Vahid Morshedi

The combined use of prebiotics and probiotics, known as synbiotics, has been suggested to improve fish growth and health status. Thus, the present study was aimed to evaluate the effects of single and combined use of Lactobacillus plantarum (LP) and xylooligosacharide (XOS) on growth performance and immunity of sobaity (Sparidentex hasta). Fish with an average weight ± SE of 35.64 ± 0.30 g were fed four experimental diets including a basal diet (with no supplementation as control), T1 (basal diet + 5 g kg􀀀 1 XOS and 106 CFU g􀀀 1 LP), T2 (basal diet + 10 g kg􀀀 1 XOS and 106 CFU g􀀀 1 LP), T3 (basal diet + 106 CFU g􀀀 1 LP) until apparent satiation for 8 weeks. Results showed that growth, feed utilization, and body composition parameters were not significantly affected by different treatments (p > 0.05). Amylase and lipase were significantly enhanced in T3 when compared to the control group. Blood indices were not affected however lower white blood cells were found in fish from T3. In terms of total immunoglobulin and lysozyme activity, no significant improvement was noticed in fish fed different diets (p > 0.05) while the expression level of IL-1β was significantly higher in all treatments when compared to control. The expression level of growth-related gene (IGF-I) in fish from T1 was found significantly different from that of control treatment (p < 0.05). The present findings illustrated that single or combined supplementation of LP and XOS did not induce positive effects on growth performance of sobaity while positive responses were noticed at molecular level urging further research to test different combinations.