Avian Nutrition:
Formulated Diets in Avian Nutrition

Formulated diets for psittacines consist of pellets, extruded foods, and whole grains and/or seeds with pelleted material added to balance the entire product such as Nutri-Berries® and Avi-Cakes®. There are some seed-based foods where a pellet is added to balance the seed mixture or a vitamin/mineral mix that is coated on the outside of the seed. All of these products may be considered "balanced" from a nutritional point of view. From a label perspective, the nutritional balance is not stated but implied as most of these diets represent variations of a balanced diet for galliforms or a diet prepared according to Association of Avian Veterinarians (AAV) panel recommendations. This is because there are few nutritional studies on maintenance requirement for this large group of psittacine species with diverse ecological niches. This is compounded by the need to better understand the nutritional requirements of life stages of a particular species.

Pellets

Pellets are made by grinding a variety of grains based on the manufacturer’s recommendations and adding vitamins and minerals to make the final product balanced. Grinding reduces particle size to make it easier to produce a homogenous mixture. This process is used so that the bird is unable to pick out and eat the components of the food that it likes. By grinding and mixing the food, it ensures that the bird receives this balanced diet. Once ground, the mix is commonly put through a hammer mill to ensure appropriate particle size. Liquids may then be added and the ground mix pelleted. Pelleting uses a dry or steam process under heat (70-80°C) whereby the mix is heated and forced through holes in a die using a roller. As it emerges as cylindrical particles of a constant diameter, a turning knife cuts the pellets as preset lengths.

Extruded diets1

Most of the "pellets" that are available today are really extruded diets. These diets are made by mixing ground grains with the vitamin and mineral components that will balance the final formula. This mix is then forced through an extruder, which may involve a dry process or a steam process using and injection technique. The mixture is then forced under pressure and temperature between 90-180°C through the extruder with a dwell time between 30 seconds to several minutes. Moisture added as steam may be between 0 and 20%. The holes in the plate of the extruder determine the shape of the food pieces. The pressure helps maintain the water in a liquid state. The rapid expansion on leaving the extruder causes instantaneous evaporation of intracellular water, rupturing the plant cells. The food produced is partially hydrolyzed but the cooking can kill infectous agents if present.

Lafeber Products

Nutri-Berries® and Avi-Cakes® use whole grains and seeds that are mixed with a pellet that balances the product before it is stuck together. It is similar to a pellet except that it is not ground. Seed Mixtures Other seed products put a pellet into the mixture to balance the entire product. This would require that the bird eat those pellets along with the seed to receive a balanced meal. Some of these products coat the seeds with vitamins and minerals to balance the entire product. The coatings are often colored and are applied to the seed hull; however, the vitamin and mineral intake from the coatings is markedly reduced if the bird dehulls the seeds.