The Farmer's complaint reminds you that your royal herd of milking cows was also decimated by the plague, so you might as well solve your problem and the Farmer's at the same time.... Okay so your not really going to solve the Farmer's problem, but yours are the only ones that matter.
"Very well!" You Proclaim. "I will solve your problem. You will now have all the milk you could ever want."
When the Farmer hears your words his face brightens with joy (You love this next part) and immediately darkens with not only black spots of fur but with pure terror as well. Because he and his wife now have extremely large cow udders brimming with fatty milk hanging down from their bellies and dangling past their knees.