Investigation on replacement of fish oil by vegetable oils (rice bran, soybean and linseed) in diet of rainbow trout (Oncorhynchus mykiss)

The aim of the present study was to determine the impact of replacing the fish oil by alternative lipid sources in diets for rainbow trout (Oncorhynchus mykiss) on growth, fatty acid profiles of muscle. Five isonitrogenous and isoenergetic semipurified diets were formulated containing 100% rice bran oil (RBO), 100% linseed oil (LO), 100% Soybean oil (SO) and a 1:1:1:1 rice bran, linseed, soybean and fish oil mixture (MX) were compared to a pure fish oil (FO) diet. The diets were fed to apparent satiation twice a day to triplicate groups of 30 rainbow trout with an initial weight of 90g for 15 weeks at 12°C.At the end of the experiment, fillet samples were collected from fish for the measurement of fatty acid profile and fillet composition. Fish fed the FO diet had the highest weight gain over the experimental period (280.28 g), However no differences in growth rate and CF were observed across diet groups. Feed conversion ratios (FCR) ranged from 1.12 to 1.24. Significant difference in FCR was found in the group fed an FO diet. The fillet lipid concentrations and fatty acid composition of the fish were significantly affected by the experimental diets. Fish fed the FO diet contained significantly lower lipid levels (20.18%) than those fed the 4 other diets. The highest level of n-3 PUFA concentrations were recorded in fish fed the LO diet (21.8) with significant difference than other diets and the lowest were in those fed the RBO diet (7.84). Fish fed the SO diet contained significantly higher level of n-6 PUFA concentrations (31.72) than other diets and the lowest were in those fed the FO diet (19.15). Fish on the FO diet had a significantly greater percentage of DHA (10.10%) in muscle tissue compared with fish on all other diets and the lowest was in those fed the RBO diet (2.81%). However, the highest level of eicosapentaenoic acid (EPA) concentrations was recorded in fish fed the SO diet (1.84%) and the lowest in those fed the diet (0.67%). This study showed considerable reductions (about 3-fold) in the n-3/n-6 ratio when FO in the fish diet was replaced by rice bran and soybean oils, which may be extremely negative from a nutritional point of view. In other hand linseed oil had the highest n-3/n-6 ratio (0.91) that was comparable with fish oil n- 3/n-6 ratio (0.89). The results in this study imply that an appropriate mix of vegetable oils and FO can replace the sole use of FO in fish feeds

The control of recovery process with clove tree (Eugenia caryophyllata) in rainbow trout (Oncorhynchus mykiss)

In order to investigate the effect of different temperature of anesthetic (clove tree) and recover (anesthetic-free water) solutions on recovery process, The anesthetic induction times and recovery times of 540 fingerlings of rainbow trout (Oncorhynchus mykiss) weighing 3.2 ± 0.2 g in anesthesia/ recovery solutions with cross-combined of temperature of 5,11 and 17 °C as experimental treatments (9 treatments) were compared. The anesthesia was induced by170 ppm of aqueous clove (Eugenia caryophyllata) solution. Results showed that both induction and recovery times were adversely temperature-dependent. Recovery times of treatments, related to temperature of anesthetic solutions and their temperature, were significantly different (P < 0.05). Our results indicated that mean recovery time (three temperature treatments) of the fish exposed to the lower temperature anesthetic solutions generally decreased opposing with higher anesthetic solutions. The lowest recovery time (61±11.1 seconds) in17°C anesthetic-free water occurred in fishes induced to 5°C anesthetic solution. In contrast, the highest recovery time (523±154 seconds) in 5°C water happened in fishes induced to 17°C anesthetic solution. Warm and cold thermal difference in anesthetic and recover solutions could extend recovery time 1 up to 8 minutes. Regarding to aim and demanded time, by selected favorite temperatures can control anesthesia/or recovery time in order to prevent the use of drug over-dosing

Genetic variations of Iranian and French stocks of rainbow trout (Oncorhynchus mykiss)

Rainbow trout, Oncorhynchus mykiss is the most important cold water farmed fish as a nonindigenous species in Iran. Eyed eggs have been imported from different countries to Iran. In this study, genetic diversity of 50 fish (male and female) from Iranian generation and 24 fish from French generation were evaluated. Six microsatellite markers including OMM1019 ،OMM1036 ،OMM1307 ، OmyFGT5TU ،Omy77DU and Omy207UoG were applied. Average number of observed alleles in the Iranian and the French stocks were 6.68 and 6.83, respectively. Average number of effective alleles in the Iranian and French stocks were 3.13 and 3.45, respectively. Mean expected and observed heterozygosis was 0.68, 0.53 and 0.71, 0.61 in Iranian and French stocks, respectively. The results showed significant deviation from Hardy-Weinberg equilibrium at the most of loci × stock. Fixation index Fst calculated based on allelic frequency between two stocks was 0.058 with significant difference between 2 stocks. The results of this study showed insignificant genetic differentiation based on six microsatellite loci

A case report of Enteritis Redmouth Disease in cultured rainbow trout (Oncorhynchus mykiss) in Kohkyloyeh va Boyerahmad Province in Iran

An unknown mortality was occurred in some ponds of a farm in an area of Kohgiloyeh-&- Boyerahmad province. Three ponds showed the highest mortality rate, about 5 to 20 dead fish were reported daily for 45 days. Afflicted fish have darkening in the skin and swimming near surface or at the floor of pond and swam unmatched with flock. Some fish showed hemorrhages around and within the oral cavity and exophthalmia occasionally. About 45 moribund rainbow trout were sampled for dissection and bacteriological examination. Kidney, liver and spleen of the fishes were examined for the detection and identification of bacteria causative agent of disease in rainbow trout. They cultivated aseptically on different media (Blood Agar, Tryptic soy Agar, TCBS Agar and MacConkey Agar). All fish have been infected and suffered septicemia. A type of gram's negative bacteria was responsible of infection and mix infection was not confirmed. The bacterium was being able to grow on Mac Conkey agar. It was a bacterium very similar with Yersinia ruckeri which induced infection. Detection was based on clinical finding and bacteriological laboratory results so using of some confirmation methods such as FAT or PCR would be recommended strongly

A Study on necessary infrastructures used for breeding trout in Yasoj region

Rainbow trout is the main cultural species of coldwater fishes in iran. Often, aquaculturists intend to breeding in order to production of lines with higher growth rate potential and disease resistant. Nevertheless in the country, no trout breeding programs, has been performed yet and most of the farms focused on the cultivation of the first(unbred) race. While European countries progressed in trout breeding techniques and production lines with higher growth through genetic manipulation (chromosomal number and type changes of fish) and/or selection and their fish products derived from this technology, including eyed eggs and so on have sold to other regions of the world(eg: Iran). In this study, some biological parameters including survival, growth, feed conversion ratio (FCR.) and chromosomal number of two juvenile groups from imported( group 1) and native(group 2) eyed fish eggs were compared. For chromosomal investigation, blood smear test and flow cytometry were performed. sults showed a significant difference (P≤5%) in growth rate of native fishes and French group Native fish feed conversion ratio (0.9) was significantly difference (P≤5%) from that of French fishes (1.15). Chromosomal analysis showed no difference in chromosome number in treatments and two fish groups were 2n chromosome. Based on the results, the fishes of group 1 had faster grow potential and gain weight in less time than that of group 2 and this has been achieved to go through the process of selection and feminization without any change in number of ploidy. Whereas the ability of native fishes in food efficiency ( lower FCR.) was better. However, the reduction of rearing period is the benefit and preference of cultivation of imported or origionally foreign

Production of monosex female population of rainbow trout by use of 17-B estradiol as direct method

In many species of finfish, females exhibit higher growth rates than males and achieve larger sizes. In addition, in some species, males mature before reaching marketable size. Therefore, there is great interest from the fish farmers to produce all-female stocks. In this project tried to reversing the sex of rainbow trout larvae by 17 estradiol and direct method, further more finding the optimum dose of this natural estrogen for endocrine sex reversion of Rainbow trout (O. mykiss). Four experimental treatments were designed with doses of 10, 20, 30 and 40 mg/kgf. Trout which treated with 40 mg/kgf yielded 96% female and greatest growth

Estimation of hormone residuals (B-Estradiole) in rainbow trout

Residual level of 17- Beta Stradiol and progesterone hormones in rainbow trout fish plasma were measured during different period using RIA method. Blood sampling from abdominal aorta were taken from 70 individual of female fishes (100±11 g) which had been exposed to hormone at 0.5, 1,2,4,8,12,24 and 168 h (7 groups) compared with control group which was not exposed to this hormone. Results showed that plasma hormones measurement in different fish groups after exposing had significant differences (P<0.01) and the highest and lowest 17-Beta Stradiol hormone residue were observed in fishes that exposed 0.5h and 168h to hormone respectively (121±9 ng. ml^-1 and 3±0.9 ng. ml^-1) but there is no any differences between fishes exposed 168h to hormone and control group. Also the highest progesterone hormone level were measured in fishes 0.5 an 1h exposed and the lowest one was in fishes 168 h exposed. The range of progesterone hormone were between 0.3 to 1.1 ng .ml^-1 and significant increasing of this hormone levels were obtained in fishes exposed to hormone 4 to 24h (P<0.01). As consequence these hormone can not residue in fishes for a long time and maximum after one week the levels back to the normal

The study on culture of rainbow trout (Oncorhynchus mykiss) by new design of foster-lucas ponds

Intensive culture of rainbow trout, usually done using several different methods. The objective of this study was to compare fish performance and welfare in a new design of Foster-lucas ponds (FLP) and a raceway ponds (RP) under field conditions. Currennt study was designed in two treatment with three repeats. Each pond was randomly stocked by rainbow trout fish with initial average weight of approximately 51±5 g. stocking density was 120n/m3 during study. After 10 months of trial, fish fed diets with commercial diet (Chineh Company). Feeding operation conducted according to the manuals by consideration of water temperature, fish weight and biomass. During the 10 months experiment, the fish survival rate was high (97.39 and 98.05%). No significant differences in growth parameters were observed between RP and FLP, but in all parameters FLP was higher than RP Final weight was 0.99% higher in FLP than in RP. Water quality factors (Dissolved oxygen, PH) was better in FLP. The results confirm that when water quality is maintained in safe level ranges, growth rate of rainbow trout attained in FLS are comparable to those in RP

Investigation of chromosome and ploidy levels of rainbow trout produced from imported eyed eggs

Rainbow trout is the main cultural species of coldwater fishes in iran. Often, aquaculturists intend to breeding in order to production of lines with higher growth rate potential and disease resistant. Nevertheless in the country, no trout breeding programs, has been performed yet and most of the farms focused on the cultivation of the first (unbred) race. While European countries progressed in trout breeding techniques and production lines with higher growth through genetic manipulation (chromosomal number and type changes of fish) and/or selection and their fish products derived from this technology, including eyed eggs and so on have sold to other regions of the world (eg: Iran). In this study, some biological parameters including survival, growth, feed conversion ratio (FCR.) and chromosomal number of two juvenile groups from imported( group 1) and native(group 2) eyed fish eggs were compared. For chromosomal investigation, blood smear test and flow cytometry were performed. sults showed a significant difference (P≤5%) in growth rate of native fishes and French group Native fish feed conversion ratio (0.9) was significantly difference (P≤5%) from that of French fishes (1.15). Chromosomal analysis showed no difference in chromosome number in treatments and two fish groups were 2n chromosome. Based on the results, the fishes of group 1 had faster grow potential and gain weight in less time than that of group 2 and this has been achieved to go through the process of selection and feminization without any change in number of ploidy. Whereas the ability of native fishes in food efficiency ( lower FCR.) was better. However, the reduction of rearing period is the benefit and preference of cultivation of imported or origionally foreign