An experiment was conducted to evaluate effects on growth, body composition and nutrient digestibility of addition protease and phytase to soybean meal-based diet in rainbow trout. Seven soybean meal-based diets were prepared by adding protease, phytase and mixture of both enzymes at two different levels (1 and 2 g kg −1 ) to a base diet without enzymes. Mixed enzymes (1, 2 g kg −1 ) were prepared by adding protease and phytase at the same doses (0.5 + 0.5 and 1 + 1 g kg −1 ). Diets consisted of 31% fish meal and 44% dehulled hexane extracted soybean meal. At the start of the experiment, 45 rainbow trout (initial mean body weight 88 g) were stocked into each of 21 fibre tanks. After 90 days, there were no significant differences on the growth, feed conversion ratio, digestibility of protein and lipid among the groups. Results of this study showed that the addition of protease or phytase as mix to soybean mealbased diet could not increase growth and nutrient digestibility in trout.ARTICLE HISTORY

In this study, a total of 98 lactic acid bacteria isolated from rainbow trout intestines were screened for their probiotic properties. The isolates were tested for their ability to inhibit growth of Vagococcus salmoninarum and Lactococcus garvieae. Based on in vitro antagonism, 10 isolates were selected and evaluated pathogenicity in rainbow trout. Isolates were further investigated for hydrophobicity, bile salts and acid tolerance. These isolates were able to survive low pH and high bile concentrations and showed good adherence characteristics. Isolates were characterized phenotypically, and then, 16S rRNA gene sequence analysis was used for confirmation. Selected lactis M17 2-2, respectively. Our results suggest that these strains could provide an alternative for lactococcosis control in aquaculture. K E Y W O R D Saquaculture, lactic acid bacteria, Lactococcus garvieae, probiotic, rainbow trout, Vagococcus salmoninarum

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A 12-week feeding trial was conducted with 87 g rainbow trout to evaluate the effects on growth performances, feed efficiency and nutrient digestibility of adding β-mannanase and α-galactosidase enzymes, solely or in combination. Seven diets were prepared by adding β-mannanase, α-galactosidase and mixed enzyme at two different levels (1 g/kg and 2 g/kg) to control diet (without enzyme) including soybean meal. Mixed enzymes (1 g/kg, 2 g/kg) were prepared by adding β-mannanase and α-galactosidase at the same doses (0.5+0.5 g/kg and 1+1 g/kg). At the end of the experiment, addition of β-mannanase, α-galactosidase and mixed enzyme to diet containing 44% soybean meal had no significant effects on growth performance and gain:feed (p>0.05). In addition, adding β-mannanase, α-galactosidase and mixed enzyme in different rations to trout diets had no affect on nutrient digestibility and body composition (p>0.05).

Aeromonas hydrophila is known to be causative agent of an infection named as Bacterial haemorrhagic septicaemia or red pest in freshwater fish. The aim of this study was to develop and validate the glycoprotein-based fish vaccine against Aeromonas hydrophila. For this aim, after identification and characterization of A. hydrophila isolates from fish farms, one A. hydrophila isolate was selected as vaccine strain. Antigenic glycoproteins of this vaccine strain were determined by Western blotting and glycan detection kit. The connection types of these glycoproteins were examined by glycoprotein differentiation kit. Two glycoproteins, molecular weights of 19 and 38 kDa, with SNA connection type were selected for use in vaccination trials. After their purification by SNA-specific lectin and size-exclusion chromatography, protection studies with purified proteins were performed. For challenge trials, four experimental fish groups were designated: Group I (with montanide), Group II (with montanide and ginseng), Group III [with Al(OH)3 ] and Group IV [with Al(OH)3 and ginseng]. The survival ratings of fish were determined, and protection was calculated as 21.56%, 29.41%, 69.83% and 78.88% in groups I, II, III and IV, respectively. In conclusion, A. hydrophila glycoproteins with Al(OH)3 and ginseng could be used as a safe and effective vaccine for fish.