This is topic of high emotional content, and I applaud what I perceive as your effort to promote rational discussion. The core question, or so it seems to me, is not "how" but "whether" animals ought to be raised for food. If the question of "whether" is answered in the affirmative, the question of "how" is essentially relegated to the area of effectiveness. Determination of animal density (biomass per unit area) in cultural systems is a process of optimization, which may or may not mean maximization, largely determined by the species being cultured. Increased densities have both problems and advantages, and resolution of the pertinent questions is often site or case specific.
And then there are the really murky questions, such as: how do we decide which species we wish to get excited about? Good luck.