hello and welcome to Technically Speaking where scientists and engineers come together to chat about a common interest share knowledge and satisfy some curiosity i'm Jasmin and I'm joined by Laura to revisit our recent episode on methane made by cows and take a closer look at the biology. Laura what
about the episode intrigued you? So when I was listening to you guys talking after you recorded the episode you were talking about how the methane is made by organisms in the cow's gut so bearing this in mind and the things you were talking about there were two things that interested me how do you select a cow to produce less methane if you're just breeding them and doing selective breeding and then how do you feed a cow or its gut bacteria to do the same thing
so that's the two things you're talking about altering the food or selective breeding them so I did a little bit of digging based on the things that you said and found out some really wild stuff okay cool so those two things then let's take a look at the bacteria first cuz from a chemical engineering perspective cuz we're both chemical engineers by background kind of kind of yeah i would say me more so than you you just have a PhD in chem i have a bachelor's and a PhD in chem so from a
chem perspective bacteria is really important for anorobic digesttors so yeah let's just start there i guess to think of your anorobic digesttor in the cow turn the cow into a chemical engineering system is where we're going with this yes you talking about cows being ruminant so they have different compartments of their stomachs or some people say four stomachs they each do different things so the first part of the stomach is where they do the ruminant work where the cow regurgitates
its food chews it up in its mouth sends it back down to the ruminant chamber and keeps doing this is where the bacteria break down the food to produce smaller particles and then things like methane as well so in the cow's stomach uh there is a series of different reactions that occur uh you got bacteria that first break down the carbohydrates proteins and lipids into simple actual useful things like glucose fatty acids amino acids but then you've got three more
reactions that end up in the methane being produced so the second reaction is basically you have more bacteria which then are different and also different bacteria which converts the volatile fatty acids and alcohols into other chemicals these then get broken down further by more bacteria to produce acetic acid carbon dioxide and hydrogen and it's the carbon dioxide and hydrogen that particularly important because then you have something that's called methanogenesis where you've got
methanogenic bacteria that will basically produce the methane using the hydrogen and other chemicals being produced so that's basically how you get methane in a cow's stomach yeah so this is what I was reading about there are all these really complicated interactions going on like it's not just one bacterium doing a thing they're all sort of sharing resources and kind of sending things back and forth yeah but yeah ultimately you're right it's about the hydrogen production and how it's
used so there are many metabolic pathways involved in producing or using the hydrogen is what I was reading so obviously methane is not actually useful product for the cow unless cows can somehow develop the ability to burn it in their stomachs to make fuel and energy uh obviously from a chem perspective anorobic digestion you want to get the methane because then you can use that as a substitute for natural gas so from a chem perspective anoroba digestion you're really interested in
the bacteria and how to optimize and enhance the bacteria as well as the conditions of the anoroba digestion so you can get the methane so you can use it as a fuel so I guess in this case it's similar that you want to optimize what the bacteria or the gut fauna or the microorganisms different words for similar thing you want to optimize what they're doing in the cow but for a different purpose you don't want to make methane necessarily you want them to make things that they can use as actual
energy i guess the principles of controlling the populations of the gut fauna are the same so you guys mentioned feeding them an additive um from Bovar if I'm pronouncing that right it's a strange name probably boar bovar who knows well I work in communications as well so you'd think I'd know but we both failed yeah but they use a chemical that's very similar to an enzyme that's involved in combining the hydrogen with the carbon dioxide in that methogenesis series of reactions you were talking
about that's like the final step in what produces the methane yeah and from what I've read there are several microorganisms in the cow's stomach that could use the enzyme so giving them this additive that's chemically similar in shape to their enzyme blocks the enzyme itself from doing its job which I thought was pretty neat yeah that's a really interesting thing you can look into but obviously for anorobic digestion purposes you want the methane currently anorobic digestions the main
way you would make biogenic methane from organic matter so like waste sewage sludge you want to keep that bow of air away from your anorobic digesttor if you're a chemical engineer then well it wouldn't be ideal because we want the methane exactly so yeah you're saying that methane is a useful gas if we can capture it in that well controlled system that a chemical engineer would have yeah that's not necessarily the case for a cow no but there's also more to this story for the cow because there
are other gut fauna or microorganisms that can use the hydrogen to produce things like acetate or hydrogen sulfide or ammonium and those things because they all use the hydrogen competing with the methanogenesis am I pronouncing that right methanogenesis am I putting an extra sound in there methanogenesis that's all right so there are other organisms that can use the hydrogen so instead of producing methane these other microbes can kind of be like hydrogen sinks but the stuff
that you've listed isn't really good for a cow cuz they're kind of corrosive oh no i'm guessing they're producing them in relatively small amounts so that the concentration would be low enough that they're not corroding their own stomachs and they'll excrete them eventually so they might have like eggy smelling gases coming out of them that's hydrogen sulfide yeah humans do it too i guess they do so I read some research that said simply suppressing methane production might not be great because
the hydrogen could inhibit these beneficial microbial processes that make conversion of food to energy less efficient does that that sounds like a really big mouthful there did that make sense made sense to me so basically what I'm saying is just having hydrogen sitting in the cow's stomach or potentially being used by some other processes isn't necessarily enough unless you can also make the cow microbe system use the food more efficiently yeah so there are those different
metabolic pathways that I mentioned different things that the cow's gut fauna do so one pathway they can make use of is to make propionate which consumes the hydrogen and produces molecules which can be used as an energy source by the cow so like glucose or fatty acids I presume so yeah so I feel like just saying stop producing methane isn't quite correct it's making the cow's microbiome work more efficiently to make the cow make better use of its food but you also want to do in a way
that doesn't actually harm the cows but could also maybe potentially make them more productive happier cuz they're they have more efficient digestive systems so they don't have to be as gassy yeah and maybe don't make too much acetate or hydrogen sulfide cuz that'd be bad for them that bad be really bad they want more glucose and fatty acids and potentially amino acids kind of suggesting that there's a lot more research to do to figure out how to really optimize what's going on in the
cow's stomach and I was reading about some cows that were fed the bovar additive which has got quite a long name shorten to three NOP if you like there's a long name yeah um three nitroypanol I think that is three nopeloo yep so we're feeding them the bobar additive three as well as a chemical called fumemerate uh which I which I assume is pronounced correctly there i could be doing it wrong probably i just read the names i don't actually talk to anyone who uses them so your
guess is as good as mine yeah same i was in all this reading online and I've not spoken to anyone about this so I don't know if I'm doing this correctly um so the cow's own microbiome can produce this fummerate and the experimenters found that when they gave the cow's fumemerase as long as the three kn or the bovar less methane was produced overall oh cool yeah and it shifted the cow's microbiome to use hydrogen to make these volatile fatty acids that you mentioned instead of the
methane so it was much better to do that than just to feed them the three knob on its own that is cool so I guess from like a chemical engineering perspective so like technically chemical engineers we do more of scaling up industrial processes from lab or bench scale to massive industrial scale but like a small subset of chemical engineering is around engineering reactions so I guess this could like fit into like how to enhance a bacterial population within
like a certain biome if you did want to shift a reaction in favor of producing certain favorable products rather than stuff that's unfavorable yeah i'd also read that some researchers are looking at feeding cows probiotics or you know good gut bacteria to shift them away from making methane and using their food more efficiently but it sound like it's really difficult because the bacteria don't tend to survive outside of the cow's stomach where there's oxygen
present so I guess getting it into your lab bench bioreactor might present a challenge if you wanted to do an experiment on it yeah I guess that's also true for humans cuz I think the medical advice is like probiotics prebiotics they don't really work because there's not much proof to show that the bacteria actually survives once it's been digested and makes it through to the actual parts of your guts that have the bacteria i can see how that would make sense if it survives only in
your gut it might not get through your stomach acid i didn't really consider that though when I've looked at the food that I eat it's worth knowing thank you yeah I mean maybe some bacteria survives but who knows yeah I was also reading about something that I thought well this is chemical engineering there are some researchers who are developing sensors to monitor concentrations of things like volatile fatty acids and propionates and other things inside the cow to tell the
farmers how to feed them yeah guess they're trying to get them closer to shifting them towards having a really efficient digestive system and minimal methane production with these sensors built into the cow that it sounds like it's a little pill that they eat and it's like wirelessly transmitting data outside of the cow yeah that is really interesting it's also an interesting analogy so in which case should we be moving more towards the selective breeding so my first thought was when I
heard you talking about this in the previous episode how on earth do you select a cow to have good gut microbes there's so much variability going on there it's not just about the individual itself it's about the entire system host microbe interaction and I came across this great study from uh some Scottish researchers where they were looking at the metagenome of these cows to figure out what their gut microbes are doing basically so they essentially take a sample of the rin contents from the cow
analyze all the genes in there to see what the microorganisms are doing which genes they're expressing and this effectively tells them what they're up to okay but like how does this relate to the selective breeding of cows what about the actual genetic makeup of the cow itself rather than what's just in its rin this is what I thought as well it confused me a little bit because they did specifically talk about genetic traits of the cow but then never looked at the cow's genetics what they were
doing was looking for any hereditable influence of the host on this microbial community that could affect methane production ultimately looking to improve the efficiency of the microbes to convert food into useful things and not methane um but it was really controlled experiment this is what so impressed me about this they were taking some cows doing natural cowy things and then controlling as many variables as possible to come out with this really detailed study of what was going on in
their guts and figuring out which adult cow might have an effect and how as a engineer I do like controlled experiments i like it when everything is accounted for and you have less uncertainty but as a human and as a vegetarian although not an ethical vegetarian I would hope that the animals were treated well in these controlled experiments yeah yeah I mean any researcher working with animals has to go through the ethics process and get approval don't they and these cows
sounded like they were treated so well there like palatial conditions they had all these immunizations they were really disease-free they seem to have all the food they could eat they were grass-fed outside for a while before coming inside for control conditions it sounds like they were treated just amazingly well until the end of the experiment okay so in terms of like controlling these experiments like how do they actually control all of the variables cuz cows do
what they want to do yes so to look at these hereditable factors that may affect what's going on in the cow's stomach they selected some purebred male cows Abodine Angus and some I think they're pronounced limusen cows like limousine but slightly different I guess yeah with no e and then they had a range of females who were artificially inseminated from these male cows and they made sure they weren't using twin offspring so that each animal ended up with its own
specific maternal effect that would influence the microbiota so the maternal effect isn't controlled but the male effect or the paternal effect is controlled and they ended up with 36 cars from each male cow breed so a reasonable sample size of 72 that's a lot of babies yeah a lot of space isn't it for cows to get big and be happy so they took about five weeks to adapt these cows their experimental diets they had two different diets as well they were either one that was predominantly
high forage or natural grassy stuff I guess and one that was predominantly high concentrate or the artificial feed that they might get they were given time to get used to the pens they were living in and the electronic feeders that would measure their food consumption so how much food the cows ate every day was measured and how much weight gain they had was recorded as well so 56 days so quite a long experiment i mean is it not a chemical engine is a longer experiment
you tell me i mean I think 56 days is pretty decent cuz uh it's also sounds quite expensive cuz you've got a lot of cows need a lot of space and that's a fairly decent size for like just taking samples yeah I'm guessing it kept the researchers quite busy yeah I'm assuming what they were most interested in was me saying but also stuff related to the cow's digestive system you can kind of test their poo but you get more information once the cow's dead and you
can investigate their guts they did put the cows in um the gas analysis chambers these guys mentioned in the episodes yeah their word yeah so they measured their methane production um they did also sample some of the room and this this amazes me they basically took samples of the cows in sides while they were alive some while they're alive and then some after they were slaughtered I think but then they did this like massive data analysis of all of this genetic data from the gut bacteria or
the gut organisms to figure out what was having an effect on methane emissions and what was having an effect on converting food into useful products by sort of correlating that with the diet they had or their breed type and kind of ruled out all these different factors and figured out what was making an effect on what so in terms of like what dietary factors are important for cows in specifically around microbiomes and influencing methane production what did
they find they noticed quite quickly I thought this was quite interesting it's a side point to the research but they noticed that Abdian Angus carves tended to have higher methane emissions but then they also noticed those cows ate more food so when they accounted for that it was the same as the Lemusen cows i guess that just suggests those cows grow more quickly they they've done some previous work it sounded like that they were sort of building on in this study
to look at the differences in the bacteria that produce the methane and other bacteria and looked at the ratio of those two species or populations to see if there was a difference between the two different types of adult male cow that had given rise to these calves i feel like I'm talking in a really roundabout way here and I don't know why so they found previously that they can use this ratio of methanogenic bacteria to other bacteria to predict methane emissions that seems to correlate
reasonably well with the type of animal it's come from okay cuz they proved to know that is that something that they used to choose the cows because they only used Angus and the not limousine but limousine minus an e type of cow i assume they did although they didn't seem to outright say that in the research but they were definitely looking at cows that produce a lot of methane versus cows that didn't produce a lot of methane within the different populations they were looking at and
looking at differences there was there something useful from the experiments that scientists now can use or do we need to do more research i got the impression that they need to do more research because they found this trend in predicting what a cow produces based on that ratio of different gut populations yeah and the one of the questions they were trying to answer in the research was obviously what can be inherited from one adult to the offspring so effectively how does the
host genetics control the microbiome and they didn't exactly answer that question they did say there's not a lot of evidence out there for hereditable traits that relate to this but they did do a little bit of a literature review and said that things like pH of the rumin which is controlled by their saliva can affect things like short- chain fatty acid absorption and how long it takes for certain products to pass out of the rin which can affect efficiency and they also said that the
variation in physical structure and size of the rin as well as the intensity of contractions and passage rate of digestates uh all could have an influence on rin microbial community and how many of each kind of microbe there are and all of those traits they say are hereditable so I would imagine they then start trying to look at the genes that affect those different traits of the cow and see what's going on there but I don't know maybe I'm thinking about this
in too much detail and they need to take more of an engineering approach and just look at the cow how does the saliva affect the pH of the rin does that also happen in other animals or is it just animals with a rumin they didn't specifically say they mentioned that the saliva contains bicarbonates okay and that was mainly it and it controls the pH between about six and seven whether that's the same in humans not a clue or sheep that have rumin or other animals that don't have rumin I
don't know something to look into for future episode maybe yeah could we could just do an episode on how to have healthier guts i guess we could apparently it's not eating probiotics though no I think that's a good place to leave it i think we're kind of going off topic now i agree uh unsurprisingly uh looking at what happens inside a cow's digestive system is amazingly complicated and it sounds like more work is going on in terms of how to optimize cow feed while also selectively breeding
cows the sort of detailed work is really needed to help reduce methane emissions to help address the climate emergency yep sounds like a fair summary of what we're saying in this episode and the original one you guys did yeah uh thanks for listening and we'll see you next