How does harvesting animals cause less suffering, in the real world we live in? The usual answer is "well IF you are friends with your cow/chicken and give it lots of pasture and then you squeeze it for milk occasionally and one day quickly and painlessly end its life, then its humane" but then motte-and-bailey--style that gets used to excuse a diet full of factory-farmed meat and chicken trucks and forcibly-impregnating cows and then seizing and killing their newborns[1], which is the vast vast majority of meat consumption.
[1] https://www.google.com/search?q=chicken+trucks&source=lnms&t...
[2] https://www.ciwf.com/farm-animals/cows/dairy-cows/