Aim: The aim of this study was to investigate the effects of organic acids salts on growth performance, blood indices and activity of digestive enzymes of yellowfin seabream fingerling.
Methodology: For this experiment, 200 Yellowfin seabream (A. latus) fingerling with an average weight of approximately (6.5±0.5) grams were used. Before the experiment, fish stocked in a 2000 L circular fiberglass tank and acclimated to the husbandry system for two weeks. In this experiment, 6 treatments with 3 replications were considered and fishes were distributed in 18 fiberglass tanks with volume of 60 L (10 fish tank-1) and each treatment replicated in triplicate. The PP rich-diet was supplemented with different levels of OAS including sodium propionate (SP) and sodium acetate (SA) to design experimental feeds as follows: SP5 (5 g SP kg-1 diet), SP10 (10 g SP kg-1 diet), SA5 (5 g SA kg-1 diet), SA10 (10 g SA kg-1 diet) and SP+SA (5 g SP kg-1 + 5 g SA kg-1 diet). After 8 weeks of feeding, fish were anesthetized and bled with a heparinized syringe and blood was transferred into vials and centrifuged.
Results: Final weights in SP5 (14.61 g), SP10 (14.14 g) and SP+SA (14.29 g) groups were remarkably higher than the control (11.18 g). The highest and the least feed conversion ratio values were in the control (1.71) and SP5 (1.19) groups, respectively. Whole body proximate composition did not change among groups (P > 0.05). Total antioxidant capacity in the liver of fish fed on the OAS-supplemented diet also was higher than the control. Fish fed on the OAS-supplemented diets had higher pepsin, trypsin and lipase activities than the control. The insulin like growth factor-1 (IGF-1) gene expression was remarkably down-regulated in the liver of fish fed on the OAS-supplemented diets compared to the control especially in groups fed on the Na-P10 and Na-A10 diets. The greatest IGF-1 gene down-regulation level in the gut was in fish fed on the Na-P5 and Na-P10 diets. The interleukine-1β in
