animal husbandry could get you way more food per animal in a generation

My dissertation chairman was involved in a research project in India back in the 1960s. Some agricultural extension folks had gone there because they had assessed Indian cattle as "weak" and "sickly" and were trying to introduce American breeds as a substitute. The locals wanted no part of these animals and eventually the researchers tried the radical approach of asking them why not. Turns out that while these cattle could plow 50% more land in a day, they ate twice as much food as the Indian breeds.

The light went on in their heads and they set about attempting to cross American cattle with Indian cattle and breeding the most efficient animals. Turns out they couldn't get any more efficient than the original Indian breeds.