PENGARUH PAKAN YANG DISUPLEMENTASI SINBIOTIK TERHADAP KINERJA PERTUMBUHAN IKAN NILA (Oreochromis niloticus, Linnaeus, 1758). = THE EFFECT OF DIETARY SYNBIOTICS SUPPLEMENTATION ON GROWTH PERFORMANCE OF NILE TILAPIA (Oreochromis niloticus Linnaeus, 1758)

GENERAL ABSTRACT AYMAN ALAMEEN MOHAMMED ABDALRHMAN, L013211010 “The Effect of Dietary Synbiotics Supplementation on Growth Performance of Nile Tilapia (Oreochromis niloticus Linnaeus, 1758)” supervised by Siti Aslamyah, Zainuddin, and Muhammad Iqbal Djawad. ________________________________________ Background. Nile tilapia (Oreochromis niloticus) is the most widely farmed freshwater fish species worldwide. Improving efficiency and reducing feed costs are major challenges. Functional feed additives, such as synbiotics, have the potential to enhance fish growth and improve nutrient absorption. Objectives. This study aimed to isolate and characterize inulin from sweet potatoes (Ipomoea batatas L.), determine the optimal synbiotics combination between inulin and multi-species probiotics through an in vitro evaluation, and evaluate the effects of the synbiotics combination on the growth performance, feed digestibility, enzyme activity, chemical body composition, and liver histology of Nile tilapia. Methods. Inulin was extracted from sweet potatoes using rotary evaporation and freeze-drying methods, then characterized via Fourier Transform Infrared Spectroscopy (FT-IR). The experiment was conducted in a factorial completely randomized design with three factors: inulin concentration (0, 1, 3, and 5 mL), culture media (nutrient agar and potato dextrose agar), and incubation time (24 and 48 hours). to determine the optimal synbotics combination between inulin and multi-species probiotics. Finally, a total of 225 Nile tilapia (1.30 ± 0.93 g) were stocked (15 fish/aquarium) and fed for 50 days at 7% biomass. A basal diet without synbiotics served as a control, while four diets included inulin (1.5, 2.5%, 3.5%, and 4.5%) combined with multi-species probiotics (1 mL Bacillus spp., 1 g Rhizopus sp., and 1 g Saccharomyces sp.). Results. The freeze-dryer method yielded inulin with higher total and sugar reduction and a lower degree of polymerization than the rotary evaporator method. Proximate analysis showed differences between two methods, while FT-IR spectra confirmed the presence of inulin in both samples. Result of in-vito evaluation indicated significant effects (P < 0.05) of inulin concentration and incubation time on microbial growth. Higher inulin concentrations led to an increase in the growth of all probiotics. Additionally, higher doses of inulin fostering protease activity and lower doses being more conducive to amylase activity. After the feeding trial, fish fed synbiotics with 3.5% inulin showed the highest final biomass, biomass gain, average daily gain, specific growth rate, protein efficiency ratio, and lowest feed conversion ratio (P < 0.05). Survival rates and digestibility showed no significant differences (P > 0.05). Amylase activity showed no significant differences (P > 0.05), while protease activity was higher in fish fed 3.5% and 2.5% inulin (P < 0.05). Chemical body composition showed reduced water content (79.43% to 70.49%) and increased lipid and ash content (P < 0.05), with no significant differences in protein or nitrogen-free extract (P > 0.05). Liver histology showed enhanced hepatocyte structure in fish fed 3.5% and 2.5% inulin. Economic analysis indicated diet 4 had the highest efficiency and profit. Conclusion. The combination of 3.5% inulin and multi-species probiotics significantly enhanced growth performance, feed digestibility, enzyme activity, and liver health in Nile tilapia, offering an economically viable solution for Nile tilapia farming.