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

摘要

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.