Effects of dietary supplementation of heat-killed Lactobacillus plantarum L-137 on growth performance and immune response of bighead catfish (Clarias macrocephalus)

Abstract

The aim of this study was to determine the effects of heat-killed Lactobacillus plantarum L-137 (HK L-137) on the growth performances and immune response of juvenile bighead catfish (Clarias macrocephalus). The experiment was conducted with four iso-nitrogenous (44.8 % crude protein) and iso-caloric (20.17 KJ g−1) diets supplemented with different levels (0, 10, 20, and 50 mg kg−1) of HK L-137. The bighead catfish (n = 1800, average body weight: 9.69 ± 0.24 g) were randomly introduced to 200-L composite tanks (filled with 150 L of fresh water) and stocked at 150 fish tank−1 in triplicates per dietary treatment for 60 days. The results showed that the diets supplemented with 10, 20, and 50 mg kg−1 of HK L-137 significantly increased the growth, protein efficiency ratio, feed conversion ratio, survival rate, and lysozyme activity compared to the control. Furthermore, the diets supplemented with 20 and 50 mg kg−1 or 10 and 20 mg kg−1 of HK L-137 significantly enhanced the total white blood cell count or apparent digestibility coefficient of the fish, respectively. The fish fed the HK L-137 diets (at 10, 20, and 50 mg kg−1) revealed lower cumulative mortality than the control after challenge with Aeromonas hydrophila. Our results suggested that dietary supplementation of 10 mg kg−1 HK L-137 is the most efficient in improving the performance and immunity of bighead catfish; however, this should be confirmed in further study under full-scale commercial trials.