M. Hoseinpouri Ghasemabad Sofla - Department of Fisheries Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
M. Soltani - Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
T. Mohammadian - Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
M. Shamsaie Mehrgan - Department of Fisheries Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran

This study was aimed to evaluate the single and combined effects of sodium diformate as an acidifier and bacilli probiotics (Bacillus subtilis and B. licheniformis) on some immunological, oxidative stress and biochemical responses in juvenile Salmo trutta caspius for ۶۰ days. Hundred juvenile fish weighing ۱۲.۶±۱.۴ g was divided into ۴ different treatments, including control, ۰.۴ g B. subtilis+B. licheniformis /kg diet, ۰.۵ g sodium diformate/kg diet and their combination (۰.۴ g B. subtilis + B. licheniformis+۰.۵ g sodium diformate/kg diet). Blood samples (۹ fish/treatment) were withdrawn at two different time intervals (days ۳۰ and ۶۰). Results showed that bacilli probiotics treatment led to significant increases in the serum lysozyme and complement activities (ACH۵۰) at days ۳۰ and ۶۰, and sodium diformate only increased this parameter at day ۳۰ as compared with the control one. The ACH۵۰ indicated a significant decrease following sodium diformate treatment at the same time. Serum bactericidal activity was declined following either acidifier or probiotic treatment. Serum catalase activity was elevated in all treatments, either significant or insignificant as compared with control. Serum malondialdehyde (MDA) was not changed significantly during ۳۰ days of the experiment. On the contrary, bacilli probiotics and sodium diformate led to increase and decrease in MDA, respectively. Our data suggest that sodium diformate applied here was much more successful in improving the fish health status rather than bacilli probiotics. Combined treatment revealed a mid-level of responses except for ACH۵۰, in which a higher level was observed.

Acidifier, Probiotic, Antioxidant defense, Immunity system, Caspian trout