What are Cash Cows and how do they work?

Once unlocked, Cash Cows are permanent sources of Gold income, which generate Gold every minute, up to a set capacity amount. Players can collect the Gold that has been generated at any time and unlock up to 4 additional Cows (other than the one available for Free) to further increase their Gold production and capacity using Gems.

Each additional Cow adds 27,000 more Gold production each 30 days and increases capacity by 300. Cows must be purchased in order, but it's important to note that they all provide the same production and capacity increase.