In the 14th century, the Black Plague had a much larger impact on agriculture than anything else. At least this is the book I could easily lay my hands on. Chapter 2, The Agricultural Revolution. Noette's theory was that the Greeks and Romans had never found the correct way to harness horses but had simply adapted the yoke harness of the ox, with minor modifications, to the horse. The horse, like the tractor that superseded it, was certainly not adopted everywhere and at the same time.
Horses also have greater endurance and can work two hours longer per day in the fields.
And as a further advantage, it allowed farmers who wanted to plow with horses to have a spring crop of oats, which would feed the horses. There is more, but I'm tired of typing this in. Perhaps this gives an idea of what I am basing my statements on. I would like to see you get a dozen eggs or a pound of chicken from one pound of wheat and nothing else. I seriously doubt you could do this today, at least not for a sustainable time period.