Effects of oral administration of acidifier and probiotic on growth performance, digestive enzymes activities and intestinal histomorphology in Salmo trutta caspius (Kessler, ۱۸۷۷)

This study was aimed to evaluate the single and combined effects of acidifier and probiotic on growth performance, digestive enzymes activities and intestinal histomorphology of Salmo trutta caspius. The juvenile fish with mean body weight ۱۵±۳ g were divided into ۸ different treatments (in triplicates), including control, ۵, ۱۰ and ۱۵ g sodium diformate kg-۱ diet, respectively as T۱, T۲ and T۳. Treatments namely T۴, T۵, T۶ and T۷ were received diets containing ۰.۲ g kg-۱ commercial probiotic Bio-Aqua® in combination with ۰, ۵, ۱۰ and ۱۵ g sodium diformate kg-۱ diet for ۶۰ days, respectively. The results showed that T۲ and T۳ fish growth performance were improved significantly (p<۰.۰۵), following ۳۰ days after administration, while T۱ did not show the same pattern over the ۶۰ days (p<۰.۰۵). The single probiotic treatment did not induce significant improvements in fish growth rate, digestive enzymes activities and intestinal morphometry though the combined treatments have been showed an intermediate level of improvement. The higher levels of chymotrypsin and trypsin have been observed at day ۳۰ and the higher activities of lipase, protease and amylase could be seen at day ۶۰ in the most acidifier treatments (p<۰.۰۵). The villi height and the thickness of epithelium have been reduced (p<۰.۰۵) because of single acidifier while the combined treatments led to either significant increase (p<۰.۰۵) or no change compared with corresponding single treatment. The addition of ۱.۰ g sodium diformate kg-۱ diet can improve the fish growth rate in long-term by changing digestive enzymes activities, and combined treatments of probiotic and acidifier are mostly revealed antagonist effects.

Keywords:

Sodium diformate , Dietary organic acids , Growth performance , Enzyme activity , Caspian trout.