Effects of dietary Propionic acid on growth performance and resistance to salinity stress in Caspian roach (Rutilus caspicus)

In the present study the effects of complementary propionic acid in Caspian roach (Rutilus caspicus) diet on growth indices and stress parameters against salinity exposure have been studied. In this regard, 3 treatment and one control groups considered. Therefore 180 fingerling fish with average weight of 10.78 ± 1.78 were divided in 12 fiberglass tanks with dimensions of 1.5 × 1.5 m and of 60 liters volumes (15 pieces per reservoir). Fish were fed with different levels of propionic acid in diet including 0 (for control group), 0.5%, 1% and 2% in three replicates for each group during 2 months. After 60 days all fish were exposed to 10 ppt salinity solution as sub lethal stress for 12 hours. Then for determination of glucose and cortisol levels (as stress markers) blood sampling had done for 6 times including: before salinity stress, immediately after salinity stress, 12 h, 24 h , 48 h and 72 h post salinity stress. according to the results in all treatment groups that fed with different levels of supplementary propionic acid growth indices including: final weight, body weight gain, specific growth rate and percentage of body weight gain in all were significantly lower than control group (p