Synbiotic application to enhance growth, immune system, and disease resistance toward bacterial infection in catfish (Clarias gariepinus)

Abstract

Lactobacillus casei (LC) on catfish (Clarias gariepinus var.) feed to enhance growth, feed efficiency, and resistance toward Aeromonas hydrophila and Pseudomonas fluorescens bacterial infection. Five different pellet types were made by adding various composition of SFE and LC as follows: pellet 1 (0 SFE + 0 LC), pellet 2 (0 SFE + 10 g kg−1 LC), pellet 3 (2 g kg−1 SFE + 10 g kg−1 LC), Pellet 4 (4 g kg−1 SFE +10 g kg−1 LC), Pellet 5 (6 g kg−1 SFE +10 g kg−1 LC). In total, 150 Catfish (initial weight ± 4 g) were randomly distributed into 15 plastic boxes and cultured for 12 weeks. Catfish were fed with different composition pellets for two weeks, followed by a regular pellet. The observation of growth was examined in weeks four and eight after feeding time. In week 8, the bacterial challenge against A. hydrophila and P. fluorescens was performed, and the observation was continued until week 12. The results showed that catfish grew to weigh an average of 45 g in week 8. Catfish fed higher concentrations of SFE and LC extractions showed a specific growth rate significantly higher (8–9%) than that of the control-treatment catfish. Additionally, SFE and LC extractions enhanced immune system function between weeks four and eight in comparison with other treatments. Resistance against bacterial infection increased with the SFE extraction to reach 99.65–100%. Fish feed containing only the LC extraction also showed higher resistance than controltreatment feed. In conclusion, higher concentrations of SFE and LC extractions in catfish feed has been shown to enhance growth, with no attendant risk. Importantly, the use of the synbiotics enhanced both the immune system and resistance to A. hydrophila and P. fluorescens bacterial infections.