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It's true that most of the food consumed by livestock isn't edible by humans - [0] says 86% - but livestock are so inefficient at converting food to edible nutr

It's true that most of the food consumed by livestock isn't edible by humans - [0] says 86% - but livestock are so inefficient at converting food to edible nutrition that they still generally consume more than 1 human-edible Calorie per Calorie of meat produced. For cattle, Diet for a Small Planet [1] cites 16 Calories per edible Calorie of meat and 8 grams of protein per edible gram of protein produced, other sources seem to be in the same ballpark - both higher than the ~7:1 ratio that's implied by that 86% figure. The ratios for chickens are better, but they also generally get a much lower share of their feed from human-inedible sources. Also, even that 86% isn't "free" - it's not all pasturing, and it takes a lot of effort, energy, and equipment to get hay, inedible by-products of human-edible crops, etc. from the field to animals' mouths. [0] https://www.cgiar.org/news-events/news/fao-sets-the-record-straight-86-of-livestock-feed-is-inedible-by-humans/ https://www.cgiar.org/news-events/news/fao-sets-the-record-s... [1] https://www.amazon.com/Diet-Small-Planet-20th-Anniversary/dp/0345321200/ https://www.amazon.com/Diet-Small-Planet-20th-Anniversary/dp...

iammisc 5y ago
> cites 16 Calories per edible Calorie of meat and 8 grams of protein per edible gram of protein produced. Two things. Firstly, those are 16 Calories that would otherwise quite literally go to waste. They would be metabolized by bacteria, used to grow a bacterial mat in a compost bin, and then be released into the air in the form of CO2. Secondly, I'm not sure what 8g of protein per edible gram of protein produced means. Ruminants like cows convert carbs and other compounds into protein by hosting gut bacteria. Without a cow or chicken or something in between, these amino acids would have to come from somewhere else. Same with B12.
- rapind 5y ago
  Don’t we grow food specifically for livestock though? That must consume a lot of resources (oil, water, etc). I think the argument is the cut out the middle man (beef / chicken) due to inefficiencies. I personally suspect the real ratio is less than what’s being cited just because I’m a cynic, but there seems to be some logic to it no?
  - frankus 5y ago
    > Don’t we grow food specifically for livestock though? I think that’s the central point of this thread where folks are talking past one a other. In a hypothetical scenario where animals are more or less only eating food that humans can’t, it makes a lot of sense (from an environmental if not ethical standpoint) to include animals in the mix of foods people eat. The impression I get is that in reality, animals grown for meat consume quite a bit of human-edible food (or food that could be trivially replaced with human-edible varieties), although I have no idea of the actual percentage.
  - maxerickson 5y ago
    Yes, lots of agriculture is growing animal feed. Animals get feds lots and lots. Here's a description of finishing cattle, from a beef marketing perspective: https://www.highlandcattleusa.org/content/Grain%20Finished%20Beef.pdf https://www.highlandcattleusa.org/content/Grain%20Finished%2... Casually talks about feeding cattle their weight (or 2x) in corn over the last 3 months of their lives.
- tfehring 5y ago
  I agree that 86% of those Calories would otherwise go to waste. But considering how bad animal agriculture is for the environment just in terms of direct impacts, I doubt that feeding them to animals is an improvement over the alternative you mentioned, and I highly doubt that it's the optimal solution across all the potential alternative disposal methods we could come up with. The plants that cattle and many other livestock eat - including grasses, corn, and other feed crops - contains protein. The exact amount depends on the plant, its age, and growing conditions, but it's often 10 to 15% by mass. Cows apparently consume about eight grams of protein for every gram of protein that makes it to humans' plates, with the rest of the amino acids presumably making up inedible organs and/or being used for bodily functions while they're alive.

iammisc 5y ago

> cites 16 Calories per edible Calorie of meat and 8 grams of protein per edible gram of protein produced. Two things. Firstly, those are 16 Calories that would otherwise quite literally go to waste. They would be metabolized by bacteria, used to grow a bacterial mat in a compost bin, and then be released into the air in the form of CO2. Secondly, I'm not sure what 8g of protein per edible gram of protein produced means. Ruminants like cows convert carbs and other compounds into protein by hosting gut bacteria. Without a cow or chicken or something in between, these amino acids would have to come from somewhere else. Same with B12.

rapind 5y ago
Don’t we grow food specifically for livestock though? That must consume a lot of resources (oil, water, etc). I think the argument is the cut out the middle man (beef / chicken) due to inefficiencies. I personally suspect the real ratio is less than what’s being cited just because I’m a cynic, but there seems to be some logic to it no?
- frankus 5y ago
  > Don’t we grow food specifically for livestock though? I think that’s the central point of this thread where folks are talking past one a other. In a hypothetical scenario where animals are more or less only eating food that humans can’t, it makes a lot of sense (from an environmental if not ethical standpoint) to include animals in the mix of foods people eat. The impression I get is that in reality, animals grown for meat consume quite a bit of human-edible food (or food that could be trivially replaced with human-edible varieties), although I have no idea of the actual percentage.
- maxerickson 5y ago
  Yes, lots of agriculture is growing animal feed. Animals get feds lots and lots. Here's a description of finishing cattle, from a beef marketing perspective: https://www.highlandcattleusa.org/content/Grain%20Finished%20Beef.pdf https://www.highlandcattleusa.org/content/Grain%20Finished%2... Casually talks about feeding cattle their weight (or 2x) in corn over the last 3 months of their lives.
tfehring 5y ago
I agree that 86% of those Calories would otherwise go to waste. But considering how bad animal agriculture is for the environment just in terms of direct impacts, I doubt that feeding them to animals is an improvement over the alternative you mentioned, and I highly doubt that it's the optimal solution across all the potential alternative disposal methods we could come up with. The plants that cattle and many other livestock eat - including grasses, corn, and other feed crops - contains protein. The exact amount depends on the plant, its age, and growing conditions, but it's often 10 to 15% by mass. Cows apparently consume about eight grams of protein for every gram of protein that makes it to humans' plates, with the rest of the amino acids presumably making up inedible organs and/or being used for bodily functions while they're alive.