This will in turn destroy Red Blood Cells. Anemia, Jaundice, Bloody Urine. Be cautious if feeding cooked onion in small amounts. Apple Seeds contain Cyanide. Be sure to always remove apple seeds before giving a portion to your birds.
Mushrooms have the potential of being toxic.
Dairy items are not digested in birds. Birds do not have the digestive enzymes necessary to process milk. There are some products that are available on the market as an alternative to dairy products. Soy Milk, Tofu Cheese, etc. Which can be given to your birds as an alternative to dairy items.