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Eating meat is inefficient. With each step in the foodchain you lose anywhere between 50 to 90% of the energy. So as a human trying to be efficient you want to have the least steps between you and the meat you eat. A plant like grass has to be eaten by a vegetarian creature and then you can eat the creature. With each step in between the size of the area the plants grow in needs to be bigger to compensate for the losses.

In my language we have a plant that translates to “meat tomato”. Which gave me the idea: what if you could alter plants enough to grow fruits with actual meat in them? Yes the plant would need to spend some energy keeping that meat alive until the fruit is collected, but it would circumvent the need to be digested by an intermediary animal which uses energy to digest it and move around looking for food or even doing something like sleeping.

So my question: compared to a single animal eating your food first, how efficient could a literal meat plant be?

Disclaimers:

  • the plant is a plant, only its fruit is meat (unless you can give a good reason for more of it to be meat). The fruit could have an outer plant-shell for protection if that helps keep the energy cost of keeping it alive down.
  • I am not looking for alternatives to the meatplant. I do not need answers like “but growing X or Y would be more efficient” or “Z is already a good meat replacement”. These people want to grow meat, with plants. Not have meat replacements.
  • you can express the efficiency in square area required to grow a certain amount of meat. Lets say 10kg of meat. You can use any other amount if that is easier so long as it can be transformed to an understandable square area to meat ratio.
  • The intend is to grow a variety of meat types. However the any single type of meat that you can find data about will suffice, this in the interest of making it easier to find an answer.
  • I assume that exact numbers will not be possible, a ballpark number is OK.
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  • $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Mar 30, 2023 at 7:42

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500-1000 lbs per acre is a safe estimate.

this should be possible, too be safe I will stick to low end estimates. Also I am assume modern farming for lower tech levels you will need ot make some adjustment.

It should be way more efficient than any animal, but lets check. There are already high protein plants like beans, it is more a matter of structure than protein content to get meat.

Beans can yield around 1500 lbs per acre so that is your best place to start.

Beef contains about 2-3 times the protein than beans so if you want to be safe say you only get 1000-500lbs of meat per acre. that is the the same range as cattle so not too bad.

Now beans are not fruit and fruit trees can have huge yields compared to beans. 6000 lbs of apples or avocado per acre is normal if not a low estimate. They have very different protein contents but similar yields, that means protein content is likely not a limiting factor on fruit yield. So you should still be fine with higher yields.

you are looking at some high end genetic engineering, some really weird selective pressures, or magic but it is believable.

A second way to consider it

Avocado is 2% proteins by weight, meat averages 22% protein by weight , so divide avocado production by 11 and you have a decent estimate of meat tree fruit production.

6000 to 11000 lbs. per acre divide by 11 that gives 540 to 1000 lbs per acre.

two different methods give us similar amounts so these should be pretty solid estimates short of a full on study.

Considerations, what do you mean by meat.

Now protein content differs a lot in meat from different animals, I used an average of 22%. A low protein meat like duck is only 12% protein so you could get twice the yield. While an extremely high protein meat like chicken is 36% protein so you would only get half the yield.

enter image description here

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  • $\begingroup$ Like the idea of tweaking the amino-acid profile of avocados so it's complete and balanced for humans (if the OP has genetic engineering). Chuck in lots of vitamins too for good measure. Employ decent chefs to prevent monotony. $\endgroup$ Mar 29, 2023 at 1:43
  • $\begingroup$ Its a good answer but I still have questions: you mention that cattle can get 500 to 1000 pounds of meat out of an acre. But that includes the 50 to 90% energy loss of the cattle eating the plants. Wouldn’t that mean the actual energy content could be at least twice as high? $\endgroup$
    – Demigan
    Mar 29, 2023 at 6:40
  • $\begingroup$ Upvote just for the awesome picture. Where do these trees grow? $\endgroup$
    – quarague
    Mar 29, 2023 at 13:23
  • $\begingroup$ @AngryMuppet IIRC, corn and beans are missing only one amino acid. It's one that you don't need as an adult but do as a child. Golden rice is a gene eng thing with vitamin A. If that, then maybe one extra amino acid in corn isn't unreasonable. $\endgroup$
    – Boba Fit
    Mar 29, 2023 at 13:44
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    $\begingroup$ @BobaFit already done rutgers.edu/news/… $\endgroup$
    – John
    Mar 29, 2023 at 20:14
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A couple of cow facts (which were hastily googled but should be a serviceable baseline):

  • A cow takes about an acre / 4,000 square meters of grazing land.
  • A slaughtered cow carcass weighs in the vicinity of 1100 lbs / 500 kg.
  • Cows are typically slaughtered at about 2-3 years of age.

So the natural ratio of plant surface area : cow is about 8 square meters per kg every 2 years, not bad. A typical full-sized apple tree has a roughly circular canopy of roughly 30-40 foot diameter - call it 10m, for a surface area of about 80 square meters.

That suggests that at a rough estimate, if you took an apple tree, genetically modified it to generate proteins, and concentrated them into "meat apples", you could get a yield of 10 kg of meat per 2 years, or 5 kg per year. That's not a lot for a tree - a full-sized tree can yield 300-400 kg of apples - but it may be suitable.

Now, the parts I'm glossing over:

  • A 500 kg carcass is not 500 kg of meat; depending on how you butcher it, it's more likely around 350 kg of meat. I've elected to ignore this because as you point out, the meat tree doesn't need bones, joints, or other parts.
  • An apple tree doesn't just spend its energy producing apples. I'm assuming though that in a mature tree that doesn't grow much year to year, the amount of energy that goes into fruit is similar to the amount of a cow's energy that goes into meat. (Both of them will also spend energy on sustaining themselves.)
  • Although the meat tree doesn't have to digest its own cellulose and fructose, it does have its work cut out for it metabolically speaking. There's a lot of chemistry involved in producing new protein from nothing, which is why most plants don't do it if they can avoid it. You may need a symbiotic helper, akin to the nitrogen-fixing bacteria in legumes, to help meet the tree's nutrient needs - this will take more energy. Synthetic fertilizer will also be of great help.
  • Once the tree has a steady supply of protein, it needs to make it into defined muscle tissue (if you wanted bulk protein you could just plant peanuts and have done with it). There are fruits with quite complex structures and chemistry so I assume this isn't implausible but it probably comes at a cost in energy as well.
  • Meat fruits would probably go bad a lot faster than regular fruits once they're ripe, so you'd want to be diligent about picking them.

Tl;dr: 10 kg/year could be the yield of a couple of normal-sized fruit trees. Call it 50,000 kg/year for a square kilometer.

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  • $\begingroup$ you could compare peanuts, legume or other high protein plant products instead of assuming a cow (a low yield animal at that) is a good metric. $\endgroup$
    – John
    Mar 29, 2023 at 0:20
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    $\begingroup$ @John If they wanted protein, OP would have said protein. They want meat, and meat is going to come at a cost compared to the bulk stuff. $\endgroup$
    – Cadence
    Mar 29, 2023 at 0:23
  • $\begingroup$ do you thing beans are solid protein? both are living tissue, why would it come at a higher cost? $\endgroup$
    – John
    Mar 29, 2023 at 0:31
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I think that it's reasonable to say it's just as efficient as any other plant. If your plant can grow meat then it can grow meat efficiently. It will have evolved the right enzymes, grow in the right soil and be part of an ecosystem that allows it to prosper.

It may enjoy interesting sympiotic relationships or capture additional nutrients through consuming insects or whatever.

It may have to rely on a novel evolutionary story, but there is plenty in the natural world that if we didn't havve it to look at we wouldn't believe it could happen.

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