Study about the nutritional impacts of removing animals from agriculture

[Canastenard]

I just heard about a study: http://www.pnas.org/content/early/2017/11/07/1707322114.abstract

The conclusion says:

This assessment suggests that removing animals from US agriculture would reduce agricultural GHG emissions, but would also create a food supply incapable of supporting the US population’s nutritional requirements.

This is to be fair a bit worrying. That would mean widespread veganism wouldn't be viable if true.

I can't access the full study and I don't think I have the skills to read a scientific study, but here are some numbers in the abstract: animal food provides 24% of calories, about half the proteins, and more than 23% or essential fatty acids in the US diet. They also mention that livestock recycles more than 400000 tons of otherwise inedible human food. For a total amount of food estimated to be higher by 23%, it lowers the overall requirements for essential nutrients.

The authors, Robin R. White and Mary Beth Hall, respectively work at the Department of Animal and Poultry Science, Virginia Tech, Blacksburg, VA 24061 and the US Dairy Forage Research Center, US Department of Agriculture–Agricultural Research Service, Madison, WI 53706. Yet the footnotes say the authors have no conflict of interest. This seems a bit counterintuituve to me that people who work for animal agriculture departments would declare no conflict of interest in a study about the impacts of veganism, but I'm not someone who dismisses studies just because they were done by people whose I don't share ideology, I'd like to see the methodology because that's what matters in science.

The abstract mentions how inedible human food is converted into edible human food by feeding animals agricultural waste. I don't know whether they considered other ways to recycle these, for example yeast/mushroom cultivation or cellular agriculture which intuitively sound more effective to me. I also wonder what they did about sessile animals like oysters that are likely non-sentient; if the study's methodology and conclusion are valid and they excluded them because they're technically animals then that means vegans should get over their aversion to eating flesh of non-sentient animals to make the ethical world they want a possibility.

Edit: there's a detail I missed first when reading the abstract, they mention: "When nutritional adequacy was evaluated by using least-cost diets produced from foods available, more nutrient deficiencies, a greater excess of energy, and a need to consume a greater amount of food solids were encountered in plants-only diets" I realized this when I went to r/vegan on Reddit because I was curious to see people's opinion there. Someone mentioned in a thread about this study that that "least-cost" diet represents 2.05 per day. If they didn't search for a higher budget then the study is actually meaningless because that's so low even for frugality standards.

[ModVegan]

I just heard about a study: http://www.pnas.org/content/early/2017/11/07/1707322114.abstract

The conclusion says:

This assessment suggests that removing animals from US agriculture would reduce agricultural GHG emissions, but would also create a food supply incapable of supporting the US population’s nutritional requirements.

This is to be fair a bit worrying. That would mean widespread veganism wouldn't be viable if true.

I was looking at the same study yesterday (I'd just finished recording a video on two other studies on the same topic with conclusions that seemed conflicting, but weren't).

I found this quote from Men's Health (which was discussing the study) interesting: "The study’s lead author, Robin White, told Science the typical foods vegetarians and vegans use to supplement for the key nutritional elements in meat (stuff like calcium and vitamin A) are not produced at a large enough scale to feed the entire population." (source: http://www.mensjournal.com/food-drink/articles/what-would-happen-if-every-american-went-vegan-w511757)

So apparently, a major part of their conclusion (that plant-based agriculture would be incapable of supporting nutritional requirements) is based on the fact that we don't currently produce vitamins at a large enough scale, which seems a bit bizarre (unless there is some sort of natural limit to vitamin and mineral production that I don't know about).

This study: http://iopscience.iop.org/article/10.1088/1748-9326/aa6cd5/meta claims to have also looked at USDA recommended nutritional requirements and still determined that a plant-based diet works at all levels (though I didn't see much evidence in the study that their attention to dietary requirements was sufficiently rigorous).

One thing I like about the second study I cited is that in some ways it's more realistic: rather than just making a Monte Carlo simulation of an hypothetical vegan world, it posits a gradual shift away from animal products to a vegetarian (leaning vegan) diet. I found this study interesting as well: https://www.nature.com/articles/s41467-017-01410-w (it basically argues that we can feed the world an organic diet, but only if plant-based). I don't think organic agriculture is particularly desirable for a number of reasons, but I did find it gratifying that the study concludes an organic diet is pretty much useless unless it's vegan.

[Canastenard]

I'm posting here because it's relevant, a common argument for animal agriculture is that it helps recycling unedible agricultural waste. For example straw.

Theorically this would be a valid argument if two conditions are met: - we don't produce enough nutrients from edible parts of cultivated plants to supply people's nutritional needs - and animal agriculture increases total amount of enible nutrients. While it's often said that feed conversion ratio of animal agriculture is very poor, the point becomes moot if animals are fed on what would otherwise be wasted.

The first point is suggested by the study I linked above, but as I said in my edit it studies a least-cost diet, and someone suggested on Reddit that the daily budget was 2.05 $. If that's the case then the study is really bad because that's such an unreasonably low budget. Also I know farmed animals still consume a lot of soy and corn, even animals that are fed grass for most of their lives are finished with calorie-rich grain feed. I think it would be interesting to see how much livestock feed is actually agricultural waste unsuitable for human consumption.

An obvious idea of agricultural waste use is composting, but apparently wheat straw makes for poor composting material, being only partly degraded after two weeks: https://www.ncbi.nlm.nih.gov/pubmed/26980627
Straw also has a high carbon to nitrogen ratio, more than ideal in a good compost. This problem could be mitigated by balancing with more nitrogen-rich material in a compost that includes straw, but straw is such a common agricultural waste I'm not sure there would be enough of the rest to balance the ratio, so I can see how feeding it to livestock and getting their manure makes returning organic matter to the soil easier. Even if plant agriculture alone is enough to meet the nutritional requirements of people, it seems important to make sure agricultural soils get enough organic matter for the sake of their fertility (I'm pretty sure systhetic fertilizers aren't enough and healthy soils need organic matter too, an analogy would be comparing soils fertilized exclusively basic inorganic compounds to humans getting the majority of their calories from sugar and oil, is that sound?) And even if we use human waste to fertilize soils, not using fertilizers made from straw (from animal manure or another way) sounds like an important loss of usable organic matter. So that means in a vegan world we should probably find a way other than animal manure to use straw to return organic matter to the soil, at least part of it. Straw can also be used as a source of biofuel which sounds great, but if returning organic matter from straw to the soil is necessary for sustainability then the amount of it that's usable would be limited.

Edit: I found on the EPA website that while treated human feces are indeed used as fertilizer, they say that in the US about 50% of human waste is turned into it, but at the same time they're used on less than 1% of agricultural lands I thought that human waste would have the ability to be a major source of fertilizer, but apparently it could only become a tiny fraction of it. https://www.epa.gov/biosolids/frequent-questions-about-biosolids

8) What percentage of biosolids are recycled and how many farms use biosolids?

About 50% of all biosolids are being recycled to land. These biosolids are used on less than one percent of the nation's agricultural land.

Looks like we really need to find a way to compost agricultural waste if we want another source of organic matter for vegan farms.

[brimstoneSalad]

The abstract mentions how inedible human food is converted into edible human food by feeding animals agricultural waste. I don't know whether they considered other ways to recycle these, for example yeast/mushroom cultivation or cellular agriculture which intuitively sound more effective to me.

They almost certainly did not consider those.

Also, I suspect that in their budgetary analysis they did not consider the effect of animal agriculture subsidies, which is basically the government paying to make non-vegan food cheaper and giving it an unfair advantage.
In this hypothetical vegan world, is the government just burning all of that money instead of shifting those subsidies to vegan food products?

If you look at global production of soy, corn, rice, wheat, etc. and ignore its current use, just look at the main nutrients provided, it's clear that the world's population can be fed on current agricultural yield. We may or may not need to produce slightly more vitamin A or B-vitamin rich foods or supplements, but that's not exactly a monumental task.

Like ModVegan suggested, anything but an overnight shift would be easy to adjust to.

[brimstoneSalad]

Theorically this would be a valid argument if two conditions are met: - we don't produce enough nutrients from edible parts of cultivated plants to supply people's nutritional needs - and animal agriculture increases total amount of enible nutrients. While it's often said that feed conversion ratio of animal agriculture is very poor, the point becomes moot if animals are fed on what would otherwise be wasted.

Not moot if there are other options, as you mentioned a bit before.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3824138/
This study looks at biological efficiency of conversion of straw into mushrooms (in various combinations with cottonseed hulls). The worst rates are around 40-50% for the least desirable combinations.

100g of dry straw yields 40-50 g of fresh mushrooms in the worst cases. And in good cases (for mostly cotton seed hulls) over 120g yield.
Oyster mushrooms are about 3% protein, and contain a ton of B vitamins.

With 100g of yield or better, this is roughly comparable to the crude protein content in the straw:
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/faq7594

You're unlikely to beat that kind of return with any form of animal agriculture... and you're saving that methane production.

This mix was pretty good.

C15 + R75 + WB10 [Efficiency:] 71.6 ± 7.49b

Cottonseed hulls are 6.2% crude protein
Rice straw is 2-7% crude protein (let's assume 4.5%)
Wheat Bran is 15.5% crude protein

That mix probably has about 5.9 grams per 100g.

Getting 2 grams out from mushrooms is pretty good conversion from 5.9 in the substrate.

It's hard to do this comparison for dairy, because they need more protein than that, around 16-17% for good production. ( http://dairy.ifas.ufl.edu/rns/2012/3ChaseRNS2012.pdf )
Feed efficiency seems usually to be around 1.5; so 1.5 pounds of milk per pound of dry feed.

Milk is also about 3 grams of protein per 100g. So, about 4.5 grams of milk protein from 16-17 g crude protein in feed.

2:5.9 for Oyster mushrooms = 34% efficient
4.5:16 for milk = 28% efficient

They're probably about the same. Mushrooms are plausibly better. And definitely better when we consider the environmental implications.
And milk is typically the best case conversion for animal products.
We could compare to eggs, too, but I don't have time right now.

I'll try to respond to more later. You're doing a good job of analyzing this stuff though.

[Canastenard]

Cottonseed hulls are 6.2% crude protein
Rice straw is 2-7% crude protein (let's assume 4.5%)
Wheat Bran is 15.5% crude protein

That mix probably has about 5.9 grams per 100g.

Getting 2 grams out from mushrooms is pretty good conversion from 5.9 in the substrate.

It's hard to do this comparison for dairy, because they need more protein than that, around 16-17% for good production. ( http://dairy.ifas.ufl.edu/rns/2012/3ChaseRNS2012.pdf )
Feed efficiency seems usually to be around 1.5; so 1.5 pounds of milk per pound of dry feed.

Milk is also about 3 grams of protein per 100g. So, about 4.5 grams of milk protein from 16-17 g crude protein in feed.

2:5.9 for Oyster mushrooms = 34% efficient
4.5:16 for milk = 28% efficient

They're probably about the same. Mushrooms are plausibly better. And definitely better when we consider the environmental implications.
And milk is typically the best case conversion for animal products.
We could compare to eggs, too, but I don't have time right now.

I'll try to respond to more later. You're doing a good job of analyzing this stuff though.

So you're saying that since agricultural waste has a lower protein ratio than ideal for animal agriculture (although wheat bran comes close) we can't exclusively feed dairy cows that waste because there isn't enough protein to be profitable, right? Which would imply grains and soy that could easily become human food is a mandatory part of a dairy cow's diet. In that case then the "farmed animals increase the amount of usable nutrients" claim doesn't hold up to scrutinity, unless said amount of grains and soy represents a very tiny part of the animal's diet (it probably doesn't). Edit: just to make sure I'm not accidentally cherry picking by limiting myself to what you presented, I searched and found leaf protein concentrate: https://www.feedipedia.org/node/77

And asides from mushrooms, what about yeast? Nutritional yeast is a staple in many vegans' diet including mine, but I read it is usually made from molasses of sugar beet and sugarcane, and there's also malted yeast which is made from malted barley, in other words from grain that could directly be fed to humans rather than processed by another organism's biology, so it doesn't seem to promote use of agricultural waste much. I tried to search for yeast grown with agricultural waste, but what I find is about biofuel, not human food. Still, the conversion is probably more efficient than animal agriculture.

As I mentioned animal agriculture is also a way to transform agricultural waste into manure, which can be used as a fertilizer to give soils the organic matter they need to be healthy and productive. I know we already discussed that in an earlier topic, but I don't think we discussed the specific point of recycling agricultural waste. In a world without animal agriculture we should probably find a way to transform agricultural waste into organic matter without making it pass through an animal's digestive track. Thus composting could probably actually become its own sector in a vegan world, and be optimized to release the least methane possible. I don't know how much more difficult or easy plant-only waste is to compost compared to other compost that also includes animal feces (although manure is a good source of nitrogen which can be a limiting factor in composting, so we should find something else, clover and alfalfa would work, maybe even synthetic ammonia?) but I'm pretty sure it would be a win overall because it looks more efficient (a lot of organic matter is lost by breathing in the animal's lifetime) and would have less potential for dangerous pathogens.

For what I know the role of supplying organic matter to the soil is to promote the life of small animals like worms and insects, which aerate it and help making nutrients more available for plants.

The study I linked looked at wheat straw, but actually didn't suggest that all straws are bad for composting, for example saying that maize is better composting material:

These results indicated that comparing with maize straw, wheat straw was an inefficient substrate for rapid natural lignocellulose-based composting, which might be due to the recalcitrance of wheat straw.

That would means some agricultural waste would be composted, and other would find other uses. However that also means we wouldn't return all the organic matter from agricultural waste to the soil... but do we need to? Since agricultural fields are not closed systems and interact with the outside, I guess they get some of their organic matter from the outside too? (Like wild insects who move and die in agricultural fields) That would also mean different kinds of straws could serve different uses, for example if wheat straw is bad for composting we can use it to produce biofuel instead.

[brimstoneSalad]

And asides from mushrooms, what about yeast? Nutritional yeast is a staple in many vegans' diet including mine, but I read it is usually made from molasses of sugar beet and sugarcane, and there's also malted yeast which is made from malted barley, in other words from grain that could directly be fed to humans rather than processed by another organism's biology, so it doesn't seem to promote use of agricultural waste much. I tried to search for yeast grown with agricultural waste, but what I find is about biofuel, not human food. Still, the conversion is probably more efficient than animal agriculture.

Human edible products can be produced from waste, I just don't think any nutritional yeast is currently since sugar is very cheap.

Ethanol production has high protein yeast matter as a byproduct, "Distillers grains", we just don't eat it. It's currently fed to animals, but there's no reason it could not be processed into human food.
https://en.wikipedia.org/wiki/Distillers_grains

Sugar is cheap because it's an incredibly efficient crop (better than corn or pretty much anything else).
The conversion there is going to be much better than that for animal agriculture, even if you used corn products.
There's no reason to believe human diets could not be easily supplemented with nutritional yeast at a better efficiency than animal products.

The complaint of this study was that while we have more food we end up with excess carbohydrates based on what we're currently growing, but this really isn't an issue since we can use them for SCP feed stock.

They also complained about some lesser nutrients, which is pretty silly since many foods are already fortified. If we don't have enough carrots to give everybody enough vitamin A, that's not an issue that's even difficult to solve.
They claim we can't grow more vegetables without it being more expensive, but that's bullshit if you consider how they rely on government subsidies to make animal products as cheap as they are. I'd like to see an analysis honest enough to shift those subsidies to vitamin rich vegetables.

I know we already discussed that in an earlier topic, but I don't think we discussed the specific point of recycling agricultural waste.

Right, but the thing is even if you ignore the agricultural waste, there's plenty of corn and soy to feed everybody. The only issue is the poorer nutrient ratio in corn (easily fixed by processing or conversion by yeast rather than by animals).

Then we can use the straw which would be wasted to grow mushrooms and produce ethanol.
I'm not sure if we'd want to eat that distillers grain, but it could be processed into something edible particularly if we could remove the purines:
https://www.researchgate.net/publication/23127601_Chemical_methods_for_the_reduction_of_the_purine_content_of_baker%27s_yeast_a_form_of_single-cell_protein
Or we could just process it into fertilizer... or add it to mushroom substrate.

For what I know the role of supplying organic matter to the soil is to promote the life of small animals like worms and insects, which aerate it and help making nutrients more available for plants.

It's mostly for the nitrogen and phosphorus. Decomposition releases these things slowly to provide the necessary elements plants need to grow.
When we remove plants from the field and eat them, we remove these elements.

However that also means we wouldn't return all the organic matter from agricultural waste to the soil... but do we need to? Since agricultural fields are not closed systems and interact with the outside, I guess they get some of their organic matter from the outside too? (Like wild insects who move and die in agricultural fields)

Insects would also eat things in your fields, and leave the field and die somewhere else.

The source of new elements in the field comes from deep in the soil, from breakdown of rock. Deep rooted plants can pull things up from down below. Thus the appeal of agroforestry and alley cropping. The leaves that fall from trees bring up minerals from very deep in the soil where superficial crops have no access to them.

[Canastenard]

And asides from mushrooms, what about yeast? Nutritional yeast is a staple in many vegans' diet including mine, but I read it is usually made from molasses of sugar beet and sugarcane, and there's also malted yeast which is made from malted barley, in other words from grain that could directly be fed to humans rather than processed by another organism's biology, so it doesn't seem to promote use of agricultural waste much. I tried to search for yeast grown with agricultural waste, but what I find is about biofuel, not human food. Still, the conversion is probably more efficient than animal agriculture.

Human edible products can be produced from waste, I just don't think any nutritional yeast is currently since sugar is very cheap.

Ethanol production has high protein yeast matter as a byproduct, "Distillers grains", we just don't eat it. It's currently fed to animals, but there's no reason it could not be processed into human food.
https://en.wikipedia.org/wiki/Distillers_grains

So it looks like there's actually higher protein agricultural waste than I thought, which makes my point "animals are fed grains for a higher protein diet" not really valid. The reason why livestock is fed grains and soy grown specifically for them is probably because of the overall demand for animal products, because I'm sure if the animal agriculture industry could feed all its animals only agricultural waste it would.

The complaint of this study was that while we have more food we end up with excess carbohydrates based on what we're currently growing, but this really isn't an issue since we can use them for SCP feed stock.

They also complained about some lesser nutrients, which is pretty silly since many foods are already fortified. If we don't have enough carrots to give everybody enough vitamin A, that's not an issue that's even difficult to solve.

Key word seems to be "currently" here. Although animal products are an important source of fat in the current western diet, there are plant sources of fat too, and we should probably increase the overall production of fatty plant food to provide people their nutritional needs (we don't want the entire population to buy into the "high carb low fat" mantra, right?) Not even counting things that grow on trees, we have sunflower, flax, camelina, hemp and canola which can be cheap sources of plant fat that can grow in temperate climates; soy is also fairly high in fat. Although we would probably also have to increase our production of fat from trees, for example walnuts. As you suggest planting trees in agricultural fields for the advantages they provide, maybe we could get at least part of our increased demand for nuts from grain and legumes agricultural fields that also include trees that provide nuts.

I'm not sure if we'd want to eat that distillers grain, but it could be processed into something edible particularly if we could remove the purines:
https://www.researchgate.net/publication/23127601_Chemical_methods_for_the_reduction_of_the_purine_content_of_baker%27s_yeast_a_form_of_single-cell_protein
Or we could just process it into fertilizer... or add it to mushroom substrate.

Most of the results I find when I try to find uses for distillers grain is about animal feed, but by trying I can find pages that talk about using it as fertilizer, here's a study for example: https://pdfs.semanticscholar.org/93c1/02c2c596a6aef8072f8d81d90fcab3e36df0.pdf

I'm too lazy and also not experienced enough to correctly interpret a scientific study, but here's the conclusion:

The results of these field studies indicate that DDGs may be utilized as a fertilizer source for corn production. However, agronomic performance was dependant on rainfall and growing conditions during the year. Grain yield increased 1.41 and 1.56 kg ha-1 for every kg ha-1 of DDGs that were applied in medium and high yield environments, respectively. Corn raised in low yield environments did not respond to increasing DDG rates while PCU or anhydrous ammonia increased grain yields in these environments when compared to DDGs. Application rates of DDGs may need to be higher to attain grain yields equivalent to other N sources when surface applied. In this research, DDGs did not affect large seeded broadleaf weed or corn development, SOM, P, K, Ca, or Mg concentration. There was a decrease in soil pH when DDGs were applied at 3600 kg ha-1. Additional research is needed to identify consistent systems that provide responses to DDGs as a fertilizer source in low and medium yield environments if the cost of DDGs is low enough to be used as a fertilizer source for corn. This may require management changes, such as supplemental synthetic N fertilizer applications at reduced rates (N’Dayegamiye, 2006; Rashid & Voroney, 2005;) or incorporation (McDade & Christians, 2000) to achieve yields similar to conventional N fertilizer sources.

Looks like distillers grain can be used as fertilizer, but doesn't work as well in low yield fields compared to synthetic ammonia.
As a protein rich product, my intuition told me that it is rich in nitrogen since that element is present in all amino acids, which for composting would be useful to balance the high C/N ratio of some agricultural waste if we don't use all of it for ethanol production. Apparently that's the case, which would make it a good manure substitute as a nitrogen source for composting. Here's an extrait of the abstract of a study that strongly suggests it: http://hortsci.ashspublications.org/content/43/1/191.full

Addition of 20% DDGS decreased the C:N ratio from 90:1 to 24:1 for the potting mix and from 23:1 to 10:1 for a soil.

However the study also mentions an herbicidal activity of DDGS, which would mean it would have to be used carefully to not have an effect contrary to intended on crops. Further research confirmed the potential herbicidal activity of DDGS, I'll link to an example of a study: http://cdn.intechopen.com/pdfs/20070/InTech-Fertilizer_potential_of_biofuel_byproducts.pdf

Another reason why organic growers may be in terested in DDGS is the potential for weed suppression.A small number of studies of have identified weed suppression characteristics in DDGS, although the mechanism is poorly understood at this time (Boydston et al., 2007; Liu and Christians, 1994). While it has been shown to be only a mildly effective herbicide, organic growers may still be interested in these properties since options for certified organic herbicides are extremely limited.

The paragraph mentions organic farming, but I want to make it clear that's not the widespread agriculture I envision because of its restrictions based on "naturalness" rather than evidence. I wonder if its herbicide effect could be of any worthwhile use in conventional evidence-based sustainable vegan farming though. It's apparently less effective than things like glyphosate, but if its herbicidal effect is of any significance then we can't say no to more different kinds of weed control methods to prevent being powerless against resistant ones.

tl;dr Sustainable vegan farling can be done by reusing agricultural waste for growing mushrooms, producing ethanol for biofuel, and compost material. Producing ethanol also comes with a byproduct, distillers grain, which can be used as a fertilizer as well as a nitrogen source to balance the C/N ratio of compost. We should also plant trees in agricultural fields because of the advantages they provide, like lower impact of erosion, mineral fertility, nitrogen fixation (if the trees are legumes), increased carbon sequestration, and potentially offering a new source of fruits and nuts. Because that system would produce biofuel, it would reduce the needs for fossile fuels.

How good/evidence-based all of that sound?

[brimstoneSalad]

We should also plant trees in agricultural fields because of the advantages they provide, like lower impact of erosion, mineral fertility, nitrogen fixation (if the trees are legumes), increased carbon sequestration, and potentially offering a new source of fruits and nuts. Because that system would produce biofuel, it would reduce the needs for fossile fuels.

There aren't many deep rooted legumes or legume trees people would want to eat. It's probably better to prioritize food producing trees, and rely on legumes grown under the trees (and in other fields harvested as green manure) for nitrogen.

[Canastenard]

If there aren't many legume trees that are a good source of food too, then yeah I can understand how we can prefer getting more fruits and nuts over fixation from trees. I know the carob tree is a legume that produces something that can be processed as food or additive, but a research on Wikipedia shown me that it doesn't have nitrogen fixation capabilities unfortunately (plus it only grows well in relatively warm climates anyway).

Anyway, I've added some infos on the section of Plant agriculture named "The role of trees in sustainable farming", and while I haven't put a source directly on the page yet I've found an excellent document made for the French ministry of agriculture I'm posting here: http://agreste.agriculture.gouv.fr/IMG/pdf/analyse371201anglais.pdf

... and now I feel like this topic has become my Wiki page's equivalent of the "Nutrients of Concern in progress" topic in this section rather than what is originally was about (a specific study).