Effects of heat killed Lactobacillus plantarum (LP20) supplemental diets on growth performance, stress resistance and immune response of red sea bream, Pagrus major

•No previous work has addressed the effect of probiotic for Pagrus major.•Fish performances were improved by heat-killed Lactobacillus plantarum (HK-LP).•Enhancement of Pagrus major immune responses by HK-LP•Enhancement of antioxidant status of Pagrus major•The optimum supplement of dietary HK-LP for Pagrus major is 0.1%.

A feeding trial was carried out to determine effects of heat-killed Lactobacillus plantarum (HK-LP) for red sea bream (Pagrus major). Five dietary levels of a commercial product containing 20% HK-LP at 1, 10, 100, 1000, and 2000 mg kg− 1 diets were supplemented to the basal diet (control), respectively. Triplicate groups of fish (initial weight: 11 g) were stocked in 100-L polycarbonate circular tanks at a density of 12 fish per tank under the flow-through system, and were fed the respective test diets for 56 days. At the end of a feeding trial, the results showed that the fish fed the diet at 10, 100, 1000 and 2000 mg kg− 1 HK-LP significantly grew faster than control group. Similarly, significantly improved feed intake, feed efficiency ratio, protein retention, and apparent digestibility coefficients were also found at 1000 mg kg− 1 HK-LP group than those in HK-LP free group. Some parameters such as serum lysozyme activity, total serum protein, mucus secretion, and the tolerance against low salinity stress were improved in fish fed 1000 mg kg− 1 HK-LP compared to those in HK-LP free group. This study demonstrated that HK-LP enhanced non-specific immune defense system of red sea bream, providing them with higher resistance to the stress and better immune response.