JOURNAL OF FISHERIES SCIENCE AND TECHNOLOGY (JFST)
Year:2014 | Volume:3 | Issue:1|Papers Count:7

The probiotic effects of Saccharomyces cerevisiae and Aspergillus niger on the feeding efficiency, body composition, ammonia excretion, blood serum enzymes and the intestinal microbiota of juvenile beluga, Huso huso was investigated. The fish (31.8±2.81g) were randomly allocated into 12 oval tanks at a density of 30 individuals per tank with three replicates for each treatment,. The fish were fed either a basal diet (as control) or the diet supplemented with S. cerevisiae and A. niger (2×106, 4×106 and 6×106 cells g-1) for 8 weeks. The results indicated that the probiotic supplemented diet at 6×106 (cells g-1) significantly improved FCR and other nutritional indicators compared to the control treatment (p<0.05). Significant improvements (p<0.05) were also observed in ammonia excretion and blood serum enzymes between treatments. Total viable fungus and Lactobacillus spp. count were significantly improved in treatment compared to control (p<0.05). These results indicated that S. cerevisiae and A. niger improved feeding performance and blood serum enzymes of beluga.

The effect of six diets including Scenedesmus quadricauda), manure (cattle+poultry, 1: 1 ratio), vegetable (spinach+parsely+coriander, 1: 1: 1 ratio), algae+soil, vegetable+soil, and manure+soil were examined on culture of freshwater copepod, Acanthocyclops robustus, under the experimental conditions of 23±1oC, 12 hours dark: 12 hours light photoperiod, and light intensity of 60 μmol photons/m2/s. The maximum population density (1282.6±163.7 individuals/L), maximum specific growth rate (SGR) (0.17±0.0 /day) and minimum doubling time (Dt) (4.0±0.1 days) were obtained when A. robustus fed on algae+soil. The nauplii production was 727.3±42.4 (±SE), 272.0±23.5, 267.6±17.7, 147.0±18.2, 33.6±3.8 and 25.0±7.1 ind./L and copepodit production was 311.3±26.8, 124.3±11.1, 183.0±13.0, 59.0±7.1, 14.3±8.1, and 17.6±3.6 ind./L in algae, algae+soil, vegetable, vegetable+soil, manure+soil, and manure, respectively. Correspondingly, the adult production was 208.5±26.8, 51.6±16.5, 192.7±23.7, 91.7±28.4, 8.7±5.4 and 8.7±3.6 ind./L, respectively. The maximum body length (663.8±29.1 mm) and width (526.2±23.7 mm) of A. robustus were recorded when fed with vegetable+soil and vegetable, respectively. The number of nauplii, copepodit, adults, length and width were significantly correlated with EC, BOD and COD. According to results, the A. robustus has suitable potential culture on algal and non-algal diets based on production, growth, body size, BOD and COD, but the better performance obtain on algae+soil and vegetable.

The effect of an imported and an indigenous probiotics on growth, feeding parameters and survival of whiteleg shrimp (Litopenaeus vannamei) postlarvae (50±6.54 mg) was investigated during 60 days feeding trial. The shrimp was fed three times daily at 7 percent of biomass with three feeds supplemented with probiotics (an imported and an indigenous ones, and an equal amount of both), plus a blank feed as control. Probiotic supplemented feed brought about a higher final weight and final length, specific growth rate, better feed conversion ratio and a higher resistance to stress (p<0.05), the highest of which was observed in the treatment containing imported probiotic. This experiment indicated that the feed supplemented with Bacillus probiotic can increase the growth and feeding indices and stress tolerance in L. vannamei larvae.

The effect of edible chitosan and chitosan-gelatin coating on the quality of fish finger from silver carp during refrigeration was assessed. Fish fingers were immersed separately in coating solutions of chitosan 1% and chitosan 1%-gelatin 4%, packed and stored in refrigerator (4±1oC) for 30 days, then their chemical (TVB-N, PV, TBA) and microbiological characteristics (TVC and PTC) were analysed. Total volatile basic nitrogen value of coated sample with chitosan was lowest while there was no significant difference between the thiobarbituric acid value of coated treatments (p<0.05). Among the coated samples, chitosan coating effectively reduced the total viable count (TVC) and psychrotrophic count (PTC). This reduction was 3.2 and 2.6 log10 cfu/g for TVC and PTC at 12 day, respectively, in comparison with control. Thus it can be considered that fish fingers coated with chitosan coating solution was more effective than chitosan-gelatin coating and uncoated samples and increased the shelf life of fish fingers for 18 days.

The effect of cadmium on hematological and biochemical indices of silver carp (Hypophthalmichthys molitrix) exposed to subacute (0.65ppm) and acute (3.25ppm) concentrations for 96-h test period was assessed. The results showed that Hb, Hct, RBC and MCV significantly decreased in low concentration of cadmium (p<0.05), while MCH, MCHC, WBC, glucose and cortisol were significantly (p<0.05) higher than control group in both low and high concentrations. This study reveals that some hematological and biochemical indices of silver carp, such as cortisol, can be used as suitable biomarkers in tracing Cd2+contamination within water bodies.

A 12-week feeding trial was carried out in 500 L fiberglass tanks to evaluate the effect of dietary choline at 0, 2, 4, and 8 g kg-1 levels on growth rate, body composition and total liver lipid of juvenile Acipenser baerii (37.67±0.67 g). A semi purified basal diet was formulated using vitamin free casein and wheat gluten as a protein source, a mixture of animal and plant oils as a lipid source and dextrin as a carbohydrate source. Four isonitrogenous (40% protein) and isoenergetic (18 MJ kg-1) diets were prepared and fed to the fish three times daily to apparent satiation. Weight gain, feed conversion ratio (FCR), specific growth rate (SGR) and protein efficiency ratio (PER) were significantly affected by dietary choline (p<0.05). The best growth performance was observed in fish fed diets containing 2 and 8 g kg-1 choline (p<0.05). Fish fed with 2 and 4 g kg-1 choline showed higher lipid content compared with the control diet (p<0.05), but not significantly different in body protein (p>0.05). Total lipid of liver and plasma, plasma cholesterol, triglyceride and phospholipids levels showed an increasing trend with increasing levels of dietary choline, but not significantly different among treatments (p>0.05). Based on the results, we recommend adding a 1.5 gkg-1 choline to commercial diet of juvenile Acipenser baerii.

Length-weight relationships and fecundity of 93 individual female Acipenser persicus broodstocks were investigated. The specimens were caught during 2001- 2005 from Golestan, Mazandaran and Guilan provinces along the southern coast of the Caspian Sea. Total length and weight of each fish was measured to the nearest 1cm and 100 g, respectively. Age determination was carried out by using transects of the first ray of pectoral fin. The absolute fecundity was assessed by egg count per weight unit of all eggs existed in the body. The specimens were from 13 to 20 years old, of which the 16 years old had the highest proportion with 23.7%. Range of total length and weight were 132.5 to 211 cm and 14 to 42 kg, respectively. Mean absolute fecundity was estimated 267810±92570. Total length, weight and absolute fecundity of fish increased with age in all cases, showed a significant positive correlation (p<0.01). The slope of the length-weight relationship (b) was equal to 2.745 and isometric growth pattern was determined in this species.