Selective Probiotics Mix Mechanism of Action in Gut of Empurau (Tor tambroides) Fingerlings

Sing Ying, Chua (2024) Selective Probiotics Mix Mechanism of Action in Gut of Empurau (Tor tambroides) Fingerlings. Masters thesis, FACULTY RESOURCE SCIENCE AND TECHNOLOGY.

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Abstract

Tor tambroides, commonly known as Empurau or Malaysian mahseer, is Malaysia's most valuable freshwater fish and is native to Sarawak. Its substantial market value that pond reared Empurau is sold at RM500 per kilogram, led to Empurau (T. tambroides) increased popularity among fish farmers in Malaysia. However, this fish grows slowly, taking two to three years to reach a size that is marketable. Such an extended growth period underscores the importance of effective feeding management for maintain fish health. Probiotics have been shown to improve growth performance, feed utilization, immune response, and disease resistance in aquaculture. Lacto-sacc is the mixture of probiotics Lactobacillus acidophilus and Saccharomyces cerevisiae commonly used as feed additives and a substitute for antibiotics in the diet. This research aims to evaluate the selective probiotics mix mechanism of action in gut of Empurau (Tor tambroides) fingerlings. The fingerlings, with an average body weight of 6.53g ± 0.17g, were stocked into twelve 650L tanks at a rate of 50 fingerlings/tank. Four experimental diets were formulated with 40% protein and supplemented with different concentration of Lacto-sacc forming 4 experimental diets; control diet (A), 0.5% Lacto-sacc (B), 1.0% Lacto-sacc (C) and 1.25% Lacto-sacc (D). The fingerlings were fed twice a day with 5% of the average body weight for 20 weeks in probiotics feeding trial (phase 1). The 8-week post-probiotics feeding trial (phase 2) was continued with commercial fish feed. Parameters including growth performance, feed utilization, relative protein digestibility, digestive enzyme activity and gut microbiota of T. tambroides were recorded. In both feeding trials, the study showed no significant difference (p>0.05) in most of the parameters except lipase activity phase 1 and gut microbiota phase 2. However, Empurau fed with a diet supplemented with 0.5% Lacto-sacc (B) showed the highest numerical values and trends in most of parameters studied except lipase activity. Treatment B probiotics feeding trial showed the highest weight gain, specific growth rate (SGR), lipase and protease activity with lowest feed conversion rate (FCR) compared to other treatments. On the other hand, 1.25% Lacto-sacc (D) gave the best numerical results and trends in post-probiotics feeding trial with best growth performance and better overall parameters. The dominant phyla found in gut of T. tambroides in both phases were the same which more than 95% were comprised by Fusobacteria, Proteobacteria, Bacteroidetes and Firmicutes. The dominant genera found in both phases were Cetobacterium (Fusobacteria), ZOR0006 (Firmicutes), Brevinema (Spirochaetes), and Aeromonas (Proteobacteria). It is noticeable that the preferred concentration in each phase; 0.5% Lacto-sacc of Phase 1 (BP1) and 1.25% Lacto-sacc of Phase 2 (DP2) has lower Fusobacteria and an increase in other dominant bacteria compared to other treatment in their respective phases. The inclusion of Lacto-sacc to T. tambroides did benefit to the fish growth, feed utilization, digestive enzyme activities and provided a more even distribution and diverse gut microbiota.

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