Abstract
Concepts in Formulating a Diet
We asked the Research Committee of the American Federation of Aviculture if they were interested in supporting a research project with budgerigars (Melopsittacus undulatus). They were very interested in our proposed project to determine the protein requirements and utilization of dietary ingredients in a balanced diet based on other than seeds, which have been the basic dietary ingredients that most bird owners feed. The proposal was the research requirements for a Masters Degree in Avian Nutrition at the Department of Animal Science, Michigan State University by Mr. Michael Underwood. This report will summarize some of the interesting findings in that research endeavor.
As we pointed out to the AFA committee, seed mixes are most often deficient in vitamins, minerals, and certain essential amino acids. Furthermore, the birds dehull the seeds, thereby tossing away fiber, an important part of the diet and B vitamins that reside in the seed hull. These are items that the bird owner must supplement in the diet if they expect to approach a balanced nutrition. One other important aspect of seeds is that those with high protein concentrations are usually the ones with high fat content so that, when consumed as the major part of the diet, they result in fatty kidneys, livers and an accumulation of fat in blood vessels, deposits that often result in obesity and damage to those important· organs. Exotic birds in captivity just do not live as long as they should; everyone recognizes this and the lack of proper nutrition has been a major cause for this premature mortality. A need for better diets is obvious. We had thought of formulating a diet from seeds but, with the birds throwing away the hulls, an undetermined quantity of the diet, we gave up on that idea. We just could not see us sitting down with a pile of seeds, taking each hull off the seed and doing enough of these to obtain an exact weighing of what proportion the hulls weight for each type of seed. Then the other problem was how do you add the proper concentrations of vitamins, minerals, and essential amino acids to the diet and be certain that the correct proportion of all nutrients are consumed by each bird. We are very aware of attempts to coat seed hulls with vitamins but penetration of the hulls is impossible to accomplish. Remember, the hull is nature's way of protecting the germ inside that seed. There is no scientific evidence to show that such coatings with vitamins penetrate. Then you are back to the problem of the hull being discarded. So, our research was the first to try and develop a diet for budgies from ingredients most popularly used in pet foods for dogs, cats, fish, quail and pigeons. Pelleting would have been the ideal approach to the diet. But, because very small amounts were to be made for each experiment, we decided to chance the feeding of the diet as a mixture of the ingredients as they are purchased from the mills.
We had to make certain assumptions to study the requirement for protein and assume certain detailed considerations for the need of the ten essential amino acids that most birds are known to require. This is unlike mammals that only require the ten essential amino acids during their early growth. After that, the requirements shift to a lesser number of amino acids and it depends on the species as to which amino acid is no longer required. That is one reason why feeding cat, dog, monkey, or rodent chow to birds is a no-no.
Long term feeding problems from improper nutrition do occur. We also had to assume that mineral and vitamin requirements would be similar to that of certain animals including other birds. We used our knowledge from the research that has been performed with farm animals to derive a diet that would be optimum in all respects except for the particular nutritional item that we desired to vary and, in this case, that was the protein concentration. In addition, we had to assume certain energy requirements. As a result of changing only the protein and maintaining the energy concentration constant we had wide shifts in the protein to energy ratio, a very important consideration when formulating diets. This is of utmost importance as the energy concentration of the diet is a major determinant for controlling food intake. This meant that in the future we would have to research the protein energy ratios that are optimum for the budgie. Another consideration was the make-up of the calories that are part of the energy constituency. These are very important because of feedback mechanisms that control how the liver functions for regulating fat metabolism. With all of these as unknowns for budgies, one would suspect that it would be difficult to arrive at a diet that would work. Actually, with sufficient nutritional knowledge gained from other animals, the formulation of such a diet is not difficult for a professional nutritionist knowledgeable in the area of bioenergetics to arrive at what would be a close approximation of what the budgie requires. In some situations, we could provide an excess to be certain that the nutrient would be available yet know that no harm would come to the animal. Certain nutrients have a wide margin of safety so they could be present in excess, but one has to be careful not to overdo this as nutrient interaction can make other nutrients unavailable. There is basic nutritional information applicable to most animals that would allow some very good guesses on what the budgies would require nutritionally. What we wanted to do was to establish with better certainty what those requirements actually were. One must also remember that environmental conditions will influence dietary considerations so we had to make certain assumptions in regard to what these would be. That part was easy because we controlled the environment to a considerable extent.
The diets that we decided to use were varied in the following protein concentrations: 12 % , 17 % , 22 % and 27%. For comparison, we included in the experiment a seed-type diet that was indicated to be used for feeding budgies that we purchased at a local store. It contained 11 % crude protein.