Increasing egg yield

As it's the depths of winter, egg yields from our hens have been minimal over the past couple of months. Yesterday however saw 9 eggs laid from our 20 birds. That's the highest since October and a good increase on the 3 - 5 we have typically had each day in recent weeks. As well as being part of our food supply, they are also currency for us, using them to exchange for other people's produce, and we also sell them for hard currency. So the more laid, the better!