Gracious Casport, I love the avie!
For standard birds....
you want 1/2 a cc/ml. You can put it in the beak if you are squeamish about injecting in the breast. Otherwise, in the breast, alternate sides daily. (Diabetics will know the pain of injecting in the same spot..same as with the bird) If you are going to do it orally, be sure to not SHOOT it in the beak, you an aspirate your bird.
For bantys it is 1/4 cc/ml
If you use a standard super fine insulin needle, most of them are already 1 cc or 100 units. Be sure which needles you have if you are going to use a diabetic needle. I use them super fine 100 unit (1cc) needles since the needle is the shortest and finest I have found. (That and my dad left me boxes when he passed away)
Some may not agree with this, but I will post it anyway, everyone has a right to make their own decision. If you are injecting a substantial amount of birds, it really can be a pain in the tuckus to use so many needles. Have a person help you and between injections on each bird, clean the needle with an alcohol wipe. Discard the needle than after you've done the birds, don't use it again the next day, use a fresh one.
I'd also like to note that some directions call for the tylan 50 to also be injected subcutaneously (under the skin) in the same amount that goes in the muscle or orally. I have not done this my self personally with any birds that I have had to treat for any of the multiple CRD issues that can arise. I have always just did it orally, since I am on my own when it comes to this stuff.