Why did my hens stop laying all of a sudden?

I had two separate flocks, one flock had 8 hens and a roo, the other 9 hens and a roo. I purchased 4 more hens and kept them separate for 2 weeks. At that time I was getting a total of 12-13 eggs a day from a total of 21 hens using an early morning light to keep egg production up in the winter.

One nice sunny day, I let all the chickens out to free roam together. The two roos went to battle and there was a clear winner. This fight didn't seem to bother the hens at all. Since that day they have all been cooped in one large area and let free roam when I have days at home to watch for predators, etc. At the same time I was given a sack of cracked corn which I added to their usual layer pellets. Then the weather turned from mid 50's high to mid 20-30's. In a one week period I went from getting 12-13 eggs a day to only 2-3 a day and that has continued for 3 weeks now. The weather has stayed in the 20-30's.
I have stopped feeding them the cracked corn for now. The light comes on at 4:30 am and goes off at 8:00 am (as usual). The alpha roo keeps the other roo in check with a chase and a few pecks every day which the second roo is submissive to alpha. All the hens seem happy, fresh water, lots of layer pellets. They have a hen house to roost in when it gets cold but most of them continue to sleep out in the run on a roost.


Most people say the cold weather shouldn't affect their laying. The majority of the eggs I'm getting are from the last 4 hens I bought. I know the first 8 hens are varying ages. I hatched and raised some of them and some I bought. The next 9 were a flock of delawares I bought several months ago that were proficient layers up to this point. It was their roo that got second place in the alpha battle.

What happened? What do I do to get my production back up?