Her beak has been pale lately compared to my other pekins then it started to develop dark spots and now you can see the flesh underneath. She seems to be energetic and acting okay but is smaller than the other females. Any ideas what could be wrong or what I can do for her? She's about 4 months old. I'm afraid it could be malnutrition due to treating them with lettuce too much? The others all look fine. Please help!
It has a range of vitamins and minerals, though it is mainly water, and it does have fewer nutrients than lettuces or greens with darker leaves. But as long as ducks have access to a quality food, having some daily lettuce is not a problem. It's certainly better than something like bread because it will not fill them up (being mainly water) and so they will still go in search of their proper food after the lettuce quickly goes through their system.