> I don't have any fixed evidence or numbers, but recalling my youth working on a 200 - 250 cow dairy, the animals were strip grazed in paddocks during the day

> I don't have any fixed evidence or numbers, but recalling my youth working on a 200 - 250 cow dairy, the animals were strip grazed in paddocks during the day and night. They would therefore mostly defecate in the paddock, on the grass, spread across a wider area and acting as a natural fertiliser. This is something the author mentions in passing: Almost everywhere, farms are required by law to have a certain amount of land per piece of cattle to spread the manure on. So as long as that certain amount of land is large enough and the spreading happens sufficiently often, there shouldn't be a problem. If there is a problem, current regulations need to be updated. That land requirement will also naturally limit the total amount of cattle that is being raised.