SEAWEED Kappaphycus alvarezii AS FEED SUBSTITUTION IN WHITE SHRIMP Litopenaeus vannamei POST LARVAE 10 NURSERY

• Main Author: KUSUMA HARDJANI (NIM : 30612003), DONNY
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/26756
• Institution: Institut Teknologi Bandung

<p align="justify">The decline in captured fisheries production encourages the development of aquaculture sector. One of the most important commodities in aquaculture is white shrimp Litopenaeus vannamei. Generally, aquaculture system in Indonesia is still conventionally cultivated and low control in the cultivation system causes several problems, with one of them being vibriosis syndrome. In aquaculture, seaweed is commonly used as feed for its antioxidants, antipathogen, and immunostimulant capabilities. Carrageenan in seaweed can potentially be used as an immunostimulant on white shrimp and increase vibriosis syndrome resistance. Kappaphycus alvarezii is a type of seaweed which contain about 67.3% of carrageenan. However, its protein and fat contents are lower than conventional feed. To be used as feed substitute, K. alvarezii needs to undergo pretreatments to increase its nutritional value. Fermentation using Saccharomyces cerevisiae yeast and the addition of Spirulina sp. are two processing techniques conducted in this study to increase the nutritional value of K. alvarezii. This study aims to obtain the best composition for K. alvarezii which can increase shrimp resistance to vibriosis syndrome without decreasing its growth and water quality. Furthermore, this study also aims to know the effect of feed substitution on microbial community activities and structures operated on the nursery system. <br /> <br /> Fermentation process of K. alvarezii using S. cerevisiae was conducted with several inoculum variation; 5% (v/v), 10% (v/v), and 15% (v/v). Each treatment was repeated for 3 times. Nutritional analysis was performed using proximate methods, HPLC for amino acid contents, and GC - MS for fatty acid contents. The best yeast growth rate and nutritional contents was observed in K. alvarezii seaweed fermented using 10% (v/v) inoculum, having a growth rate of 0.38 ± 0.05 h-1, and nutritional contents which improve L. vannamei resistance to vibriosis syndrome include 5.78 % of fermented carrageenan, ± 20% amino acid , and ± 48% fatty acids. <br /> <br /> The effect of several feed subtitution formulas in L. vannamei post - larvae 10 at the nursery stage was observed with two tests; a performance test (14 days) and a challenge test using V. harveyi bacteria (7 days). The tests was conducted for three times, using various composition of K. alvarezii without fermentation, K. alvarezii added with Spirulina sp., and fermented K. alvarezii. The nursery was kept as a batch system under controlled conditions. The final test shown that feed <br /> <br /> subtitution with 1.5% of fermented seaweed had 95.28% survival rate in the performance test and 97.33% in the challenge test, the highest increase in white shrimp’s survival rate compared to other treatments. The number of V. harveyi bacteria increases with the duration of the nursery period, both in water and shrimp samples. By the end of the challenge test, the number of V. harveyi bacteria is at the lethal dose (106 CFU). Increased resistance and survival rate of white shrimp against vibriosis syndrome was possibly caused by carrageenan, fermented carrageenan, amino acids and fatty acids content in the diet which activated and enhanced shrimp immune system. Nevertheless, it was shown that all substitution treatments had no effects on growth parameters (biomass, average weight, average length, FER, FCR), water physical quality parameters (salinity, temperature, pH and DO) and water chemical quality parameters (ammonia, nitrite and nitrate) when compared to control. <br /> <br /> Microbial community activity testing was performed using ecoplate on all treatments, while isolation, purification and identification methods (16sRNA) for microbial community structure analysis was performed only on the best treatment observed. Various compositions of K. alvarezii in feed subtitutions decreased the activity of carbon substrate utilization by microbial communities in both water and shrimp gastrointestinal tracts compared to controls. Changes in microbial community activity are caused by the more complex feeding contents, antimicrobial contents in the diet and changes in the amount of substrate contained in water and gastrointestinal tracts. Community structure for the best treatment consists of several genera of Alcaligenes, Bacillus, Microbacterium and Myroides found on both water and shrimp samples, while Brachybacterium and Pseudomonas only found on shrimp samples. Microbacterium, Myroides and Brachybacterium genus are found only in seaweed substitution treatment. Bacteria from Microbacterium and Myroides genus have the ability to use polymer, carbohydrates, carboxylic acids, carbon phosphates, amino acids and amines group substrates, whereas Brachybacterium genus is specifically capable to utilize xylan substrates. Bacillus bacteria was found to be dominant on water samples during all nursery phases, whereas Pseudomonas bacteria was dominant at the beginning of nursery phase and Bacillus bacteria was dominant at the end of nursery phase. Bacillus and Pseudomonas have catabolism enzymes to degrade several substrate groups, such as polymer, carbohydrates, carboxylic acids, carbon-phosphates, amino acids and amines. Bacillus, Alcaligenes and Pseudomonas bacterias were able to produce antimicrobials substanced based on their ability to use itaconic acid substrate. Increased survival rate of white shrimp at nursery phase may not only be influenced by nutritional compositions in fermented seaweed, but also influenced by activity and microbial community structure on water and shrimp gastrointestinal tract.<p align="justify">