I recently got rid of eight of my older hens who were two years old. Some still laid pretty good others not so good. Introduced at the same time 18 new pullets to the remainder of the flock. The remainder consisted of 22 road island reds, 11 months old. The road island reds have really slowed production down, today I only got 2 eggs. Could it be the stress of this change slowing them down? They lay pretty good throughout winter.