> large mammal farts going on now is probably not that much higher than it always has been
I believe a big part of it has to do with the feedlot diet— when they're eating a high-calorie diet of mostly corn/grain instead of their natural diet of grass, it puts their digestive system into overdrive.
EDIT: I looked into it a bit more after posting this, and it looks like it's not clear-cut— for example, it takes a cow a lot longer to reach slaughter weight eating grass, so even if they're belching less during that time, it's a long enough time that it may be a wash, or even worse: https://www.nytimes.com/2020/10/21/climate/beef-cattle-metha...
The corn consumed by cattle includes the corn stalks which are more or less the same as consuming grass. Corn is after all in the grass family. The actual kernels of corn increase the calories versus grass, but it’s not like cows are just eating corn off the cob all day long. They need to consume tons of roughage to help with their digestion. I think a good argument is that converting grain and grass to beef is inefficient - if you could have consumed the grain yourself, but the nice thing about cows is that they convert very low calorie foods into high calorie meat that we can consume. If we had to eat what cows do, we’d be chewing all day.
It is well documented that once cows are switched to the pure corn diets we now feed them, their health starts immediately declining and they start dying. Factory farms time it so that they grow up on grass and similar, then are switched to grain to fatten them, and are slaughtered before becoming too ill. There are many unhealthy modifications made to their diet and environment to force them to consume corn. This is detailed lots of places including the book The Omnivores Dilemma. The whole book is essentially about corn and what a horror show industrial agriculture/meat is.
Yes. Large parts of North and Central India eat wheat a lot, as chapati, roti, paratha, naan, bhatoora, poori, daliya (broken wheat), rava (semolina), etc. Even in South India a good amount of wheat is eaten as rava (rava upma and rava dosai), chapati, poori, parotta, etc.
Same for monocrop fields of Soy beans, doused in pesticides & chemical fertiliser.
There is a better way all around, with a mixture of animals and crops. And you very much need the animal dung to fertilise if we're talking about doing anything postive for the environment.
They don't get silage unless the farmer makes a point of it. Most of the time the stalks and chaff and spit out the back of the combine and tilled under. Furthermore they'd get penalized for it in weighing if its mixed in with the corn so there's little to no incentive for the extra work of it. If the farmer has a small enough herd though they may let them roam on the field afterward, but the big lots don't do that.
They are constantly feeding the grass with their poo.
Re-generative agriculture using a variety of animal grazing in rotation is more efficient and better for wildlife and the planet than any monocrop vegetable field will every be.
Organic agriculture only works with large amounts of animal dung.
> for example, it takes a cow a lot longer to reach slaughter weight eating grass, so even if they're belching less during that time, it's a long enough time that it may be a wash, or even worse
For that cow, yes. However, the entire herd will reach slaughter faster on a high calorie diet, there's greater turnover in the herd and more methane gets produced for a smaller number of total cows.
If "for a cow" the lifetime emission is the same (say because the daily emission halves but the cow lives twice as much), then the rate of emission "for the entire herd" will also be the same (everyting else being equal). The herd will contain two "low-emissions" cows for each "high-emissions" cow.
>It takes a cow a lot longer to reach slaughter weight eating grass, so even if they're belching less during that time, it's a long enough time that it may be a wash, or even worse.
This would still mean the cows live shorter lives and fart more intensely in that time. So that would destroy a headcount comparison with previous levels of wildlife, since basically now you're comparing one life of a bison with hundreds of cows living in it's lifespan.
EDIT: it must be part of cow digestion. I just remember that cow burbs are bigger methane problems, but cow farts are fine. Still not sure about methane from grass dying normally, and maybe there’s lots extra grass being grown for cows that wouldn’t grow normally?
Aerobic decomposition, exposed to oxygen like dead grass on the ground, produces mostly CO2 and H2O (plus some other O based stuff like SO4, PO4, NO3). Anaerobic decomposition, like in a cow's stomachs, produces mostly CH4 and CO2 (plus some other H based stuff like NH3, H2S, PH3).
I believe a big part of it has to do with the feedlot diet— when they're eating a high-calorie diet of mostly corn/grain instead of their natural diet of grass, it puts their digestive system into overdrive.
EDIT: I looked into it a bit more after posting this, and it looks like it's not clear-cut— for example, it takes a cow a lot longer to reach slaughter weight eating grass, so even if they're belching less during that time, it's a long enough time that it may be a wash, or even worse: https://www.nytimes.com/2020/10/21/climate/beef-cattle-metha...
EDIT 2: Here's a piece which makes the original case, acknowledging greater direct emissions but claiming a savings that makes up for it from soil sequestration due to grazing: http://newzealmeats.com/blog/grain-fed-vs-grass-fed-beef-gre...