Raptors in the wild rarely eat the whole of the prey that they catch. They often eat the nutritious bits (liver etc.) and leave the rest for the carrion eaters. This makes our falconry birds quite vulnerable to inadequate diets. Whilst this logic does not apply in the same way to owls, the use of "convenience" foods certainly causes plenty of nutritional problems even in those birds that swallow their prey whole. The food we feed to our birds can only be as nutritious as the food the animal was eating in the days leading up to its death and you probably have no control or knowledge of that. Day old chicks are a case in point. They have spent a few weeks with practically no nutritional input at all. We think of them as exhausted eggs!
Additionally, captive birds use less energy than their wild counterparts so we feed them less. This means they get fewer key nutrients and they can become deficient in vitamins, minerals (particularly calcium) and amino acids (critical for feather growth and quality). The simple answer to this dilemma is to add a well-formulated supplement to your birds' diet. Experience tells us that supplemented birds moult better, breed better and even fly more safely and effectively than birds fed on small animal/bird diets alone.
If you have never used a supplement before you may be thinking that it just adds a major chore. In fact it is quite simple to bare the breast of the food (or rip the skin open if you wish) and dunk the exposed area into the powder. Our new Raptor Essentialsis designed to stick very well to exposed skin. Very dry frozen food may require just a tiny bit of moistening. As the dose rate is proportional to the amount of food consumed, you simply dip each carcass into the correct amount of supplement. For very highly-strung birds like Goshawks, every other carcass may suffice.
Once you have fed the supplement to your bird, the product starts to work for you. The biggest challenge is to ensure that its nutrients actually cross the gut wall and enter the bloodstream, so that the blood can then deliver the nutrients to wherever in the body they are needed. The most modern supplements do their best to mimic the natural form of nutrients, which enormously enhances the absorption rate and bio-availability. This produces significant benefits for both your birds and your pocket. In particular you use less of the supplement for the same effect!