There are many circumstances when hand-rearing of baby birds is desirable or even essential. If a pair of birds produces more eggs than the two of them can raise or if their eggs are removed for artificial incubation, some fostering or hand-rearing arrangement is needed. These management options can be, especially useful for increasing offspring of endangered species or in rehabilitation of orphaned birds, almost all of which must be hand-reared. In our own efforts to determine nutrient requirements of cockatiel chicks, complete control of the diet and feeding was necessary; this has necessitated Hand-rearing.
The work reported here has come from studies of the cockatiel, a seed-eating altricial bird which we view as a model for many psittacines and passerines. Like other birds which are completely helpless when hatched, cockatiels depend entirely on their parents to regulate their food and water intakes. Thus they are different from precocial birds, such as domestic poultry, which are able to regulate food and water intake as soon as they hatch. This self-regulating, self-feeding nature of precocial birds has greatly reduced the difficulty of conducting nutritional studies of poultry.
While much remains to be learned about optimal methods of feeding and diets for cage birds, the formula presented in Tables 1, 2, and 3 has been found to work well with dozens of cockatiels as a control diet against which variations in protein and other nutrients have been compared. The amounts of each nutrient present in this diet can readily be calculated from composition tables, allowing the diet to be used as a reference for comparison with other diets. Some of these nutrients may exceed the bird’s minimum requirements because the quantitative requirements of cage birds are largely unknown. The diet is recommended because it has been shown to produce healthy hand-fed birds when the proportions of water and solids are properly regulated. Newly hatched chicks do well with a mixture of about 93% water and 7% solids, whereas chicks 2 or 3 days old require a less dilute diet of 70% water and 30% solids.
The composition of the mixture given in Table 1 is the solid or dry part of the diet, which is mixed with water to produce the liquid diet that is fed. To avoid confusion the ingredients are expressed as the amounts in each kilogram of solid diet, and the amount of this solid diet and water to be mixed is indicated separately. For example, the diet designated as a 20% protein diet (200g crude protein per kg) is fed at 7% solids (7g solid diet plus 93g water) for the first 2 or 3 days after hatching. Then the diet is changed to 30% solids (30g solid diet plus 70g water) until weaning, some 6 to 8 weeks later. Weighing the components is important because of the unreliability of measuring volumes of dry substances. The viscosity, or thickness, of the final diet may be controlled by altering the amount of modified starch. Viscosity should not be adjusted by changing the proportions of water and solids. Viscosity is not a reliable measure of water content.
In formulating the diet we have aimed at providing all the nutrients except protein at or above the levels known to be required by young turkey poults (National Research Council 1977, [1984 edition now available]). Turkeys were selected because they have the highest known requirements among the various poultry species. The amount of protein is based on experiments with cockatiels (Roudybush and Grau, unpublished). The ingredients we use are widely available. The powdered cornstarch is a commercial product. The isolated soybean protein is a type used a meat extender, and contains about 1% sodium. Crude soybean oil is preferred over the refined vegetable oil because in addition to triglycerides containing polyunsaturated fatty acids it contains natural antioxidants plus small amounts of phosphatides and plant sterols. We have not yet studied possible results of omitting cellulose, a type of fiber, or of trying different levels of this inert substance. Methionine is added to supplement the soybean protein, which is a poor source of this sulfur amino acid. The vitamin and mineral mixtures are made in bulk and may be stored for months. Vitamins are kept in refrigerated storage. The solid diet mixture is also stored under refrigeration. All ingredients are finely powdered so that a syringe can be used to feed the final water- containing mixture.
In preparation for feeding, the amount of solid feed needed for a single feeding period is weighed into a beaker, the calculated weight of warm water is added, they are mixed, taken up in a sterile, disposable syringe, and fed at a temperature of 40.5°C (105°F). Any mixed food not used at that feeding is discarded to avoid any possibility of spoilage. New syringes are used for each feeding period.
Techniques of feeding, schedules, and data recording will vary from one aviculturist to another and the methods described here are subject to modification. Chicks are fed as soon after hatching as possible, certainly within 8 hours, and preferably earlier. A 1 ml syringe is placed against the side of the chick’s beak. The plunger is gently depressed so the chick is allowed to swallow as much as it likes. No tube or needle is attached to the syringe. This dilute-formula feeding is repeated at least every two hours from 6 a.m. to 10 p.m. The schedule is 7% solids for 48 to 72 hours, then 30% solids less often, until weaning. By 48 hours after hatching the crop has expanded and more food can be given by gently forcing it into the crop using the syringe. By 72 hours post-hatching feeding is best done quickly, with the operator holding the chick by the head so that the esophagus (gullet) is straight from mouth to crop. At each feeding the amount given is enough to fill the crop sufficiently to prevent its becoming totally empty before the next feeding, except overnight between the 10 p.m. and 6 a.m. feedings.
As part of the experimental program chicks were weighed daily before the first feeding at 6 a.m., using a digital-reading, five-second integrating, electronic balance. An example of a growth curve obtained is presented in the figure. Food intake data are easily obtained by weighing the chick before and after each feeding. Because the diet fill is large in relation to the empty body weight, it is difficult to compare growth of hand-reared and parent- reared chicks. Parents feed frequently, even at night, when chicks are young, so their chicks are never empty. In one comparison of parent-fed and hand-fed chicks, body weights for growing chicks were slightly higher in parent-fed chicks but at weaning time at 6 to 8 weeks there were no differences (Nearenberg and Roudybush, unpublished). In this study the parents were feeding the corn and isolated soybean protein diet described in this issue of the Exotic Bird Report (see below).
A question has often been raised about the application of research done on cockatiels to other seed-eating birds. No general answer can be given, so tests need to be extended to a variety of species. The diet presented in Table 1 has not been tested extensively except with cockatiels, but successful small-scale tests of seed eaters have been carried out by Juanita Heineman and Joyce Long of the Peninsula SPCA, Wildlife Department. Others have used this diet to raise several large psittacines after an initial period of parent rearing. It is hoped that future tests will be carried out in 1985 at various breeding establishments and rehabilitation centers.
Finally, it is unlikely that many breeders would choose cockatiels for a hand-rearing operation because of their low market value. However, a case can now be made for hand-feeding cockatiels for the pet trade, because efficiencies of handling and quality of diets permit rearing as many as 300 chicks by a single operator, if the chicks are of the same age and if the feeder is willing to feed every two hours for 18 hours per day for the first three days, then less often for 6 to 8 weeks.
Reference: National Research Council, 1977, Nutrient Requirements of Poultry, Seventh Revised Edition, National Academy of Sciences, Washington, D.C. (Eighth Revised Edition, 1984).
Ingredient g/kg diet
Soybean oil, crude 37.5
Calcium carbonate, CaCO3 10.0
Dicalcium phosphate, CaHPO4•2H2O 30.0
Vitamin mixture * 1.25
Mineral mixture ** 13.1
Choline chloride (60%) 4.2
Isolated soybean protein (87% protein)*** 234.8
Corn starch 575.65
Modified food starch **** 40.0
* See Table 2 for vitamin mixture composition
** See Table 3 for mineral mixture composition
*** Purina Protein 500E - Isolated Soy Protein. Checkerboard Square, St. Louis, MO 63164.
****Instant Clear Jel - Food Starch - Modified. Chemical Co., Bridgewater, NJ 08807.
Table 2: Vitamin Mixture Table 3: Mineral Mixture
Vitamin mg/kg diet Ingredients mg/kg diet
Vitamin B12 (1 mg/g in mannitol) 14.0 Magnanese sulfate, MnSO4•H2O 297.00
Menadione (vitamin K source) 4.9 Copper sulfate, CuSO4•H2O 97.00
Niacin 231.3 Cobaltous acetate, Co(C2H302)2•4H20 20.00
Riboflavin 18.7 Potassium iodate, KI03 9.00
Vitamin E (227,000 IU/lb) 238.3 Magnesium sulfate, MgSO4•7H20 3970.00
Folic acid 4.7 Potassium chloride, KC1 2970.00
Thiamine 9.3 Dibasic potassium phosphate, K2HPO4 4950.00
Biotin 0.9 Sodium rnolybdate, Na2MoO4•2H2O 9.00
Vitamin A (30,000 IU/g) 624.0 Sodium selenite, Na2SeO3•5H2O 0.66
Vitamin D3 (320,000 IU/g) 13.1 Zinc oxide, ZnO 120.00
Pyridoxine (Vitamin B6) 18.7 Ferrous sulfate, FeSO4•7H2O 644.00
Pantothenic acid (calcium salt) 75.0 Total 13086.66