Research Article: Autochthonous probiotic in Asian sea bass (Lates calcarifer) diet: reduces excessive liver lipid deposition and resistance against Streptococcus iniae infection

Aquaculture represents a pivotal economic sector worldwide, meeting the escalating food demands of the expanding global population. Consequently, this research aimed to assess the incidence of fatty liver in Asian sea bass (Lates calcarifer) subjected to a diet enriched with lactic acid bacteria and evaluate their survival against Streptococcus iniae infection. The present study examined ۲۴۰ sea bass (۱۰۹ ± ۱۰.۵ g average weight) that were randomly assigned into four treatments with three replicates (۲۵ specimens per treatment) for ۶۰ days. The treatments comprised the following: First treatment: fish were fed with commercial feed. Second treatment: fish were provided with feed containing ۱۰۹ CFU/g of Lactobacillus plantarum bacteria. Third treatment: fish were fed with feed containing ۱۰۹ CFU/g of Lactobacillus pentosus bacteria. Fourth treatment: fish were provided with feed having ۱۰۹ CFU/g of L. pentosus bacteria combined with L. plantarum in equal proportions. At the end of the experiment, the growth performance, the survival rate against the pathogenic bacteria S. iniae and the amount of fatty liver were evaluated. The findings disclosed enhanced growth indicators in the second treatment (strain ۱۴۰) during the initial ۳۰ days. Furthermore, statistically significant disparities were noted in the third treatment (۲P) concerning PER, SGR, WG, RGR, and DWG during the subsequent ۳۰-day period (P<۰.۰۵). Liver pathology examination demonstrated that most treatments resulted in the development of fatty liver. However, the third treatment (L. pentosus) exhibited the lowest incidence of fatty liver when endogenous probiotics were incorporated into the diet. Post-challenge with S. iniae, the mortality rate in the probiotic treatments L. pentosus (P۲) and L. plantarum (۱۴۰) significantly surpassed that of the control group (P<۰.۰۵). The findings underscore the absence of synergistic interactions between the two experimental probiotics on the ۶۰th day, as the combined group displayed diminished growth performance compared to the individual groups. Moreover, the use of L. plantarum and L. pentosus bacteria, particularly the latter, has been shown to significantly improve several growth indicators, as well as the food conversion ratio. Consequently, these probiotics are recommended as dietary supplements for Asian sea bass.

کلیدواژه ها:

Indogenous probiotic ، Bacteria ، Growth ، Fatty liver ، Streptococcosis ، Asian sea bass ، Growth performance ، Fatty liver change Streptococcus iniiae ، Asian sea bass.