Viability of Different Strains of Lactobacillus fermentum in Feed and Effects on Growth Performance of Clarias gariepinus Fry

Abstract

Globally, aquaculture has developed significantly; however, poor performance at larvae stage is still a challenge. The use of antibiotics has post-application effects in aquaculture hence the demand for eco-friendly alternatives. The Lactobacillus fermentum strains BCS27 and F4S8 isolated from fermented maize and cassava respectively were supplemented in six isonitrogenous (55% protein) fry diet in three different concentrations (3x10⁷, 6x10⁷ and 9x10⁷cfu/ml/100g) with a positive (T₀) and negative (AT₀) controls. The strain BCS27 were included in these concentrations to give treatments LF₁T₁, LF₁T₂, LF₁T₃ while strain F4S8 represented treatments LF₂T₁, LF₂T₂, LF₂T₃. Three-day old Clarias gariepinus larvae (0.005g) were fed to satiation for eight weeks in a completely randomized design. The highest mean weight gain (MWG) of 0.4116±0.02g and specific growth rate (SGR) of 0.9765±0.05%/day were recorded in LF₁T₁. Quadratic regression analysis of growth indices against microbial counts revealed that at concentration of 50.7CFU/ml the best weight gain of 0.39g was obtained. The treatment LF₁T₁ also produced the highest protein efficiency ratio (PER) (0.007±0.0003) and nitrogen metabolism (NM) (4.86±0.23). Survival was significantly low (22.5±5.1%) in AT₀ while the highest value (42.3±3.18%) was recorded in LF₁T₁. Amongst strain F4S8, LF₂T₁ had significantly higher (p<0.05) MWG (0.4197±0.01g). The optimum treatment concentration was 62.5CFU/ml at 0.33g MWG. The treatment LF₂T₁ also had the best PER of 0.007±0.000 while T₀ recorded the least value (0.003±0.0004). The highest survival (44.2±1.5%) was recorded in LF₂T₂. The studied L. fermentum strains was viable in the feed which successfully improved the performance and nutrient utilization in C. gariepinus larvae. Thus, it’s application in fish feed production is recommended.

Keywords: Lactobacillus fermentum, growth, C. gariepinus, fry, larvae.