So as far as I understand it, to get fertilizer I need to collect the cow droppings after they eat the tall grass. Problem is: They jsut stand in the grass with an exclamation mark above their heads instead of eating it.
Picking them up and moving them or cutting the grass and letting it regrow doesn't change anything :/
I'm on v5.

When cows have an exclamation point over their head it means they are "full" milking them with a wooden bucket will make them slim and hungry again, although I wish that over time they slimmed down by them self after a while since not having enough milk storage  could halt seedlings since they now require fertilizer. 

Hey, uhhh, what do I do with the buckets of milk now? Should I just make a new bucket for every time I need to milk a cow? Sorry if this is obvious, I'm a noob