Effects of dietary supplementation with Pediococcus acidilactici MA18/5M, galactooligosaccharide and their synbiotic on growth, innate immunity and disease resistance of rockfish (Sebastes schlegeli)

The trial investigated the effects of dietary supplementation with the commercial prebiotic galactooligosaccharide (1% GOS; GOS diet), the commercial probiotic Pediococcus acidilactici MA18/5 M (6.3 log CFU g− 1 PA; PA diet) and their combination as synbiotic (1% GOS and 6.3 log CFU g− 1 PA; SYN diet) on the growth, innate immunity and disease resistance of juvenile rockfish (Sebastes schlegeli). Triplicate groups of fish (18.2 ± 0.3 g) were fed one of the four diets for 8 weeks and then subjected to a standard challenge with Edwardsiella tarda by intraperitoneal injection. The results showed significant (P < 0.05) improvement in growth performance in the SYN compared to the control group with intermediary benefits for PA and GOS. White blood cells count was significantly enhanced in the PA and GOS groups with a further significant increase for the SYN diet. In accordance and compared to the control; serum lysozyme and bacteriostatic activities against Vibrio anguillarum and Escherichia coli were increased in all supplemented groups while serum alternative complement activity was elevated in the SYN group. In addition, the skin mucus bacteriostatic activities were significantly influenced by dietary treatments. The beneficial effects observed on circulating innate immune parameters were validated by a higher survival pattern following intraperitoneal challenge with E. tarda in the PA and SYN groups. This study contributes to the knowledge on the mode of action of GOS and PA and demonstrates their potential as natural health and growth promoters in the rockfish on-growing aquaculture industry.