Because beef uses feedlots with grain as well, and have the same manure lakes. The beef industry has figured out that cattle fatten up far faster on grain, so

Because beef uses feedlots with grain as well, and have the same manure lakes. The beef industry has figured out that cattle fatten up far faster on grain, so they leave the cattle out for I think it's 12 months to basically grow to their "adult" size, then put them on grain for a few months to fatten up. They have it precisely timed, because the cattle basically die on the all grain no silage diets they get, or would if they don't get sent to the abattoir literally a fortnight before.