| Author | Santos, Emelita V. |
| Call Number | AIT Diss. no.AE-93-02 |
| Subject(s) | Fishes--Feeding and feeds
|
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral of Technical Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AE-93-02 |
| Abstract | The development of low—cost, high quality fish feed is a prerequisite for the development of cost effective aquaculture for small—scale farmers in developing countries. This study concerned the utilization of selected terrestrial plants and aquatic macrophytes by the herbivorous fish, silver barb (Puntius gonionotus) as factors affecting its growth, including nutrition are poorly understood. Experiment 1 on the absolute protein energy requirement of juvenile silver barb for maximum growth was based on a previous investigation in which silver barb was fed five isoenergetic semi—purified diets containing varying levels of dietary protein. The reported dietary protein requirement of 35% by weight was used as a basis in the formulation of the semi—purified diet used in this experiment which was fed to fish at levels of O, 0.5, 1, 2, 3, 4, 5 % body weight and ad libitum. The fish (2—2Og) required an absolute protein of 32 g/kg bw/d (1589 KJ/kg bw/d) and a digestible protein of 18 g/kg bw/d (703 KJ/kg bw/d) which was obtained by feeding the fish at a rate of about 9% body weight/day. The protein requirement for maintenance ranged from 0.96 to 1.24 g/kg bw/d (48 to 62 KJ/kg bw/d). The growth of silver barb was a positive curvilinear function of the feed ingestion. There was an inverse relationship between apparent protein digestibility and feed intake. Plants contain a high level of fibre which is poorly digested by fish‘ Since the amount of digestible energy and protein are important in the design of any feeding program, the apparent digestibility coefficients of six species of terrestrial plants and aquatic macrophytes were determined in Experiment 2. An apparent dry matter digestibility coefficient ranging from 50 to 64% was obtained for black amaranthus, passion fruit leaves, swamp morning glory and sweet potato while means of 5% and 24% were obtained for bitter cassava and the duckweed Lemna, respectively. The apparent protein digestibility coefficient of all plants ranged from 59 to 87%, except for bitter cassava which was only 24%. The oxygen consumption of fish feeding on these plants was also determined and compared. Nutritional value of these plants were evaluated in Experiment 3 based upon their level of available nutrients, particularly protein and its essential amino acids (EAA), to meet the requirement for fish growth. Evaluation was based on the essential amino acid profile of the plants and their chemical score (CS). Plants with a limiting EAA were combined with plants rich in this EAA and this combination was tested against the same plants fed singly. The experiment supported the hypothesis that a combination of plants can support a significantly higher growth rate than feeding with single plants. Dry matter and protein consumption of each plant were quantified. All plants tested supplied about 13 to 55 % of the digestible protein requirement of silver barb. The value of green fodder as a complete feed and as a supplementary feed was evaluated in a non—fertilized and fertilized ponds, respectively, using two diets 1 Fresh Plant Diet (FPD) and Practical Moist Diet (PHD) given to two sizes of fish. Small fish grew in a non—fertilized pond. Fertilization showed a positive significant effect on the growth of small, but not of large, silver barb. Supplemental feeds enhanced fish growth, with higher value obtained when fish fed FPD than PMD. Large fish lost weight in the non- fertilized pond and hardly grew at all when fed solely on natural food in the fertilized pond. However, addition of FPD and PMD as supplemental feeds significantly increased the growth, but poor water quality affected the feed intake and limited the growth of the fish fed on PMD. The significant growth of fish on FPD indicated the high value of green fodder (Lemna and swamp morning glory), not only as a supplementary feed, but also as a complete feed. The following feeding strategies are proposed based on this work. It is recommended to fertilize the pond water to produce natural food for the maximum growth of juvenile silver barb. Upon reaching the stage of herbivory, supplemental feeding is practiced based on two options depending on the availability of Lemna, which was the best feed for silver barb. Option 1 is suggested where Lemna is abundant. If the fish is fed with Lemna at the rate of about 8% bw/d (dry matter weight of Lemna and fresh weight of the fish) silver barb can be cultivated mainly on this diet until the desired size is attained. However, where Lemna is not abundant, option 2 is possible. A practical diet similar to PMD can be formulated for a feeding rate of about 5% bw/d, three times a day, until the fish reaches the stage of complete herbivory. Then, other available terrestrial plants in combination with Lemna can be given fresh at the rate of 1 to 1.3% bw/d and about 6% bw/d, respectively. Other farm by—products such as rice bran (1% bw/d) or other supplemental feeds can also be considered but precautions should be taken so as not to cause high loading rate of organic matter in the pond leading to the deterioration of water quality, particularly dissolved oxygen and total ammonia—nitrogen which are important factors for better growth and survival of silver barb. |
| Year | 1993 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AE-93-02 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Edwards, Peter; |
| Examination Committee(s) | Yakupitiyage, Amararatne;Demaine, Harvey;Little, David;Wee, Kok Leong; |
| Scholarship Donor(s) | Government of Australia; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1993 |