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In reply to the discussion: Red meat plays vital role in diets, claims expert in fightback against veganism [View all]muriel_volestrangler
(101,307 posts)There is no doubt at all that the higher the proportion of meat in a diet (especially of ruminants that produce methane), the more greenhouse gases come from its production. This comes from the basic mathematics of keeping animals alive for a significant amount of time on plants, rather than using the plants directly. And in practice, the other things you mention, like pesticides and fertilisers, get used on animal fodder too.
"I suspect the energy used to process one acre of canola into oil is more than the energy used by a pig to make 10 gallons of fat. I have seen studies that suggest this.....unfortunately it had not been experimentally studied."
The yield from canola is " about 95 to 240 gallons of oil per acre", so comparing one acre to one pig is irrelevant.