Interestingly enough, this question coincides with “How was the cow domesticated?”

A little bit of context, the cow (aurochs) before domestication was an absolute brute. They were violent beasts much larger than humans and much larger than the modern cow. So how the heck did it get domesticated???

Well humans didn’t choose to domesticate the cow. It was a symbiotic relationship that developed because both sides learned about the benefits of keeping each other around which develops a tolerance between each other and eventual direct interaction. But that still doesn’t go all the way. Why the heck would humans tolerate such a beast??? (Some surviving documents from Rome/Greece reference the aurochs as an untamable beast. I can track those down if you’re interested. But the aurochs survived until the 1600s while cows were already domesticated.)

So! If we need them to hang around each other for long enough to realize that they benefit from each other, then what could bring them together in the same place?? WHEAT!

In Ancient Rome it was punishable by death to let your cows eat from the wheat fields of another farmer... except for certain months of the year. The months of the year where the wheat’s seeds haven’t sprouted yet and we’re just leaves.

Why? Because the cows would eat the leaves, allowing the wheat to reserve their energy for growing seeds (the substance humans were interested in). This was a practice that was developed well before the cows were domesticated (aurochs at the time), and continued through Rome (recorded in agricultural guides which I can also track down if interested) and the medieval world.

So to sum it up/tl;dr: A practice of ancient civilizations through the Middle Ages to optimize wheat yields were to have cows eat the leaves off of wheat before the seeds sprouted. This meant the wheat plant would have energy exclusively for growing the seeds which made more larger yields.

Sorry for grammar mistakes, I’m at work typing frantically.