Starter diets for channel catfish : effects of formulation on growth and body composition.
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1983.
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| Subjects: | |
| Online Access: | Link to ProQuest Copy Link to OAKTrust copy |
| Abstract: | Production type diets were developed to support tank reared channel catfish, lctalurus punctatus, until they were large enough to accept conventional pelleted rations. This was accomplished through a series of feeding trials with diets formulated by computer and using ingredients commonly available in feed mill inventories. An adequate minimum particle size for swim-up fry was found to be in the range of 0.35-0.50 mm. Growth rate of advanced fry did not appear to be limited by such a fine feed grind, as might be expected if significant nutrient leaching had occurred. A high level of crude protein (about 52% on a 90% dry matter basis) and a high protein:energy ratio (126 mg digestible protein/kcal digestible energy) supported maximum growth among swim-up stage fry. The minimum requirement appeared to decline with growth to about 50% (P:E = 122) at 0.2 g, 48% (P:E = 117) at 1.7 g and may be as low as 41-44% (P:E = 100) from 3-5 g average fish weight. Carcass composition of fry was significantly affected by dietary protein content. However, the principal effect of diet upon carcass composition during the present study appeared to be through changing the rate of gain. Carcass ash, protein and fat all increased at the expense of moisture, as the fish grew. Trials were also conducted to identify and evaluate alternative ingredients for starter diets. Fish meal was successfully reduced to supply about half of the protein in the diet of swim-up fry. The level of fish meal needed by advanced fry (3-5 g) was flexible within wide limits when the fish were fed balanced diets formulated to provide adequate levels or digestible protein and indispensible amino acids. Several animal and vegetable protein concentrates partially replaced fish meal without significant reductions in growth or changes in carcass composition. Ingredients that performed especially well included fish, poultry byproduct, soybean and cottonseed meals; brewers yeast; wheat grain and tallow. Ingredients thought to be essential or included in the past for their "unidentified growth factors" were apparently not necessary when balanced diets were manufactured with proper quality controls. Certain changes to diet formulae apparently resulted in micronutrient deficiencies, as did extended storage. No diet was found superior to those made of fish meal, wheat, tallow and a micronutrient premix preserved with antioxidants and proprionic acid. |
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| Item Description: | "Major subject: Wildlife and Fisheries Sciences." Typescript (photocopy). Vita. |
| Physical Description: | x, 95 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 84-94). |