Eh. Most cattle in Sweden is fed with grass or grass-equivalents. I.e. stuff that humans don't want/can't eat.

Now the idiotic argument that is often heard is "well, if we didn't grow grass we could grow something humans want, like.. soybeans". And the answer is no, we couldn't because the land isn't suitable for growing those high-value crops. If it was the case the farmers would be all over it.

https://jordbruksverket.se/om-jordbruksverket/jordbruksverke...

Horrible link, but it shows that close to 45%(?) is used for "vall/grönfoder" and "betesmark" i.e. grass, grass-equivalents and gracing pastures.

> An economist walks by a twenty dollar bill on the sidewalk but decides not to pick it up, because if it were really there someone would have picked it up already

I think many farmers do what has worked for the last X decades; often copying what their forebears do with small adjustments.

You are not a farmer and have a typical ignorant view of what it takes in knowledge and management to farm.

You can't copy/paste in farming to get ahead, or be really likeable but have no actual output or contribution.

that's a joke based on a particular economic theory, by humor the flaws in the theory are indicated, I'm pretty sure every economist walking by 20 bucks on the sidewalk will pick it up.

I don't think farmers have any particular theory that land growing grass cannot grow anything else or their parents would already have done that. So the analogy is really stretched thin.

It could be rewilded, instead of being used by humans directly. Biodiversity badly needs that.

About 15% is slåtter and grazeland. Slåtter might include some grazing, but the vast majority of things growing there won't be eaten. I think it is pretty safe to say that the vast majority of the grass feed land is suitable for human crops since "vall" is most often used in rotational crop systems.

We CAN grow such crops in Sweden, at least in the southern parts. I lived next to a quinoa field with comparatively high yields. And we have been growing white beans for years. Pre pandemic there were trials with soybeans on Öland and in Skåne with promising results.

> Now the idiotic argument that is often heard is "well, if we didn't grow grass we could grow something humans want, like.. soybeans".

Or we could let the wild take over that land.

> Removing crops as a part of animal feed would mean something like reducing our meat consumption by 90%.

You correctly reference that raising vegetable protein is about 10x more efficient than raising animal protein.

Assuming

* it is ~ 20x more efficient to raise single cell protein than it is to raise vegetable protein

* it is too impractical or inefficient to feed single-cell protein to plants

Then it would follow that it would be 2x more efficient to raise single-cell-protein-fed animal protein than it is to raise vegetable protein. This can happen in closed facilities to capture any methane gas.

We observe it is very hard to convince people to switch from carnivore habits to vegetarian habits. Presumably it will be similarily difficult to convince carnivore population to voluntarily switch to eating single cell protein.

It will obviously still be 10x more efficient to eat the single cell protein directly than to eat single-cell-protein fed animal protein, which would in turn be about 2x as efficient as eating vegetable protein.

I don't think meat eating humans care much if the animal ate plant protein or single cell protein. It's not like meat products specify what the livestock ate throughout its short life.

Even if you have (perfectly valid!) ethical questions about raising creatures as fast as possible only to kill them and harvest their meat; faced with a fellow vegetarian human who cannot be convinced to eat single cell protein, would you convince them to eat SCP-fed animal protein? (better for the environment); or would you convince them to eat vegetable protein? (better for compassion with the livestock creatures)

Assume for a minute you were vegetarian up to this day yourself: you welcome the lower footprint of single-cell proteins, and don't mind eating it most of the time, ... but sometimes you want to treat yourself, just a small treat, would you have the discipline to eat SCP-fed animal protein, or would you insist on eating less efficiently produced vegetable protein?

Le morale: if one is abhorred by the concept of raising creatures for the sole purpouse of eating them, one should stick to the point and not defer to efficiency arguments. Every cover reason backfires... eventually.

It is not just the protein that is a limiting factor in meat production. Especially not for grazing animals. And 20x less seems like a very high estimate compared to the current protein king, the soybean.

What I am saying is: a.sustainable protein will make the largest impact in chicken, but very little impact for the kind of feed and land use we are discussing. Vall and slåtter (I have no idea about the English terms) are almost exclusively used as feed for grazing animals.

And even with chickens I must ask: Is SCP competitive with insects? I have been betting on insects becoming the next big thing in animal feed for some time. 20x less land use per gram of protein compared to soy is no problem for something like the black soldier fly larvae. They are well above 50x.

the costs of grazing land and fence maintenance etc fall away if you can just raise the animals in a cubicle...

you are not explaining where your larvae are getting their proteins... I don't believe they can essentially thrive on CO2 and hydrogen...

When I ate insects I fed them compost. I tried one kind that I could feed rest products from forrestry, but I didn't care much for the taste.

The discussion of SCP in feed is the same as soy beans: we can eat it ourselves. Why accept a 3-10x efficiency loss by feeding it to chicken and pigs? We are already eating SCP, and we are bound to eat more of it in the coming decades.

I said so much myself:

> It will obviously still be 10x more efficient to eat the single cell protein directly than to eat single-cell-protein fed animal protein, which would in turn be about 2x as efficient as eating vegetable protein.

(so you merely reiterate what I wrote) and the paragraph right before it

> We observe it is very hard to convince people to switch from carnivore habits to vegetarian habits. Presumably it will be similarily difficult to convince carnivore population to voluntarily switch to eating single cell protein.

which answers your question:

> Why accept a 3-10x efficiency loss by feeding it to chicken and pigs?

Because citizens enjoy autonomy and the state doesn't force people to eat SCP directly. In the knowledge (not in their defense) that a large group of people eating meat refuse to switch to vegetable protein today, it is naive to think they would however switch to eating SCP directly.

> Edit: and there are ways of maintaining a healthy soil without animals. I have done it in a very small scale for my plantations (just 40m2) and there are examples of people doing it on a much larger scale. I have yet to find data about yields though, but they seem competitive.

Gardening isn't farming. All crop farms of any scale use artificial fertilisers that wash off the land an poison our rivers and wetlands its not sustainable. Cutting out artificial fertilisers and gmo crops would cut our crop production by 60%.

We need to go back to our old style of farming before the world wars where we rotated between crops and animals and used the animals dung as fertiliser.

> We need to go back to our old style of farming before the world wars where we rotated between crops and animals and used the animals dung as fertiliser.

You mean, the old style of farming where our agricultural output was sustained by unimaginable tons of ancient manures looted from South America?

We are already using ~all available animal dung as fertilizer; it provides something like 10% of our global fertilizer needs. We can't produce more animal dung than we are now; we already raise an absurd quantity of livestock, and we especially can't do it while also doing the other thing people suggest on this topic, cutting our meat production by 90%.