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.