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Formulated Diets Versus Seed Mixtures for Psittacines Nutrition of Caged BirdsFormulated Diets Versus Seed Mixtures for Psittacines1,2DUANE E. ULLREY3, MARY E. ALLEN4 AND DAVID J. BAER5 Comparative Nutrition Group, Department of Animal Science, Michigan State University, East Lansing, MI Abstract-Psittacines are often classified as seed eaters despite studies that have established great diversity in food habits in the wild. While seeds are consumed, so are flowers, buds, leaves, fruits and cambium. Some psittacines consume parts of >80 species of grasses, forbs, shrubs and trees. In addition, insects may be important. Although there are few controlled studies of the requirements of psittacines, it is probable that most nutrient needs are comparable to those of domesticated precocial birds that have been thoroughly studied. Commercial seed mixes for psittacines commonly contain corn, sunflower, safflower, pumpkin and squash seeds, wheat, peanuts, millet, oat groats and buckwheat, although other seeds may be present. Because hulls/shells comprise 18-69% of these seeds and they are removed before swallowing, a significant proportion of typical seed mixtures is waste. Some of the seeds also are very high in fat and promote obesity. Common nutrient deficiencies of decorticated seeds include lysine, calcium, available phosphorus, sodium, manganese, zinc, iron, iodine, selenium, vitamins A, D, E and K, riboflavin, pantothenic acid, available niacin, vitamin B-12 and choline. Attempts to correct these deficiencies by incorporating pellets into seed mixes are usually thwarted by rejection of the pellets and disproportionate consumption of items that are more highly favored. An extruded diet formulated to meet the projected nutrient needs of psittacines was fed with fruits and vegetables to eight species of psittacines was fed with fruits and vegetables to eight species of psittacines for the 66% observed during the previous 2 y when these psittacines were fed seeds, fruits and vegetables. Although this extruded diet was well accepted in a mixture of fruits and vegetables and met nutrient needs, analyses have shown that not all commercial formulated diets are of equal merit. J. Nutr. 121: S193-S205, 1991. Indexing Key Words:· symposium · birds · psittacines · seed · composition · nutrient · requirements · formulated diet · gout Aviculturists often classify caged birds on the basis of their apparent food preferences in captivity (1). The Psittacidae comprise a family of birds with stout, hooked bills commonly called seed eaters despite field studies (2-5) establishing great diversity in food habits in the wild. Psittacines are widespread in tropical and south temperate areas of the world, with major populations in the neotropics and Australia. These regions vary widely in rainfall and temperature and in the food plants that the environment will support (6). Since indigenous psittacines coevolved with their food supply, their food choices in an undegraded habitat represent a nutritional wisdom built on generations of experience. However, studies of caged psittacines suggest that the nutritional wisdom of wild birds does not transfer to captive birds offered cultivated seeds as their principal food. In fact, specific instances of failed dietary husbandry based on seed mixtures have led to this review of natural dietary habits of certain psittacines, the nutritional limitations of seeds and the development of diets formulated to be nutritionally complete. FOOD SELECTION BY CERTAIN WI LD PSITTACINESBiologists with significant field experience will testify how difficult it is to gather quantitative food intake data on free-living birds. Even qualitative information is difficult to gather. Nevertheless, the following reports illustrate the diversity of food choices in the wild and the opportunity such diversity provides for meeting nutrient needs. Cannon (4), in a study of the diets of Eastern (Platycercus eximius) and Pale-headed (P. adscitus) Rosellas in Queensland, Australia, spent over 200 h in each of two study areas observing food consumption by these two species throughout the year. Both study areas had been modified from their primitive state by agricultural practices, including cultivation of alfalfa (Medicago sativa), milo or grain sorghum (Sorghum bicolor) and oats (Avena sativa). Some regions were pastured, and seeds in dung were consumed. Food plants used by Eastern and Pale-headed Rosellas included grasses, forbs, shrubs and trees, and these psittacines fed on 82 and 47 plant species, respectively. Both rosellas fed mainly on fruits and seeds and to a lesser extent on flowers. In addition, significant intakes of insects were noted, particularly during July when coccids and psyllids attached to Eucalyptus leaves constituted nearly 50% of the diet of the Eastern Rosella. Saunders (2) studied the food habits of the short-billed form of the White-tailed Black Cockatoo (Calyptorhynchus funereus) in two areas of Western Australia. The clearing of woodlands had degraded the habitat to some extent, and in one study area, parent birds were forced to forage over long distances to find adequate food for their nestlings. Because this effort was only partly successful, growth rates of the young, fledging weights and breeding success were lower than in the area where large amounts of native vegetation were available close to nest sites. A total of 30 plant species was exploited in the two nesting areas, with flowers and seeds being the main parts eaten. Some plant species were para sitized by insects whose larvae developed in the flowers or stems. Larvae from the families Cerambycidae and Pyralidae were identified in the crops of nestlings in sufficient numbers to suggest deliberate collection. The nonbreeding season was characterized by some change in food plants, partly as a consequence of seasonal environmental change and partly due to migration to areas of improved food availability. The two populations o cockatoos fed on a total of over 30 species of plants during the nonbreeding season. The seeds of pine species were particularly important to one population. Insect larvae were also consumed. Wyndham (3) studied the food habits of the budgerigar (Melopsittacus undulatus) in inland mideastem Australia. This region is characterized by open or lightly timbered plains and a few remnant mountain ranges. It is semiarid to arid, east to west, and rain falls primarily in the summer in the north and in the winter in the south. Seeds from 21 to 39 species of ground plants were eaten depending upon area. No plant food from upper vegetational strata and no insects were identified in crop con- tents. The seeds eaten had a mean length from 0.5 (Eragrostis spp.) to 2.5 mm (Astrebla squarrosa). Most seeds were intermediate in this range and weighed (with husk) from 0.36 to 1.33 mg. The seeds were normally husked before being swallowed. Diet choices appeared to be governed largely by availability. Snyder et al. (5), in a broad study of the biology of the Bahama Parrot (Amazona leucocephala bahamensis), presented some observations on its food habits. This species was first cited as endangered in 1966 (7). A small population lives on the low limestone island of Abaco, the second largest of the Bahamian Islands. A second population lives on the island of Great Inagua. Abaco's climate is subtropical with an average rainfall of 154 cm. Monthly temperature means range from 21 to 27 degrees celsius. The geology of Great Inagna is similar to that of Abaco, but it is much drier, with a mean annual rainfall of 70 cm. Monthly mean temperatures range from 24 to 29 degrees celsius. Bahama Parrots were observed feeding on 16 plant species. They were catholic in their tastes and ate the inner portions of green, unopened Pinus caribaea cones, stems of woe vine (Cassytha filiformis), fruits of wild dilly (Manilkara bahamensis), cinnecord (Acacia choriophylla), poisonwood (Metopium toxiferum) and naked wood (Myrcianthes fragrans), and the fruit and inner bark (cambium) of Caribbean pine. They also fed on the fruit or seeds of wild tamarind (Lysiloma latisiliquum), jumbay (Leucaena leucocephala), sea grape (Coccoloba uvifera), buttonwood (Conocarpus erectus), buffalo top palm (Thrinax morrisii), silver top palm (Coccothrinax argentata), Tabebuia bahamensis, Bursera simaruba, Swietenia mahagoni and Sabal palmetto. It is apparent that, except for millet (Panicum milioides), which may be eaten by wild budgerigars in agricultural areas, most seeds found in mixtures sold for caged psittacines are foreign to the experience of their free-living relatives. Since this is true, it is appropriate to compare the nutrient composition of these cultured seeds with the nutrient requirements of the birds to which they are fed. By this means one can identify potential deficiency problems and develop a strategy to correct them. NUTRIENT REQUIREMENTS Most of the information we have on quantitative nutrient requirements of birds has been obtained from studies of precocial species. Much of this information has been summarized in the National Academy of Sciences/National Research Council (NRC) publication on Nutrient Requirements of Poultry (8). Nutrient requirements presented in this document are defined as established values, based on research data, or estimated values, where experimental evidence is less than complete. The NRC nutrient requirements for growth of seven precocial species have been recalculated and presented in Table 1. Table 1 Nutrient requirements for growth of precocial birds1
1 Recalculated from Nutrient Requirements of Poultry (8) and expressed on a dietary dry matter basis. Values derived from requirements for the following periods after hatching: chickens, 0-3 wk; turkeys, 0-4 wk; geese, 0-6 wk; ducks, 0-2 wk; pheasants, starting; bobwhite quail, starting; Japanese quail, starting and growing. ME concentrations (J/kg dry matter) of diets to which these requirements apply are chickens, 14.88; turkeys, 13.02; geese, 13.48, ducks, 13.48; pheasants, 13.02; bobwhite quail 13.02; Japanese quail, 13.95. 2 Meat type. 3 Commercial feed ingredients of plant origin have 60 to 70% of their phosphorus bound in phytin. Utilization of phytin phosphorus by young or adult poultry is considered negligible. The recalculation was made to convert the NRC requirements, expressed in diets as fed, to a dry matter basis. This was done by dividing the NRC values by 0.9, assuming that feedstuffs used in poultry diets contain an average of 90% dry matter. Similar recalculations were made for NRC nutrient requirements for breeding birds, and these recalculated values are presented in Table 2. Table 2 Nutrient requirements for breeding of precocial birds1
1 Recalculated from nutrient Requirements of Poultry (8) and expressed on a dietary dry matter basis. ME concentrations (J/kg DM) of diets to which these requirements apply are chickens, 13.25; turkeys, 13.48; geese, 13.48; ducks, 13.48; pheasants, 13.25; bobwhite quail, 13.25; Japanese quail, 13.95. 2 Meat type, except values in parentheses are for Leghorn type. 3 Commercial feed ingredients of plant origin have 60 to 70% of their phosphorus bound in phytin. Utilization of phytin phosphorus by young or adult poulty is considered negligible. Only those nutrients that are expected to be of practical importance in diets containing natural feedstuffs are listed. It should be noted that the NRC nutrient requirements do not include a margin of safety to account for variations in nutrient concentration or availability in feed ingredients or for nutrient losses during diet processing and storage.Controlled research on nutrient requirements of altricial birds is very limited. Roudybush and Grau (9) studied the protein requirement of hand-fed cockatiel (Nymphicus hollandicus) chicks, using purified diets containing various proportions of isolated soybean protein and crystalline DL-methionine. When the effects of diets containing 5, 10, 15, 18, 20, 25 or 35% protein upon weight gain and mortality were examined from 4 to 28 d after hatching, these workers concluded that 20% protein was the lowest concentration permitting maximal growth. When Grau and Roudybush (10) fed a purified diet supplying amino acids in crystalline form (20% protein equivalent) and studied the effects of lysine concentrations of 0.2, 0.4, 0.6, 0.8 and 1.2% upon weight gain and mortality in cockatiels from 4 to 28 d after hatching, they concluded that 0.8% lysine was the minimum requirement. It may be significant that body weights of cockatiel chicks at 14 and 28 d were about twice as great when chicks were fed a control diet containing 20% protein from isolated soybean protein as compared with chicks fed the crystalline amino acid diet with 0.80% lysine. While these data are inadequate from which to generalize, they provide no clear evidence that dietary protein and lysine requirements of growing psittacines deviate appreciably from the needs of growing precocial birds about which we know so much. Based on data on cockatiels (9), seven species of macaws, nine species of cockatoos, two species of parrots and six species of amazons (11), psittacine chicks that are hand-fed appropriate diets will gain weight even faster than meat-type chickens for several weeks after hatching. To support these rapid rates of gain and normal body composition, it seems reasonable that the nutrient densities of diets fed to growing psittacines should be at least as great as those found necessary for slower growing precocial birds. NUTRIENT COMPOSITION OF SEEDSCommercial seed mixtures for psittacines commonly contain corn, sunflower, safflower, pumpkin and squash seeds, wheat, peanuts, millet, oat groats and buckwheat. Other seeds that may be present include milo, rice, niger, hemp, canary grass, rape, flax, sesame, anise, fennel, lettuce, false flax, poppy, pea, caraway and teazle. Some psittacines are also fed Brazilnuts, English walnuts, cashew nuts, hazelnuts, almonds, macadamia nuts, pistachio nuts, beechnuts, pinyon nuts and pecans. The common and scientific names of these seeds are presented in Table 3. Table 3 Common and scientifc names of seeds to psittacines
The proportions of seeds in five commercial products sold in the United States are shown in Table 4.
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