Assessment of digestive enzymes activity during the fry development of rainbow trout, Oncorhynchus mykiss: from hatching to primary stages after yolk sac absorption

The aim of this study was to determine the activity of digestive enzymes during the fry development of Rainbow trout ( Oncorhynchus mykiss ), which has a remarkable role in food digestion and absorption in the first feeding. The assessment of digestive enzymes activity of gastric (pepsin), pancreatic (trypsin, chymotrypsin, α-amylase and lipase) and intestinal (alkaline phosphatase) revealed that enzymes were available on the first day after hatching (DAH) but their activity showed no significant difference from hatching to day 12 (P > 0.05). An increased activity was seen between 12 and 18 DAH and this activity was significantly higher than the first 12 days (P 0.05). These results could be used as a basis for formulating a suitable feeding and also selecting the best time for starting the feeding so that optimum nutritional values and cost-effectiveness are achieved

In vitro inhibition of growth in Saprolegnia sp. isolated from the eggs of Persian sturgeon Acipenser persicus (Pisces: Acipenseriformes) by Pseudomonas aeroginosa (PTCC:1430)

Saprolegnia is one of the most important agents decreasing the eggs survival rate in sturgeon hatcheries.There are some chemical substances for controlling the fungal infection of eggs. In this study, an attempt was made to introduce a germ negative bacterium, Pseudomonas aeroginosa (PTCC1430)(Persian Type Culture Collection) as a biocontrolling agent of water mold. Saprolegnia was isolated from the eggs of some infected Persian sturgeon, Acipenser persicus in a sturgeon hatchery and then was purified. P.aeroginosa was cultured in Potato dextrose Agar (PDB) media and then was prepared in 5 concentrations (103,104,105,106and107cfu.ml-1) while challenging with fungi in petri dishes under laboratory conditions.The results showed that by increasing the concentration of the bacteria in plates, hyphal growth of the fungi was reduced. The highest concentration of P. aeroginosa concentration (107) roughly stopped the -fungi growth and the Minimum Inhibitory Concentration (MIC) was 104cfu.m-l. Results in this study implied the potential of P. aeroginosa (PTCC1430) as a biological agent in controlling saprolegniosis

Changes in biochemical and physiological responses of common carp, Cyprinus carpio L. after long-term exposure to Pb (II)

In this study, the chronic toxic effects of Pb (II) on common carp, Cyprius carpio were investigated using several biomarkers at different levels of biological functions for assessing changes in ecosystem quality. In a bioassay,common carp juveniles were individually exposed to different dose of heavy metal, Pb II (0, 0.45, 0.89, 1.34 mg.l-1) for 28 days. Morphological indices such as hepatosomatic index, condition factor and lipid peroxidation (LPO) level and also the activities of superoxide dismutase (SOD) and catalase (CAT) were measured. These results indicated that there was significant lower condition factor in fish exposed to the highest concentration of Pb (p<0.05). The activity of hepatic antioxidant enzymes (SOD & CAT) and LPO level was significantly elevated after long-term exposure to higher concentration of Pb (p<0.05). Briefly, our findings suggested that common carp exposed to lead, develop oxidative stress, hence long-term exposure to higher concentrations of Pb could seriously affect the health status of fish

Infection of three-spined stickleback Gasterosteus aculeatus (L.) with Corynosoma strumosum in Gomishan Lagoon

To study infection of Three-Spined Stickleback, Gasterosteus aculeatus (14 we sampled 530 specimens of the fish during November 2000 till October 2001 in Gomishan Lagoon, southeast of Caspian Sea. The fish were collected using beach seines with 3mm mesh size. The specimens were transferred to lab fresh or fixed in 10% formalin and examined by standard methods. Numbers of parasites for each male or female were recorded and intensity, frequency and prevalence of the parasite for each month and sex were calculated. Maximum infection occurred in late winter and early spring and the maximum number of parasites was 82, obtained from a female fish in early spring

Survey on parasite infection of two years old carp bream, Abramis brama, to Ligula intestinalis in Alagol lake and Gorganroud (Golestan dam) - Golestan province

To evaluate the infection of carp bream (Abramis brama) with ligula intestinalis in Golestan province, 92 fish samples from two regions: Gorganroud (61 samples) and Alagol lakes (31 samples) were investigated. According to the result in the present study, the prevalence of ligula intestinalis plerocercoid infestation in carp bream from Alagol Lake for male, female and overall (male and female) were 5.88%, 7.14% and 6.45%, respectively, also in the Gorganroud river for male, female and overall (male and female) were recorded as 22.22%, 26.47%, and 24.59%, respectively. Based on the statistical analysis, the prevalence of this parasite in fish specimens from the Gorganroud was recorded significantly higher than Alagol lake`s specimens. In this study, the mean intensity ± SD of parasite infestation for carp beam in Alagol Lakes and Gorganroud were recorded as 2.5 ± 2.1 and 2.00 ± 1.25, respectively. There was no significant difference in mean intensity of ligula intestinalis infection between two mentioned regions (P<0.05). The length of isolated and number of isolated parasites for each infected fish was different between 6 -64 cm and 1-5 numbers respectively. Totally, mean prevalence and intensity of ligula intestinalis infection for both regions in Golestan province were recorded as: 18.48 % and 2.05 ± 1.25 number (per infected fish) respectively. There was no significant difference between male and female for prevalence and intensity of parasite infection in this study (P<0.05)

The effects of different concentrations of probiotic Saccharomyces cerevisia on growth performance and survival rate of rainbow trout (Oncorhynchus mykiss), fry and resistance against salinity

In the present study, a yeast strain Saccharomyces cerevisia var. elipsoidous, acting as probiotic, was administered to rainbow trout (Oncorhynchus mykiss Walbaum, 1792) fry during a period of 21 days and the effects of the yeast on improvement of growth and resistance against environmental stress were evaluated with respect to fish fed on yeast free feed (control group). The control treatment consisted of a standard commercial diet, and the treatments consisted of the control diet supplemented with 0, 1, 5 and 10% yeast (w/w). The results demonstrate the beneficial effects of probiotics on the characteristics of rainbow trout, as the Specific Growth Ratio (SGR), body weight gain (%BWG) and protein conversion ratio (PER) in 5% yeast-fed fish were significantly (P&lt;0.05) enhanced by probiotic administration. On the contrary, no effect on the fry growth performance, mortality, condition factor (CF), food conversion ratio (FCR) and histological assessment was shown. A significant (P&lt;0.05) increase in lipid content of the carcass was detected in diets with probiotic compareD to 0% and the control treatments. Ash and protein contents of the carcass increased and decreased with an increase in yeast amount, respectively. Challenge with different levels of salinity (10 and 15 ppt) after 24 h revealed 100% survival in treatments containing yeast as probiotic, and difference with control group was significant (p&lt;0.05) indicating that S. cerevisia could enhance the resistance against salinity stress. Addition of yeast in concentration of 5% to the diet is recommended during the early period of rainbow trout fry farming to achieve the best results on growth performance and feed efficiency.Keywords: Saccharomyces cerevisia var. elipsoidous, Oncorhynchus mykiss, probiotic, survival and growth rate, carcass qualityAfrican Journal of Biotechnology, Vol. 13(10), pp. 1160-1168, 5 March, 201