Night was removed in a previous patch.
To feed and fatten them, make milkshake by grinding ice from the store and mixing it with milk, which you can get from milking the kobolds.You can make the milkshake more effective by adding banana too!
It actually almost doubles the calorie intake with MilkShakes being at .3 and BananaSplits at .5 so definitely worth the trouble.
Is there currently a way to obtain bananas apart from /give? I can't find them in the store or on the fruit hill
Edit: actually I found them on the fruit hill! still don't see them in the shop...