The nutrient requirements of newly hatched psittacines and other altricial birds are unknown, but having such information would be useful in improving total breeding productivity of cage birds and of endangered and vulnerable species. The present studies, part of a project designed to quantify the nutritional needs of cockatiels, were limited to protein and water requirements. In the course of this work, unexpected mortality of young birds that had been growing well led to consideration of the microbial populations which share the chick’s alimentary environment. This report is an attempt to identify some of the reasons for the difficulties observed in hand-rearing cockatiel chicks.
Materials and Methods
Eggs obtained from the flock of cockatiels maintained by the Department of Avian Sciences were collected daily, stored at 3.3°C (56°F) and incubated at 37.5°C
(99.5°F) dry bulb and 29.4 - 30.0°C (85-86°F) wet bulb. Incubation was started in two groups ten days apart. No eggs were stored longer than ten days. Five eggs hatched from the first group and twelve from the second. Chicks were weighed before and after each feeding. Feeding was done with sterile, disposable, plastic syringes every two hours from 6:00 A.M. to 10:00 P.M..
Chicks were brooded in a Brower incubator maintained at 35°C (95°F) throughout
the experiment. Each chick was kept in the incubator in an individual No. 2 paper bag with shavings in the bottom to absorb feces.
*Vitamin premix provided per Kg diet: 19,394
Soybean oil 37.5 IU Vitamin A, 4,363 IU Vitamin D3, 121 IU
Cellulose 50.0 Vitamin E, 4.85 mg Menadione, 14 ug B12,
CaCO3 10.0 9.70 mg Thiamin, 242.4 mg Niacin,
CaHPO4•2H20 30.0 19.4 mg Riboflavin, 19.4 mg Pyridoxine,
NaC1 9.9 77.6 mg Pantothenic Acid, 4.85 mg Folic Acid
Choline Chloride (60%) 4.2 1.0 mg Biotin.
Corn Starch 605.1 **Mineral premix provided per kg diet:
Vitamin Premix* 1.0 297 mg MnSO4•H2O, 97 mg CuSO4•5H2O,
Mineral Premix** 13.1 20 mg Co Acetate•4H20, 9 mg KIO, 3970 mg
760.8 MgSO4•7H2O, 2970 mg KC1, 4950 mg
K2HPO4, 9 mg Na2 Mo04•2H20,
0.66 mg Na Selenite, 120 mg ZnO, 644 mg
Diet (Constituents in g/kg)
Ingredient 0% Protein 8% Protein 12% Protein 20% Protein
Basal Diet 760.8 760.8 760.8 760.8
Starch 239.2 143.5 95.6 0
Isolated Soy 0 94.1 141.2 235.2
Methionine 0 1.6 2.4 4.0
Total 1000.0 1000.0 1000.0 1000.0
The diets used are shown in Table 1. The chicks from the first hatch were divided into 2 groups. One group of 3 chicks was fed a mixture composed of 1 part by weight of 20% protein dry diet plus 14 parts of distilled water (6.7% dry diet). The remaining 2 chicks were fed a mixture of 1 part 20% protein dry diet plus 19 parts of distilled water (5% dry diet). The dry diets were refrigerated until diluted and mixed, heated to boiling in a microwave oven to coagulate the diet, and refrigerated until fed. Diets were heated to 37.8 C (100 F) in a microwave oven before feeding.
The second hatch of chicks was given the 20% protein dry diet, fed at 6.7% dry matter, for one week. They were then divided into four groups which were fed 0, 8, 12 or 20% protein diets (dry basis) diluted with water to 6.7% dry matter.
For the microbiological studies crop contents collected aseptically from cockatiel chicks were serially diluted in 1.0 percent reduced peptone and inoculated into media by the pour plate method. Lactobacilli were enumerated by colony growth on LBS1 broth
plus agar; by characteristic Gram stain morphology; and by negative catalase test. Total enteric coliforms were counted from Mac Conkey Agar2. In addition, crop mucosal
scrapings were Gram-stained from these cockatiel chicks. Gut microbiology was performed on parent-raised cockatiels of 1, 5 and 6 months of age. The birds were killed by cervical dislocation and specimens from the gut sampled immediately. Crop contents, and crop, small intestine, and large intestine tissues were homogenized and serially diluted as before. All samples were inoculated by the above method to LBS plus agar, Mac Conkey Agar and Streptosel Agar3 (selective for Streptococcus in mixed cultures).
Results - Growth
Chicks fed the 5% solids mixture of the 20% protein diet grew more slowly than the chicks fed the 6.7% Solids mixture. The two chicks fed the 5% solids diet died at 15 and 18 days while all 3 chicks fed the 6.7% solids diet survived 29 days or longer and reached weights ranging from 75 to 88 grams, though none reached weaning.
Cockatiel Chicks fed the 20% protein diet reached a mean weight of approximately 10 grams during the first week. When they subsequently were fed a protein free diet, they maintained their weights for 5-7 days, and then died. Chicks fed 8%, 12%, and 20% protein diets grew at different rates until, after 10 days on the diets, their mean weights (+ standard deviation) were 22.60 + 1.78 g, 28.55 + 2.20 g, and 40.47 + 2.14 g, respectively.
Results — Disease
Chicks began to show signs of disease when the younger chicks were about two weeks old. Crop emptying slowed and weight gain ceased. In some cases chicks died within 1-2 days of showing symptoms. Other chicks lived as long as two weeks with on-going general fluctuations in weight (as much as 10 grams) between days. All 17 chicks except the 5% solids group and group fed the protein free diet died with these symptoms. The birds in these two groups died earlier.
Gram-stained mucosal scrapings from the sick cockatiel chicks revealed high numbers of Gram-negative short rods. These bacteria were present in the squamous epithelium of the crop and in the crop contents. More coliforms than lactobacilli were found in the crop contents of the sick chicks. Microbiology performed on older parent-reared cockatiels is presented in Table 2. Bacteria numbers are expressed as log10 colony forming units (c.f.u.) per gram of contents or tissue sampled. Lactobacilli numbers were highest in the crop contents of the one month old cockatiel (8.5) and lower in the older cockatiels (6.99 to 5.00). No significant differences were observed in lactobacilli numbers in tissues from the crop, small intestine and large intestine. Streptococci were slightly higher in the crop contents of the one month old cockatiel, but no differences were observed in the tissues. Coliforms were slightly higher in the crop contents of the young cockatiels, but were lower in older cockatiels. No differences were observed in coliform numbers from tissue samples.
Numbers of bacteria found in the digestive tract of cockatiels
Log10 Colony Forming Units (c.f.u.)/gram
Type Bird Age
Bacteria Months Contents Tissue
Crop Crop Small Intestine Large Intestine
1 >8.50 >7.50 <4.00 5.75
6 6.99 7.07 <4.00 <4.00
5 5.00 ---- 5.50 5.65
1 6.20 4.15 <3.00 <3.00
6 5.40 5.90 <3.00 <3.00
5 5.10 ---- <4.00 <4.00
1 3.0 3.0 <2.0 3.3
6 2.0 <2.0 <2.0 <2.0
5 <2.0 --- <3.0 <3.0
Discussion and Conclusions
Successful rearing of cockatiel chicks requires a diet with more than 5% solids. This is apparent from the better growth and survival of chicks fed a diet containing 6.7% total solids than of chicks fed the 5% solids diet. Whether an even more concentrated diet would provide better growth cannot be determined from these experiments. Diet conditions were not optimal, however, and the possibility that water intake was excessive should be considered further.
The responses of the chicks to increased levels of protein in the diet suggests that 12% protein is less than the requirement for maximum growth.
Sick cockatiel chicks revealed high numbers of coliforms and low numbers of lactobacilli; the reverse was found in healthy cockatiel chicks. This indicates that coliforms may be involved directly or indirectly with mortality of these hand reared cockatiels. Gut microbiology of parent-fed cockatiels is similar to that of healthy cockatiel chicks, where numbers of lactobacilli were higher than coliforms. Possibly as in other species, lactobacilli help to control coliforms until the cockatiel chick develops its normal gut microflora.
1 LBS Broth, BBL Microbiology Systems, Becton Dickinson and Co., Cockeysville, Maryland.
2 Defco Bacto Mac Conkey Agar, Defco Laboratories, Detroit, Michigan.
3 Streptosel Agar, BBL Microbiology Systems, Becton Dickinson and Co.,