No it's not. This is false. First of all, for example, WRT to soybeans, only 20% of the bean can be used to derive oil, which is the ingredient most often used in processed human foods (not the healthiest but I digress). The other 80% of the bean would have to be discarded if not used for meal to feed chickens and pigs [1]. But if the beans do not grow at all you don't get meal or oil. Same is true of corn silage. These parts of the plant are not edible by humans.
But by far the biggest fallacy in your argument is that you don't recognize that animals are eaten by humans and provide valuable nutrition and essential nutrients. If the livestock is dying off because there's not enough feed, there are humans downstream of that who will not be getting fed. Livestock and crops have symbiotic relationship with humans and with each other. A lot of wasted plant matter that humans would have to discard (not to mention grass that cows, deer and other ruminants eat) can be consumed by farm animals. And animal manure can be used as fertilizer to re-invigorate soil and improve crop yields. In addition, animals upcycle crops into higher quality proteins and essential amino acids.
Needless to say though, if our agricultural systems are producing 73% less crops and livestock there will be ~73% less humans.
>The other 80% of the bean would have to be discarded if not used for meal to feed chickens and pigs
No. That is how it is currently used, but in an emergency you could make soy flour, tofu, etc. The calories are consumable even if it's not what we typically eat.
Or, more relevantly, the land that is used to grow soy could instead be planted with corn (or perhaps winter wheat in a post-volcanic scenario). Right now we're planting out crops to optimize for market value, which is driven by livestock feed use. If we instead optimized for human nutritional value, we could easily double output by mostly eliminating livestock (even accounting for the loss of nutrition provided by the livestock).
>Needless to say though, if our agricultural systems are producing 73% less crops and livestock there will be ~73% less humans.
But by far the biggest fallacy in your argument is that you don't recognize that animals are eaten by humans and provide valuable nutrition and essential nutrients. If the livestock is dying off because there's not enough feed, there are humans downstream of that who will not be getting fed. Livestock and crops have symbiotic relationship with humans and with each other. A lot of wasted plant matter that humans would have to discard (not to mention grass that cows, deer and other ruminants eat) can be consumed by farm animals. And animal manure can be used as fertilizer to re-invigorate soil and improve crop yields. In addition, animals upcycle crops into higher quality proteins and essential amino acids.
Needless to say though, if our agricultural systems are producing 73% less crops and livestock there will be ~73% less humans.
1. https://ncsoy.org/wp-content/uploads/11731980513_d53ca2a99e_...