There is indeed a good reason why animal food costs considerably less than human food, and why humans don't resort to eating that cheaper animal food to save money.
To me this is a bold claim. My understanding is eating plants is significantly more efficient per calorie than eating animals on a wide range of scales -- amount of water used, amount of green house gases produced, amount of land consumed. Can you please provide one common example in which a plant humans like to consume is less efficient than a domesticated animal humans like to consume?
It would be worthwhile to define efficiency here, as it can mean a lot of different things, but I'll go with the most readily available numbers that fit within the confines of your comment.
Which means calories to the amount of land consumed. Pork provides 3.5 million calories per acre. Broccoli, only two million calories per acre. For comparison, corn (again, not sweet corn) provides 15 million calories per acre. If you actually ate a corn diet, it would be very efficient, but there is a good reason why you probably don't sustain yourself on a corn diet (those who live on Doritos and sugary drinks excepted). It is not exactly great human food.
Now, that is not the greatest comparison as if you stopped eating pork, you probably wouldn't replace those calories with broccoli, but it does ultimately satisfy your question and illustrates that it is not simply a matter of all plant life always being more efficient. As you can see, corn is really efficient (and not just when it comes to land use), which provides a nice margin for the overall efficiency of animal production.
It records Pork at 672k calories per acre
https://naldc.nal.usda.gov/download/ORC00000242/PDF
EDIT: Another great quote from the PDF "The soy bean.—Soy beans lead all other crops in the production of digestible protein, exceeding corn in this respect by almost exactly 100 per cent. This crop deserves more attention in this country than it has yet received. There is no reasonable possibility of overplanting it. "
Who on earth is eating broccoli for the calories? Assuming 34 calories per 100g that would mean I would have to eat 6kg of broccoli every day to reach 2000 calories. I'm not going to exclusively eat broccoli.
Let's go with a slightly more realistic scenario: I have an absurd love for broccoli and eat 50% corn and 50% broccoli (weighted by calories). 15 million calories50% + 2 million calories50% = 8.5 million calories per acre.
As soon as someone gets less than 50% of their calories from broccoli the Pork starts to look very inefficient.
Animal meat is nowhere near as efficient as eating vegetable crops directly. It concerns me how long you've been spouting your claim with such an elementary error.
What do you mean by vegetable? It is a rather loaded term. Culinary vegetables are definitely not fed to pigs in any meaningful quantities. They are much too inefficient to even consider. If by vegetable you mean any kind of edible plant, then yes, pigs are fed mostly very-efficient-to-produce corn and soybeans.
Based on the numbers before, when you feed pigs 15 million calories of corn (1 acre), they give back 3.5 million calories of pork. If you fed pigs 2 million calories of broccoli (1 acre) then they would likely only give back 0.4 million calories of pork. But that's a really big reason why you don't normally feed pigs broccoli.
> Animal meat is nowhere near as efficient as eating vegetable crops directly
Agreed, if you are talking about the specific vegetable the animal is eating. However, vegetative efficiency varies greatly from crop to crop. If you feed animals the most efficient plants, then they can still be more efficient overall than the less efficient vegetables are alone. As before, the food the animals eat is, for all intents and purposes, not the same food that you eat. Plants that are intended to be fed to humans are generally less efficient to produce, for various reasons.
It sounds to me like he did include the crops fed to pigs in the acreage
If you took the density scale to something really absurd the pig acre efficiency would be the crop times the multiplier as that space converges eventually converges to becomes negligible and just "pig efficency * feed crop calorie/acre" effectively. Granted the effective convergence point may not be realistic without real world data but if factory farms are big enough it comes out to the same order of magnitude as brocoli about 1.5 vs 2. Of course there are a lot of other things to legitimagely object to about said arrangement but it surpringly lines up to be comparable to vegetable crops in caloric efficiency.
A more in depth answer would look at the caloric share of diets in consumption - most people don't get their bulk calories from vegetables.
> Of course there are a lot of other things to legitimagely object to about said arrangement...
The sad reality is that the density scale at pig factory farms is already well past morally objectionable territory if you are concerned at all about animal welfare. I’ve linked resources on this before and can do so again if desired, it’s horrible stuff.
Pigs are about the same as dogs in their sentience and even suitability as a pet. I don’t see how one can justify caring for a dog as a pet and also buying factory-farmed pork once they learn about it. Small farms with better living conditions are arguably more justifiable. I don’t eat animals any more, stopped for different reasons, but being aware plays a role in keeping me from going back.
Well, if you start with 15 million calories worth of corn, feed it to pigs, and you get 3.5 million calories of pork back out, the rest of the energy is exerted to keep the animal alive through its life. The second law is respected.
Meanwhile, an equivalent acreage of broccoli only provides 2 million calories, being far less efficient at converting the environment's resources into calories than corn, so it is starting from behind and never makes up for just how efficient corn really is. The second law continues to be respected.
If you fed that broccoli to pigs, you might not even get half a million calories of pork back, but that's why we don't feed pigs broccoli. Still no violation of the second law.
I am not really sure where you think the violation was meant to occur?
It was asked by a previous commenter in the thread to cherry-pick a crop that is less efficient than a cherry-picked animal. It was never meant to prove anything, only to helpfully answer the specific question asked. Trying to change the subject now does nothing to help your cause, which nobody really disagrees with in the first place. Even if you come from a heartfelt place, it is troubling that you did not take the time to read the thread before pushing your agenda. That is not the type of community HN strives to be.