• usernamesAreTricky@lemmy.mlOP
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    1 year ago

    Grass-fed production doesn’t really scale, so there’s not much way around consumption changes here. It also comes with a side effect of raising methane emissions

    We model a nationwide transition [in the US] from grain- to grass-finishing systems using demographics of present-day beef cattle. In order to produce the same quantity of beef as the present-day system, we find that a nationwide shift to exclusively grass-fed beef would require increasing the national cattle herd from 77 to 100 million cattle, an increase of 30%. We also find that the current pastureland grass resource can support only 27% of the current beef supply (27 million cattle), an amount 30% smaller than prior estimates

    […]

    If beef consumption is not reduced and is instead satisfied by greater imports of grass-fed beef, a switch to purely grass-fed systems would likely result in higher environmental costs, including higher overall methane emissions. Thus, only reductions in beef consumption can guarantee reductions in the environmental impact of US food systems.

    Taken together, an exclusively grass-fed beef cattle herd would raise the United States’ total methane emissions by approximately 8%.

    https://iopscience.iop.org/article/10.1088/1748-9326/aad401/pdf

    • TheButtonJustSpins@infosec.pub
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      1 year ago

      To be fair, pasture raised is more expensive, so people would eat less beef. I don’t think it’s fair to talk about scaling current consumption.

    • abraxas@lemmy.ml
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      1 year ago

      You say that, but it’s not really just about grass-feeding. Cows are already fed almost 90% inedible crop materials that would be getting disposed of anyway. We could be doing better, but cattle’s food source is sorta the wrong focus.

      And as much methane is in manure, it’s better for the environment (including GHG) than synthetic fertilizers.

      The real answer is changing our meat/vegetable balance AND improve the process AND continue to improve humane regulations (and those 3 goals often synergize with each other).

      • usernamesAreTricky@lemmy.mlOP
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        1 year ago

        The % that’s edible is not as relevant as the fact that it still takes much more human-edible feed

        1 kg of meat requires 2.8 kg of human-edible feed for ruminants and 3.2 for monogastrics

        https://www.sciencedirect.com/science/article/abs/pii/S2211912416300013

        Synthetic fertilizer usage is greatly reduced by eating plants directly even compared to the best-case use of animal manure

        Thus, shifting from animal to plant sources of protein can substantially reduce fertilizer requirements, even with maximal use of animal manure

        https://www.sciencedirect.com/science/article/abs/pii/S0921344922006528

        • abraxas@lemmy.ml
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          1 year ago

          The % that’s edible is not as relevant as the fact that it still takes much more human-edible feed

          Not really. Definitely not if you consider the nutritional quality of the meat. And that’s beef, the worst example. (Feed to meat conversion from 6x to 25x, the higher number generally for free-range). Chickens are only x2 in ideal situations (closer to 5x when free-range since their calorie intake is not as well-managed). And from a health viewpoint, 100kcal of chicken is a better-balanced calorie than 200kcal of feed

          But that is before accounting for the fact that about 165 of those feed kcals are inedible, meaning you’re trading around 35 edible kcals of corn for 100 edible kcals of chicken. Would you agree from a purely health and efficiency point of view (leaving out ethics), that 35 edible calories of a “non-nutritional grain” for 100 edible calories of a protein superfood is a pretty fair trade?

          Synthetic fertilizer usage is greatly reduced by eating plants directly even compared to the best-case use of animal manure

          Missed this one, so jumping back. It’s hard for me to respond because I don’t have access to the whole paper. There seem to be fairly significant issues with it, however. For one, I can’t find any corroboration that isn’t merely citing this paper. For another, I can’t find any critical responses either (the lack of them is worse than a half-decent one IMO). Nonetheless, there’s a few things I find interesting from the summary the seem to make it hard to just accept an argument using it

          1. The killer, to me. This paper actively presumes that all crop farms that produce crops that have inedible components that cows will eat (like corn) will pivot to 100% vegetable. But a vast majority of that crop’s output is in explicit demand and corn farms are not just going to fold up. They will start destroying their excess waste instead of reselling it as feed. That ruins his math. But he also failed to take into account what a world horticulture setup would look like that actually sustains humanity, and merely counting IFE is just not enough.
          2. This paper seems to claim a 65% reduction in fertilizer usage, but doesn’t account for the fact it would HAVE to primarily be synthetic fertilizer if we stopped eating cows. This is a huge problem for me because I’m an outspoken advocate of collaborative farming, to reduce the disgusting use of synthetic fertilizer by regulating and enforcing better use of manure and localization of animal farms. There’s far more than 3x as many cows in the world than can be maintained if they aren’t being consumed. He does not cite or comment on how much worse synthetic fertilizer is than manure fertilizer. And if I’m reading right, that’s his high end. It might only be more like 30%. I would rather 100 units of manure used than 70 units of synthetic fertilizer without a second thought.

          And your second link… I’m not sure why you cited it. It appears to be arguing for my side, defending the figures I used. Thank you?

          • usernamesAreTricky@lemmy.mlOP
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            1 year ago

            Cropland usage is still lower when looking at the nutrition of it all

            we show that plant-based replacements for each of the major animal categories in the United States (beef, pork, dairy, poultry, and eggs) can produce twofold to 20-fold more nutritionally similar food per unit cropland. Replacing all animal-based items with plant-based replacement diets can add enough food to feed 350 million additional people, more than the expected benefits of eliminating all supply chain food loss.

            https://www.pnas.org/doi/abs/10.1073/pnas.1713820115

            Further, we can plant other crops on that land growing feed crops. The greatly lower cropland usage offers quite a bit of flexibility to shift around production

            • abraxas@lemmy.ml
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              1 year ago

              Cropland usage is still lower when looking at the nutrition of it all

              I disagree with you and that paper’s abstract. They’re comparing worst-case current aggriculture with a hypothetical improved horticulture.

              Also, I extended my previous post; you might have missed it.

              Further, we can plant other crops on that land growing feed crops

              How do you intend to kill off the demand for those crops? Or do you intend to forbid people and businesses from consuming crops with a lot of feed-waste like corn or soy?