Abstract
Aviculrurists differ about the composition of the best diet for handrearing psittacine chicks; however, most would agree that an ideal mixture would duplicate the composition of the food that successful parents provide for their chicks. Unfortunately, information about the food that chicks normally receive has proved to be virtually impossible to collect. It is difficult to obtain a representative sample of crop contents because food passage is rapid and the solid and liquid portions may not leave the crop at the same time.
An experimental approach to determine the optimum diet for hand-rearing depends upon formulation of a nutritious dry diet, feeding mixtures of the food with amounts of water, and observing the effects on growth and survival of cockatiel chicks from hatching until they are able ro feed themselves. We used this approach to determine the best mixture of dry food and water with the aid of a grant from the American Federation of Aviculture through its Research Committee. This research may also serve as a guide to solving problems of hand-rearing of other psirtacine birds.
METHODS
Cockariel eggs from the Avian Sciences breeding flock were incubated artificially and within a few hours after hatching were placed in a Brower incubator where they were brooded throughout the experiments at a temperature of35 °C (95° F). Each chick was kept in its own paper bag (size number 2), with autoclaved shavings in the bottom to absorb droppings. Feeding was clone with sterile, disposable, plastic syringes without tubing or needle, starting with the I ml. size. For larger chicks, the 12 ml. size was used.
The dry diet, which was mixed with varying proportions of distilled water, contained 20% protein from a highprotein, isolated soybean protein powder, 60.5% corn starch, 3.75% crude soybean oil, 5% cellulose, 0.4% DL-methionine, and sources of purified vitamins and minerals. The dry diet and water to provide the desired proportions of solids were mixed thoroughly and heated in a microwave oven to coagulate the starch and prevent separation ofliquid and solids. Occasional stirring avoided lumpiness or local overheating. Diets containing more than 10% solids were prepared by coagulating a portion of the diet, adding the correct amount of water, and then enough dry diet to achieve the final mixture. These manipulations were necessary to obtain a consistency similar to thick yogurt so that diets could easily be extruded from the syringe.
Chicks were fed the diets, heated to 37.5°C (100°F), at intervals that depended on the age of the bird and the solids in the diet. Except for the period between 10 PM and 6 AM, crops were not allowed to be empty. An approximate schedule of feeding was nine feedings per day for days 1-4, five feedings for days 5-15, four feedings for days 16-24, 3 feedings for days 25-36. The shortest interval between feedings was two hours. Each chick was weighed daily before the first feeding at 6 AM.
Four experiments were performed using a total of 108 chicks in 16 groups. The solids contents of the diets were varied from 5% to 50% solids. Two groups were fed 10% solids for four days, then either 30% or 50% solids for the remainder of the experiment. Another two groups were fed 7 % solids for three days, then 30% solids to five weeks of age. All other chicks were fed their particular diets from hatching to the conclusion of the experiment.
The principal criteria used to evaluate the diets were growth and survival. Growth could be followed throughout an experiment, whereas survival yielded only the age at which death occured. Observations were also made on behaviour and feathering.
RESULTS
It is usually true when exploratory studies such as...