When you consider the fact that an adult pigeon will consume more food than its own mass in 20 days, you come to realize just how potent that little yolk is. Generally, I will also replace half of the water used in mixing with other types of liquids. One day I may replace half of the water with canned chicken broth which is a good source of sodium and also is good against dehydration. Another day I may use milk in place of half of the water, which is high in calcium and various vitamins. We already know that the green food is a genuine asset, so the likes of spinach, green beans, etc. is obvious.
Corn is of course a natural staple of many feeds as it is.
These additions to the normal hand feeding mixture will yield fantastic results, especially for squabs. To the hand feeding mixture we can also add vitamin supplements or even the medication you are using to fight the disease off. Additionally, if you are fighting a disease, a syringe full of plain, unflavored yogurt into the crop can help work wonders. Not only will this provide helpful bacteria, but also extra calcium, vitamins, etc. Keeping these things in mind may save your best pigeons some day.