Introduction
A 20% protein diet was used to study solids-water relationships in the feeding of cockatiel chicks (Roudybush and Grau 1983) based on similar diets used for Japanese Quail (Vohra 1972). The success of these hand—feeding trials with cockatiels permitted the present study of the protein requirements for growth of chicks from hatching to four weeks of age. Growth results were obtained from diets containing 5%to 35% protein provided by isolated soybean protein supplemented with methionine. The diets also contained 3.75% lipid and variable amounts of corn starch.
Methods
The diets were essentially the same as those used by Roudybush and Grau (1983) except that part of the regular corn starch was replaced by a modified food starch that produced a thick mixture with cold water, thus avoiding cooking. The final wet mixture was warmed to 40.5°C before feeding. The solids contents were 7% for the first three days, then 30% to the end of the trial. The composition of the 20% protein diet is given in Tables 1,2, and 3. Diets with other protein levels were identical except for isolated soybean protein, methionine, and corn starch. The ratio of methionine to protein was kept constant.
Table 1
Composition of the 20% protein diet.
Ingredient g/kg diet
Soybean oil, crude 37.5
Cellulose 50.0
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
DL-Methionine 3.5
Corn starch 575 .65
Modified food starch ***** 40.0
Total 1000.0
* See Table 2 for vitamin mixture composition
** See Table 3 for mineral mixture composition
*** Purina Protein 500K - Isolated Soy Protein. Ralston Purina Co.,
Checkerboard Square, St. Louis. MO 63164.
**** Instant Clear Jel — Food Starch — Modified. National Starch and Chemical Co.,
Bridgewater. 11.1 08807.
Table 2: Vitamin Mixture
Vitamin mg/kg diet
Vitamin B12 (1 mg/g in mannitol) 14.0
Menadione (vitamin K source) 4.9
Niacin 231.3
Riboflavin 18.7
Vitamin E (227,000 IU/lb) 238.3
Folic acid 4.7
Thiamine 9.3
Biotin 0.9
Vitamin A (30,000 IU/g) 624.0
Vitamin D3 (320,000 IU/g) 1 3.1
Pyridoxine (Vitamin B6) 18.7
Pantothenic acid (calcium salt) 75.0
Total 1252.9
Table 3
Ingredients mg/kg diet
Magnanese sulfate, MnS04•H20 297.00
Copper sulfate, CuS04•H20 97.00
Cobaltous acetate, Co(C2H302)2•4H20 20.00
Potassium iodate, KIO3 9.00
Magnesium sulfate, MgS04•7H20 3970.00
Potassium chloride. KCl 2970.00
Dibasic potassium phosphate, K2HP04 4950.00
Sodium molybdate, Na2Mo04•H2O 9.00
Sodium selenite, Na2Se03•5H20 0.66
Zinc oxide, ZnO 120.00
Ferrous sulfate, FeSO4•7H20 644 .00
Total 13086.66
Two experiments were performed. In the first the protein levels in percent of the diet were 5,10, 15, 20, and 25 with 6-13 chicks per group. In the second the protein levels were 15, 18, 20, 25, and 35% with 12-16 chicks per group.
Results
Differences in growth rates among the groups fed the various protein levels began to be apparent early and by 7 days of age the 5% and 10% protein groups were different from higher levels as shown in the growth curves of experiment 1 (figure 1). In experiment 2 (figure 2) protein levels were 15% to 35%. The two experiments were performed several weeks apart but the results were similar. The response curves of figure 3 show clear differences among the groups by 14 days, when growth was most rapid. The 15% protein level resulted in the slowest growth (P<.01), with 18% and 35% protein growing slower than 20% and 25% protein. The differences remained evident at 21 days of age, but by 35 days there were no differences among groups fed 15% or more protein.
The mortality for all groups combined was 17.3% for the first four days and 34.5% for 28 days. There were no differences among the treatments except possibly the 5% protein level group in which only one chick survived out of six.
Discussion
The difficulty of establishing the minimum dietary requirement for a nutrient is clearly shown by the data presented here. For rapid growth cockatiel chicks require 20% protein, but if eventual adult weight is used as the criterion, nutrient requirements must be set lower, possibly less than 15% protein. The time that such a lower protein diet must be fed is significantly longer, however, and thus time becomes a factor to be considered. Application of these observations to a commercial operation, whether chicks were parent-fed or hand-fed, would probably favor the higher protein level if the differences in costs of the diets were small because of the time saved to produce salable young. Feeding a marginal level of a nutrient may increase the risk of permanent stunting or susceptibility to disease or stress; however, data on this possibility are not yet available.
Cockatiel chicks tolerated a protein level of 35%, but they grew more slowly than with 20% protein.. No permanent stunting was apparent.
Summary
The protein requirement of cockatiels from hatching to 28 days of age is 20% of the diet.
- Roudybush, T.E. and C.R. Grau. 1983. Solids in diets for hand raising cockatlels. Proc. 32nd Western Poultry Disease Conference, Davis CA. Feb. 8—10, 1983. pp. 94—95.
- Vohra, P. 1972. Magnesium requirement for survival and growth of Japanese’ quail (Coturnix coturnix japonica). Poultry Sd. 51:2103—2105.
| 
