There is neither milk nor cattle fodder at a dairy farm. However, if the cows are still alive and you can craft some cattle fodder (requires Cooking 2, Survival 2, and 5 wild vegetables), then you can:
- Move next to a non-hostile cow.
- 'a’ctivate the cattle fodder to feed it to the cow, making the cow friendly.
- 'e’xamine the cow and select the 'm’ilk option, allowing you to transfer up to 2.5L of milk from the cow into a nearby container per day.