- Title
- An investigation into the effect of dietary protein and fishmeal replacement in juvenile Yellowtail, seriola lalandi (pisces: carangidae) in a recirculating aquaculture system
- Creator
- Manjingolo, Apelele https://orcid.org/0000-0003-3914-4821
- Subject
- Yellowtail
- Subject
- Integrated aquaculture
- Subject
- Yellowtail fisheries
- Date
- 2023-01
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10353/27489
- Identifier
- vital:67332
- Description
- The yellowtail kingfish, Seriola lalandi, is a carnivorous species, which require high levels 40 Percent of protein in its diet of which a significant portion comes from fishmeal. Fishmeal is usually the main ingredient when formulating a diet for carnivorous fish because of its high protein content, good digestibility and balanced essential amino acid profile. The use of fishmeal in diet formulations has decreased because of high prices and short supply. Aquaculturists have little alternative but to reduce the amount used or replace it with alternative suitable protein sources. This study aimed to contribute to the optimization of protein requirements and fishmeal replacement in the diet of juvenile yellowtail in a Recirculating Aquaculture System RAS. This study was conducted at the marine finfish farm, Kingfish Enterprises Pty Ltd in the East London Industrial Development Zone ELIDZ in a purpose designed RAS. The first experiment investigated the effect of dietary protein level on survival, growth, food conversion ratio FCR and health of juvenile yellowtail in a RAS. Four iso-calorific diets containing different dietary protein levels 38 Percent , 44 Percent , 50 Percent and 56 Percent were formulated. Each diet was fed to three RAS tanks holding juvenile yellowtail 30 fish per tank for 49 days. Dietary protein levels did not influence survival of juvenile yellowtail. Specific growth rate SGR p equal 0.003) was greater in fish fed 56 Percent protein compared to fish fed 38 Percent protein but there were no differences between the 56 Percent , 50 Percent and 44 Percent protein diets. There were no differences in protein efficiency ratio PER between the four diets. FCR decreased with increasing protein level with fish being fed the 56 Percent protein yielding the lowest FCR 1.26 compared to fish fed 38 Percent protein 1.76 p equal 0.003, however, there was no difference between the 44 Percent , 50 Percent and 56 Percent protein levels. The hepatocytes of fish fed high dietary lipid content diet with 38 Percent and 44 Percent protein showed large lipid vacuole zones in the cytoplasm p greater 0.001. Body protein, ash, moisture, and lipid was not affected by different dietary protein levels. In terms of producing a diet with best growth at the lowest cost, a 44 Percent protein diet is considered as optimal for juvenile yellowtail in RAS. The second experiment investigated the effect of partial and full replacement of fishmeal with a mixture of alternative protein sources chicken meal, blood meal, and soybean meal in equal proportions that are more sustainable and less costly. Four experimental diets were formulated to be iso-nitrogenous 44 Percent protein and iso-calorific 19.50 Mg/Kg as follows: 1 a control diet with fishmeal as the only protein source which was the same formulation as the 44 Percent diet used in the first experiment, 2 control diet in which 33 Percent of fishmeal was replaced with the protein mixture, 3 control diet in which 67 Percent of fishmeal was replaced with the protein mixture and 4 control diet in which 100 Percent of fishmeal was replaced with the protein mixture. Different fishmeal levels in the diets did not have an effect on the survival on juvenile yellowtail. Specific growth rate SGR was greater for fish fed 67 and 100 Percent fishmeal p equal 0.017 compared to fish fed 0 Percent fishmeal. There were, however, no differences in SGR between fish fed 33, 67, and 100 Percent fishmeal. Condition factor CF was significantly affected by the interaction between dietary treatment and time with average values lower at the end of experiment compared to the start of the experiment. On day 28 p equal 0.02 and 49 p equal 0.01, CF of fish fed 67 and 100 Percent fishmeal diet differed significantly from those fed the 0 Percent fishmeal diet but 33, 67, and 100 Percent fishmeal diets did not differ from each other . Feed conversion ratio FCR was significantly affected by fishmeal replacement with fish on fishmeal-containing diets showing lower FCRs compared to those on fishmeal-free diets p equal 0.001. Fish fed diets containing 67 and 100 Percent fishmeal had low PER 0.026 compared to fish fed 0 Percent fishmeal. There were, however, no differences in PER between fish fed 33, 67, and 100 Percent fishmeal. Hepatosomatic index HSI was not affected by levels of fishmeal replacement in the diet. Body protein, ash, moisture, and lipid was not affected by partial and full replacement of fishmeal. The results indicate that full replacement of fishmeal 0 Percent diet had the worst SGR, FCR, and PER. The remaining three diets were statistically similar which suggests that a diet with 33 Percent fishmeal produces as good growth, FCR and PER as 67 and 100 Percent fishmeal diets. However, as there were also similarities in SGR and PER for the 0 and 33 Percent fishmeal diets, it is therefore recommended that future studies focus on the region between 33-67 Percent to find the optimal break point for the various growth indicators. This study has provided foundation for the formulation of yellowtail kingfish diet which is suitable for use in a RAS.
- Description
- Thesis (MSci) -- Faculty of Science and Agriculture, 2023
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (vi, 75 leaves)
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
- Rights
- All Rights Reserved
- Rights
- Open Access
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UFH Department of Zoology & Entomology
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details | SOURCE1 | A Manjingolo- MSc Thesis Revised.pdf | 1 MB | Adobe Acrobat PDF | View Details |