M.F.
don't worry about it too much L.,
my kids are the same way they are 7, 10 & 12.
besides all meats provide the exact same amino acids that your child needs to grow (weather its chicken, beef fish, or pork.) only the fat content is concerning to me
Also, you need to understand children between 6 and 11 years old only need 2 ounces of protien at lunch time and again at supper time.
Eggs, beans and legumes also provide protien
hope this helps