Cow auctions

With this system, cow owners earn solana periodically by holding an auction to decide which DNA owner will get the chance to breed her for a cycle.
Every cow holder can initiate the auction by setting an auction length and a reserve price, and have the right to end it by accepting a bid at any time. Once a winner is decided, they send the Solana to the cow owner, burn the DNA used to bid, and will receive a calve representing both of the parents' rarity after a maximum of 14 days.
The pregnancy time can be reduced by having a cow with attributes on her (a day reduction for each), or by starting the auction with a doctor accompanying her.