairy cattle = 6.4su). In 2021 NZ farmed 36.1m head of livestock (sheep 26m, beef cattle 3.9m, dairy cattle 6.2m) equating to 81.5m su. Even discounting genetic gains for lower methane emissions per animal, I expect that ruminant emissions over that 40 tear period ruminant methane emissions will have reduced 20%.
The cynic in me leans to lobbies cherry picking analysis time frames to suit their ideological objectives.
We only have a problem with methane emissions because they are calculated with an inappropriate method ,
GWP instead of GWP* and referenced against our human population. The result of this calculation is that greenhouse gas emissions from pastoral agriculture in NZ are deemed to be about 48% of NZ's total emissions when referenced on a per capita basis. This is considered to be high by world standards. But human population is a fluid construct in a constant state of variation. A much more solid base for comparisons would be to (properly) calculate methane emissions and reference them against the land mass of individual countries. If NZ's emissions were expressed per square kilometre rather than per capita maybe the result would compare more favourably with other countries and we would remove the justification for self flagellation we are presently enduring.
wee willie winky,
Although there can be debate about the best metric, there is no doubt that each methane molecule released into the atmosphere does cause some level of warming compared to if it were not released. Hence, we are not going to win any arguments based on a simple premise that methane can be ignored.
KeithW
And even so we are quite content to ignore all other biogenic sources of methane. Simply put the digestion/decomposition/nutrient recycling phase of the carbon cycle has a methane component in every living ecology. Wetlands being the greatest producers. The methanogenic archea are not just confined to rumens but are free living. When aerobic bugs run out of air the anaerobes take over and methane results. This is why the Amazon is the largest point source of biogenic methane on the planet (water logged soils and massive biomass turnover=a great natural phenonemon). I rather suspect that if we bothered to measure it we would find that our West Coast forests will exceed our ruminant production of methane. The over-riding point is that biogenic methane sources and sinks are in balance and cyclic. Fossil fuel releases are additive.
This is actually a critically important point; perhaps we should compare methane produced against the natural baseline. Wetlands produce methane. Most of Southland's dairying occurs on drained wetland. What is the net change in methane produced against the natural baseline?
KW I quite agree- it is the quantum of emissions that should be concerning us. But if we were to express those emissions in absolute terms, eg x gigatonnes versus those of say France at 4x gigatonnes we would have less justification for the present level of hysteria which runs something along the lines of " at 48% (being) the highest in the world". At present we are placing our whole economy at risk based on a misguided perception.
Hi Keith, appreciate your commentaries and the common sense they offer which is otherwise in short supply.
As a casual observer it appears to me that the government's recently announced scheme is flawed in that it taxes emissions but doesn't account for (or credit) the CO2 that is taken up by plants at the start of the process.
Interested in your thoughts on this
Thanks
Tim
"To find the carbon dioxide emissions that would actually have a similar impact on global temperature as methane emissions, you need to multiply those methane emissions by seven (not 28)"
https://www.newsroom.co.nz/ideasroom/a-climate-neutral-nz-yes-its-possi…
How about a positive story with cattle? Water cycles are a far more significant factor affecting climate than methane. Healthy cycles moderate whilst broken water cycles exacerbate global heat dynamics. The link below shows reversal of desertification and healing of water cycle in the Chihuahuan desert through managed ruminant grazing.
Presumably the advantage is that you can still grow the grass here, adjacent to the cows. You just control where they digest it. Even if it were to just encourage them to lie down there while digesting. Capturing the escaping methane is the goal here. I'm just curious to hear about the feasibility, if any.
I wouldn't be so quick to dismiss Asparagopsis Keith. It has been shown to give very high reductions in methane output with no associated reductions in feed intake. Also, cherry-picking one study that found bromoform in milk to base your decision is unwise, especially as lower levels of bromoform was found in the control group as well. There was another study that found bromoform in milk but then they tested the water and found levels in that too. We need more studies before dismissing Asp. entirely
Hi Keith,thanks for another enlighting article backed by science rather than emotions.To your knowledge has there been any scientific studies done on using ionophores such as monensin sodium to reduce methane in ruminants when added to feed or water system.I have been using rumensin in both systems for my dairy cows & even though quite expensive (3cents per cow per day in meal,9cents per cow through water system),for 20 years now & there are multiple benefits including bloat control which helps with ease of fermentation inside rumen.Regards
Dairy farmer joe
I am not well informed re monensin but I have done a quick search in response to your question and it seems that the methane benefits are very modest, on average about 3%, and inconsistent. Those benefits seem to relate to increasing the level of propionic acid production in the rumen. Propionic acid produces less hydrogen compared to other fatty acids for the methanogens to feed on. The inconsistent results probably relate to it working better on a high quality diet as propionic acid production is easier to achieve on high quality diets. Most of this work has been done on feedlot-type animals (dairy and beef) and in those situations 3-NOP seems to work better.
KeithW
Good fact session Keith.
Its a very hard issue - we are decreasing our intensity very well - and need more of that but the thorny problem is total volume emitted and as Simon Uptons paper showed the effect of this not only now but from the past and essentially how this is allocated around the world - international grandparenting problems.
No easy answers and some difficult decisions coming/here. I just hope we can work out a solution within NZinc and it dosn't end up being imposed upon us by overseas forces via the market etc in time. As small player this could be even more painful and full of nasty unknowns out of our control.
Based upon the current uproar I do worry about our ability to work through this ourselves for the least harmful effect.
Exactly, well put
So remove/reduce/increase the input cost of the fossil fuel and surprise surprise the methane problem shrinks. So simple. But of course the rest of the population will feel that as well therefore it's so much easier to collect the low hanging fruit of bio methane and offset the rest so it can be business as usual for most.
No one's blaming the 1 cow that burped, but more that we (the proverbial we) have too many cows burping too much. Why do we have too many cows? Because people are chasing profit and money, people are using fertiliser and relatively modern technologies, and there are just too many people wanting to live wealthier lifestyles, compared to past generations. Don't get me wrong, this isn't just about cows, this is about almost everything that we the people consume. Something has to give. Governments and various lobby groups are in a never ending fight to ensure that their industry survives with as few casualties as possible.
Meanwhile, down in Southland 800 farmers turn up at ILT Stadium and another 300 watch online an event organised by Fed Farmers. https://www.stuff.co.nz/national/130286957/fed-farmers-call-for-alterna…
https://www.stuff.co.nz/national/130295702/minister-unimpressed-by-fed-…
And the world methane emissions rises. Not one mention of cows or even livestock,so famrers can not feel picked on , at least not by world Met service.
https://www.stuff.co.nz/environment/climate-news/300721843/climatewarmi…
Your work is always excellent Keith!
The science is fascinating & open forums such as this are excellent for a lay person to understand the wider challenge!
Almost as a complete diversion I co-share a working space with a communications manager for the Spanish Poultry Industry. The huge complexity of changing regulation, bio-contamination risks, environmental & PR challenges for these European farmers in some respects mimics NZ's issues. It appears farmers are becoming increasingly nervous about media attention.
Please keep up the educational articles.
The UN has just declared that we have missed our opportunity to keep global warming to no more than 1.5 degrees.
Congratulations, human race you have argued the toss all the way to that, and I fully expect the arguing will continue on till we can no longer survive on this planet.
On yer, deniers.
"When nature first designed ruminants through evolutionary processes, there was no need to minimise greenhouse gases." When ruminants evolved 50 million years ago atmospheric CO2 was 1000ppm. Why would cows be worrying about a measly 400 ppm? If fact cows are probably hosed - as well demonstrated by the greenhouse grown crops - growth doesn't really start cranking growth wise until 1000ppm.
One key additional bit of information about the lower methane lines of sheep is that while the rumen is smaller (not necessarily 'small', though) the surface area is the same, as the papillae in those rumens are denser.
Leave aside the issue of GHG, the intriguing thing about these lines is methane production is an energy loss. So just small reductions can be significant for animal 'efficiency'. That might be why the trait has positive genetic correlations with key productivity traits. Also bodes well for harder country, from the feedback I've seen from breeders working with the trait
Key thing will be how it gets integrated & balanced in selection indices with other traits. And on that - "it seems these characteristics are inheritable." - think that is proven beyond doubt now, and its a surprisingly high heritability for such a complex trait, h2 ~0.2 I think?
Aaron,
We are in broad agreement that there are prospects for low-emission sheep. My concern is that the prospects do not get over-hyped. And I am starting to see evidence for that within some sectors of the industry.
The increased papillae should or could increase rate of VFA absorption once they are formed, but I doubt whether it will increase the fermentation rate.
I don't think low methane emissions will necessarily reduce energy efficiency because the energy is embedded in the H2 which has to be emitted somehow. Do you have data as to changes in the ratio of propionate relative to other VFAs? - that is always going to be the likely answer as to the driver of lower emission intensity in these low emission sheep because propionic acid releases less hydrogen. I would expect that getting benefits from changing that ratio will vary depending on pasture quality.
I think it will take quite some time before we know whether there is an opportunity cost associated with selecting for low emission traits. It would only take a very small reduction in animal productivity for the overall emission intensity to increase rather than decrease.
KeithW
Hadn't checked back on this ... Quite agree with avoiding over-hyping - and the other side of that coin is scaremongering. Both to be avoided. That's where its interesting to listen to the likes of John McEwan who knows a bit about sheep genetic improvement, he seems fairly positive on balance. As he points out, this is relatively long term work now. And EBVs are in essence the results of long-term trials, that's what goes into calculating them - especially with across-flock analyses. The low methane line have a high index compared with the high line, interestingly enough.
There were a couple of papers on VFA ratios at recent NZGA/NZSAP conference, will be online now. Interestingly sampling rumen fluid and using VFA profiles could be a simpler (albeit less accurate) method to assess methane efficiency. Will be especially useful for deer, there was another paper at conference on the challenges of measuring for them - understandably a bit more tricky.
Time will tell. Maybe there will be hidden negatives, the pleasing thing is they haven't shown up so far on balance
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