It’s great that your chicken is still laying every day and not broody! If she hasn't grown back any feathers on her chest after molting, it could be a couple of things. Here are some possible causes:
- Feather Pecking: Sometimes, chickens will peck at each other, especially in the chest area, and it can lead to missing feathers. Even if you don't see aggressive behavior, subtle pecking can cause this. It's worth observing her closely, especially when they're interacting with each other.
- Nutritional Deficiencies: Molting can put a strain on a chicken’s body, and if she’s not getting enough protein or essential nutrients, it might delay feather regrowth. Make sure her diet includes enough protein and calcium, and consider adding a higher-protein supplement during molting.
- Hormonal Imbalance: If her molt was irregular or the chest feathers aren’t growing back, it might be a hormonal issue. This is less common but worth considering.
- Health Issues: While you've not noticed mites, other parasites or skin infections could be at play. Sometimes chickens will have issues that aren’t immediately obvious, so a closer inspection of the skin or a fecal test by a vet could help rule out any health problems.
If none of your other chickens are showing similar issues and she's otherwise healthy, I would suggest continuing to monitor her. If her feather loss doesn't improve in a few weeks or if you notice any changes in behavior or laying, it might be worth consulting a vet.
Have you noticed any other signs like changes in behavior, appetite, or skin irritation?