Effect of feeding strategy of probiotic Enterococcus faecium on growth performance, hematologic, biochemical parameters and non-specific immune response of Nile tilapia

The aquaculture industry is in considerable increases. Optimization of husbandary conditions in intensive aquaculture are in continuous interest. Probiotic was proved as promising factors to enhance fish production by remodeling intestinal microbial balance, boosting immune system and reducing antibiotic uses. The efficient strategy of probiotic uses and their protection of fish still making debate. The intake of tilpia fed with basal diet enriched with probiotic (Enterococcus faecium) and its response following to a challenge with pathogenic strain of Aeromonas hydrophila was studied. Four feeding strategies were tested and compared: continuous feeding with only basal diet (CTR), continuous feeding with probiotic-supplemented diet (CON), pulse-administration feeding of 7 days (P7) and 14 days (P14) alternation with probiotic supplemented diet and basal diet. Differences in growth rate, immune system modulation and biochemical parameters were evaluated. P7 strategy showed efficacy in promote fish growth conditions. Body chemical composition and blood biochemical parameters did not show any significative differences between feeding strategies. Burst respiratory analysis showed significant difference in fish fed with P14 strategy. After challenge test, CON strategy showed better fish protection against Aeromonas hydrophila. Enterococcus faecium enhance fish growth, boost imune system if administrated in 14 days period, and efficiently protect fish if it is continuously administrated.