The effects of different dietary levels of organic and inorganic selenium on some growth performance and proximate composition of juvenile rainbow trout (Oncorhynchus mykiss)

Selenium, a trace mineral complement is used as cofactor of antioxidant enzymes that protects fishes against environmental stress agents and enhances performance in fishes. In this study the different levels of organic and inorganic source of selenium were included in juvenile rainbow trout diet to evaluate feed conversion ratio (FCR), specific growth rate (SGR), weight gain percent (WG), condition factor (CF), survival rate (SR) and proximate analysis of the fillet during 60 days of the experiment. The fishes were allotted to 9 treatment groups including: Tc the fishes were fed diet without any selenium, control group; To1, To2, To3 and To4 the fishes were fed different dosages of inorganic [sic] selenium; and Ti1, Ti2, Ti3 and Ti4 those were fed different dose of inorganic Se in their diet. Results showed that To4, showed the highest level of WG from 50±2.8 to 168.54± 25.56 g in comparison to Tc (134.38± 27.26g) (p<0.05). Average initial total length of fishes (19± 1.12 centimeters) increased to 21.1± 1.12 cm in Tc and 22.46± 1.25 cm in To4 significantly (p<0.05). Among all treatments, FCR, SGR, WG, CF and SR were improved in To3 group. Also carcass protein increased in To4 (32.58±1.22%) on the contrary of Ti4 (22.43±1.51%) (p<0.05). As a general conclusion, dietary incorporation of organic selenium at 0.45 mg/kg showed satisfactory results in some growth parameters and was a useful supplement in salmonid fish diets

Effect of dietary phytase and wheat bran on some growth performances and phosphorus absorption function of common carp (Cyprinus carpio) fry

In this study, the effect of dietary phytase and wheat bran on some growth performances and phosphorus absorption function of common carp fry for 60 days was assessed. A total number of 180 common carp fry (20±1 initial weight) was randomly distributed in six experimental groups including, control group without any additive (basal diet), T1 (basal diet+2000 IU/Kg phytase), T2 (basal diet+4000 IU/Kg phytase), T3 (basal diet+20 g/Kg wheat bran), T4 (basal diet+40 g/Kg wheat bran) and T5 (basal diet+2000 IU/Kg phytase+20 g/Kg wheat bran). The highest body weight (150.02±4.76 g), specific growth rate (0.65±0.19%), and condition factor (3.20±0.26%) was observed in T5 (p<0.05). However, the lowest FCR (2.53±0.70) was seen in T5 (p<0.05). Also, the highest phosphorus concentration in the fry bones (2.54±0.003 ppm) was recorded in T5 (p<0.05). Results showed that using of 2000 IU/Kg phytase and 20 g/Kg wheat bran in the diet can improve growth indices and phosphorus absorption rate of common carp fry

Short communication: The effects of Chlorella vulgaris supplementation on growth performance, blood characteristics, and digestive enzymes in Koi (Cyprinus carpio)

Microalgae are a wide group of photosynthetic heterotrophic organisms consisting of vital amino acids, protein, minerals, vitamins, chlorophylls and some forms of antioxidants and bioactive substances (Yamaguchi, 1996; Kwak et al., 2012). According to Takeuchi et al. (2002), microalgae are valuable in aquaculture and have been utilized as live feeds for larval or juvenile crustaceans and finfish, for all bivalve mollusks including oysters, scallops, clams and mussels and as a feed for zooplankton in aquaculture. Microalgae are well provided sources of vitamins, fundamental amino acids, minerals, vital fatty acids, and carotenoid pigments for aquatic animals (Takeuchi et al., 2002). Many kinds of microalgae in feeding trials with fish increase growth (protein accretion), feed utilization, physiological activity, stress response, starvation tolerance, disease resistance, carcass quality (Mustafa and Nakagawa, 1995), carotenoid , and protein sources for shrimp (Patnaik et al., 2006; Regunathan and Wesley, 2006)

Nutritional value and heavy metal content of fishmeal from the Southwest Caspian Sea

This study aimed to evaluate some nutritional values and heavy metal contents of fishmeal produced by the commercial factories in Guilan Province, the Southwest Caspian Sea. The fishmeal samples were randomly collected from five factories producing fishmeal by Kilka (Clupeonella spp.) (units 1-4) and tuna canning offal (unit 5) as the raw materials. Proximate fish composition, amino acid contents and four heavy metal concentrations including chromium (Cr), cadmium (Cd), lead (Pb), and mercury (Hg) were measured in the fishmeal specimens. Crude protein contents were found to be in the range of 53.61-68.82% and the lowest value belonged to the unit 5. Also, the highest level of fat and ash contents were 22.49% and 18.05%, respectively (p < 0.05). The lowest essential: nonessential amino acid ratio was 0.71 in unit 5. Fishmeal specimens from unit 5 showed the highest metal concentrations with the following descending order: Cr > Cd > Pb > Hg. Results indicated that the heavy metal concentrations in the fishmeal are dependent on the source of raw materials. The heavy metal concentrations in the examined fishmeal did not exceed the permissible limits proposed by National Research Council (NRC) for animal feedstuff requirements

Impacts of extremely low-frequency electromagnetic fields (50-Hz) on growth performance and survival rate of common carp, Cyprinus carpio fingerlings

All organisms are probably exposed to different types of electromagnetic fields (EMFs). This study is an attempt to evaluate the effect of extremely low-frequency EMFs (50 Hz) on some growth parameters and survival rate of common carp fingerling. The fish (n = 120, averaged 16.76 ± 0.88 g in initial weight) was exposed to ELF-EMF at four intensities of 0.1, 0.5, 1 and 2 mT only once for 2 h and then reared for 60 days. The obtained results revealed that all growth indices were significantly (p < 0.05) improved by increasing in the EMFs intensity. Two mT treatment indicated the highest final weight (43.95 ± 0.27 g), weight gain (6.83 ± 0.10 g), weight gain rate (20.94 ± 0.13 %), daily growth rate (0.38 ± 0.00 g day-1), specific growth rate (1.26 ± 0.01 % day-1) and the lowest food conversion ratio (p < 0.05). Survival rate significantly (p < 0.05) increased in all exposed treatments compared to the control group. In conclusion, ELF-EMF can enhance the growth indices and survival rate of common carp as one of the most commercially-important cultured fish species over the world

Effects of nonylphenol on hematological parameters and immune responses in immature rainbow trout (Oncorhynchus mykiss)

This study investigated the effects of nonylphenol (NP) on hematological and immunological parameters in both male and female rainbow trout (Oncorhynchus mykiss). Fish were randomly distributed into six groups and administered with NP (10, 50 and 100 μg g-1 week-1 BW) and a single dose of 17-β estradiol (E2; 2 μg g-1 week-1 BW, positive control). The solvent controls received ethanol and coconut oil as a vehicle, while the controls were not injected. Red blood cells (RBCs) count, hematocrit (Hct), hemoglobin (Hb), white blood cells (WBCs), and lymphocytes demonstrated a NP dose-dependent decrease, whereas mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), monocytes, and neutrophils showed an increasing trend in both male and female fish 21 days post-treatment. Also, RBCs, Hb, MCHC, WBCs, and lymphocytes were significantly reduced (p<0.05) in E2 treated fish. Lysozyme, complement components (C3 and C4) and immunoglobulin M (IgM) were increased in fish sera subjected to 10 and 50 μg g-1 NP, while these decreased in groups administered with 100 μg g-1 NP and 2 μg g-1 E2. Except for C4 level at 10 μg g-1 NP, no significant differences were observed in hematological and immunological parameters of male and female in each treatment. Overall, a frequent exposure to NP could lead to adverse effects on fish immune-physiological functions which may cause serious ecological threats of fish natural population sustainability

Job Stress among Iranian Nurses: A Meta-Analysis

Background: Job stress is one of the most important factors in reducing the organizational productivity. Objective: This meta-analysis aimed to determine the prevalence of job stress among nurses in Iran. Methods: All articles published on the prevalence of job stress among Iranian nurses from January 1, 2004, to April 31, 2020, were searched in six databases. The reference lists of the articles were also checked for additional relevant studies. Finally, 25 articles were analyzed through Comprehensive Meta-Analysis software. Heterogeneity of studies was checked using the I2index, Q-test and the possibility of publication bias by the Egger test. Metaregression was performed to assess the variables suspected to affect the heterogeneity at a significance level of 0.05. The outcomes of the study were combined using the random-effects model. Results: The overall prevalence of job stress in Iranian nurses was 37.5 (95 confidence interval CI: 28.5, 47.4). The highest prevalence was 96.4% in Tehran city in 2016 (95% CI: 90.3, 98.7), and the lowest prevalence was 2% in Kashan city in 2011 (95% CI: 0.7, 5.3). A significant correlation was observed between the prevalence of job stress and year (P = 0.0001), mean age (P = 0.002), and sample size (P &lt; 0.0001). Conclusion: Job stress affects over a third of Iranian nurses. Health-care policy-makers and managers should decrease this stress by adopting appropriate strategies such as increasing welfare facilities, reconsidering job descriptions for different levels of nursing, providing support, increasing nurses' involvement in the decision-making process, improving communication between managers and nurses, and teaching problem-solving skills to them. © 2021 Wolters Kluwer Medknow Publications. All rights reserved

Effects of olive pomace on growth performance, digestibility, body composition and fatty acid profile in yearling Siberian sturgeon, Acipenser baerii (Brandt 1896)

Replacement of olive pomace (OP) with wheat flour in diet was studied in diet of yearling Siberian sturgeon (Acipenser baerii). Fish (165 ± 6.8 g) were randomly allocated to 15 fibreglass tanks (15 fish/tank, in triplicate). Fish were assigned to one of five dietary treatments at 19.1 ± 1.5°C for 8 weeks: control diet (crude protein and crude lipid at 514.6 and 188 g/kg, respectively) and four experimental diets with 20, 50, 75 and 100 g/kg OP to replace wheat flour in the experimental diets. No significant difference was observed in the final weight, feed conversion ratio, specific growth rate, hepatosomatic index, viscera‐somatic index and survival rate among the treatments (p > 0.05). No change was seen in digestibility of protein and lipid in diets containing 20 g/kg and 50 g/kg OP compared to control group, while these values decreased with increasing in OP above 50 g/kg. Digestibility of dry matter and gross energy among the treatments demonstrated no significant difference (p > 0.05). Polyunsaturated fatty acids, especially C22:6n3 (DHA), in the muscle of the fish fed 75 g/kg and 100 g/kg OP in diets were significantly higher than control group (p < 0.05). These data show that OP could be recommended as a substitute for wheat flour in diet of S. sturgeon but its utilization for other species warranted future works

Immuno-physiological and antioxidant responses of Siberian sturgeon (Acipenser baerii) fed with different levels of olive pomace

Nowadays, use of the natural plant derivatives as an immunostimulant in aquaculture is becoming more useful than antibiotics which are destructive to target animals, consumers, and the environment. The present study aimed to evaluate the efficacy of dietary substitution of wheat flour at 2, 5, 7.5, and 10% of olive pomace (OP2, OP5, OP7.5, and OP10) in some immune-physiological and antioxidant variables of yearling Siberian sturgeon (Acipenser baerii) weighing 165 ± 6.8 g at 19.1 ± 1.52 °C for 56 days. Fifteen fish per tank were randomly accommodated in triplicates per treatment and the control group was also included. No significant difference was seen in hematological indices including red blood cells (RBS) and immunocompetent cell population sizes among the treated groups (P > 0.05). Also, malondialdehyde (MDA) activity and superoxide dismutase (SOD) in serum remained unaffected in different treatments (P > 0.05). Total protein (TP), high-density lipoprotein (HDL), catalase (CT), and lysozyme were affected by dietary OP levels (P < 0.05), and the highest value was observed at the OP5 diet, but no influence was seen in serum IgM by OP. These data show that application of olive pomace as a partial substitute of wheat flour in the diet of Siberian sturgeon is feasible with stimulatory and antioxidant functions