Автор неизвестен - Krmulture in iran - страница 31
Dietary carbohydrate level (%)
0.05 ± 0.005 c 0.002 ± 0.001 b 6.03 ± 0.46 c
0.09 ± 0.006 c
0.005 ± 0.001 b
7.42 ± 0.39 c
0.07 ± 0.002 c
0.007 ± 0.003 b 7.53 ± 1.05 c 30
0.16 ± 0.02 b
0.007 ± 0.004 b 42.96 ± 2.02 b 35
0.78 ± 0.01a
0.036 ± 0.005 a 52.19 ± 3.66 a
The results showed that growth rate is affected by different levels of carbohydrate and the rise from 15 to 35% improves the growth performance which was similar to some species such as walking catfish Clarias batrachus (Erfanullah and Jefri, 1995) and common carp Cyprinus carpio (Satoh, 1991), but it was lower than in herbivorous fish such as grass carp Ctenopharyngodon idella (Line, 1991). Better utilization of carbohydrate by fish may be related to different in the nature of their natural diet. Herbivore and omnivore fish compared with carnivores are able to better carbohydrates digestion and absorption (Cowey and Sargent, 1979). Increasing the dietary carbohydrate level at the optimum level is caused to reduced catabolism of other nutrients such as protein and lipid for energy and intermediate metabolism proved for synthesis of biologically important compounds (Wilson, 1994; Mingchun et al., 2011). In the present study, with increase the carbohydrate level, the enzymatic activity of trypsin increased that was similar with results for tambaqui (Colossoma macropmum) and also Dentx (Dentex dentex) which fed with different levels of carbohydrate (Correa et al., 2006; Amalia Perez et al., 2009). The highest trypsin activity was observed in fish fed high level of carbohydrate. The results suggest that the enzymatic capacity of fish can be improved by the food that stimulates enzyme secretion. The highest amount of trypsin enzyme activity was 0.78 ± 0.03 U/mg protein that have been observed in the fingerlings fed high carbohydrate level. This value is greater than the value reported for tilapia (Oreochromis mossambicus) and Chinook salmon (Oncorhynchus
tshawytscha) that was 0.17 and 0.07 U/mg protein, respectably (Kurtovic et al., 2006). This confirms that cyprinid trypsins may have a higher affinity than those of fish with stomach which would enhance the digestibility of protein as an adaptation to low protein diet. Although the effect of diet composition on lipase activity has been less investigated, most of the studies have explained that high fat content of the diet causes the higher lipase activity (De Almeida et al., 2006; Mohantaet al., 2008). In our study, an increase in carbohydrates has increased the activity of lipase and the same results were obtained for Dentx and common carp (Keshavanath et al., 2002; Perez et al., 2005). High carbohydrate level affects the ability of digestion and absorption of dietary fat and similar results were also observed in grass carp (Tian et al., 2011). The carbohydrates in food stimulates the activity of lipidogenesis enzymes in tissues of the body and also in pancreas and the higher carbohydrate levels increase the activity of these enzymes (Wilson, 1994; Dias et al, 1997; Hemre et al., 1998). In the present study, increased carbohydrate level has increased the levels of a-amylase activity. Increased starch in the diet of many fishes including common carp, tilapia and juveniles cobia has raised a-amylase activity (Nagase, 1964; Kawai and Ikeda, 1972; Mukhopadhyay, 1977; Migchun et al., 2011). This confirms that a-amylase activity in the digestive system of fish is related to the level of dietary carbohydrate (De Silva and Anderson, 1995). Therefore, increased level of carbohydrate increases the level of a-amylase activity.
To conclude these results indicate that the diet containing 35% carbohydrate had the highest growth rate compared to other treatments. Results have shown that carbohydrate can be a useful and sustainable energy source for Kutum.
Arockiaraj, A.J., Haniffa, M.A., Seetharaman, S. and Appelbaum, S. 2008. Utilization of various dietary carbohydrate levels by the freshwater catfish (Mystus montanus) (Jerdon). Turkish Journal of Fisheries and Aquatic Sciences, 8: 31-35.
Bradford, M.M. 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical
Biochemestry, 72: 248-254.
Correa, C.F., Aguiar, L.H., Lundstedt, L.M. and Moraes, G. 2006. Responses of digestive enzymes of tambaqui (Colossoma macropomum) to dietary cornstarch changes and metabolic inferences. Comparative Biochemistry and Physiology, Part A, 147: 857-862.
Dorafshan, S. and Peykan Heyrati, F. 2006. Spawning induction in kutum (Rutilus frisii kutum) (Kamenskii, 1901) using carp pituitary extarct or GnRH analogue combined metocloperamid. Aquacalture Research, 37: 751-755.
Erlanger, B., Kokowsky, N. and Cohen, W. 1961. The preparation and properties of two new chromogenic substrates of trypsin. Archive Biochemistry and Biophysics, 95:
Kurtovic, I., Marshall, S.N. and Simpson, B.K. 2006. Isolation and characterization of a trypsin fraction from the pyloric ceca of chinook salmon (Oncorhynchus tshawytscha). Comparative Biochemstry and Physiology, Part B, 143: 432^440.
Mingchun, R., Qinghui, A., Kangsen, M., Hongming, M. and Xiaojie W. 2011. Effect of dietary carbohydrate level on growth performance, body composition, apparent digestibility coefficient and digestive enzyme activities of juvenile cobia, (Rachycentron canadum). Aquaculture Research, 42: 1467-1475.
Iijima, N., Tanaka, S. and Ota, Y. 1998. Purification and characterization of bile salt-activated lipase from the hepatopancreas of red sea bream (Pagrus major). Fish physiology and Biochemistry, 18: 59-69.
Wilson, R.P. 1994. Utilizition of dietary carbohydrate by fish. Aquaculture, 124: 67-80.
Effect of Saccharomyces cerevisiae and Lactobacillus casei on the growth, survival and immune response in rainbow trout (Oncorhynchus mykiss)
Maria Mohseni1*, Saeid Meshkini2, Amir Tukmechi3 and Reza Jalili1
1 Department of Fisheries, Faculty of Natural Resources, Urmia University, Iran
2 Department of Food Hygienic and Quality Control, Faculty of Veterinary Medicine, Urmia University, Iran
3 Department of Pathobiology and Quality Control, Artemia and Aquatic Animals Research Institute, Urmia University, Iran
* Corresponding author: email@example.com
This study was carried out to evaluate the use of Lactobacillus casei and Saccharomyces cerevisiae as probiotic on growth and immune system in rainbow trout (Oncorhynchus mykiss). For this purpose, one thousand and fifty fish (25.6±2 g average weight) were obtained from a local fish farm in Urmia, Iran. Healthy fish were kept in 1000 L tanks for 10 days for acclimation to the laboratory conditions. Then, fish were randomly divided into 7 groups each with triplicate as follow: 1) as control that were fed with commercial diet, 2) fed with 107 CFU/g Lactobacillus casei, 3) fed with 10 CFU/g Saccharomyces cerevisiae, 4) fed with 107 CFU/g 2ME1 treated S. cerevisiae, 5) fed with 107 CFU/g L. casei and 107 CFU/g S. cerevisiae in combination, 6) fed with 107 CFU/g L. casei and 107 CFU/g 2ME treated S. cerevisiae in combination and 7) fed with Oxytetracyclin; 25 mg/KgBW. The probiotic were sprayed into the feed slowly, and allowed to dry at room temperature for 2 h. For control group only commercially feed was used without addition any probiotic. Fiftty fish were randomly placed in tanks and fed
for 45 days, and then the feed was changed to unsupplemented control diet for 15 more days. Sampling was scheduled at day of 0, 15, 30, 45 and 60 for biometery and humeral immune assay. Results showed that diet supplementation with probiotic (groups 2, 3, 4, 5 and 6) significantly (P<0.05) improved growth parameters in rainbow trout. Immunological analysis showed that lysozyme activity, alternative complement activity and total serum immuoglobulins level were significantly (P<0.05) increased than the control group.
Based on our results we conclude that additing both L. casei and Saccharomyces cerevisiae in combination to the diet could improve growth and health status of rainbow trout.
Key words: Rainbow Trout, Probiotic, Saccharomyces cerevisiae, Lactobacillus casei, growth parameters, immune response
Rainbow trout is a popular salmonid fish species and has received great attention in terms of importance to aquaculture and remain a core of inland fish production in many countries throughout the world (Merrifield et al. 2010). The intensive use of antibiotics to prevent and control bacterial diseases in aquaculture has led to an increase in antibiotic-resistant bacteria. Therefore, several alternative strategies to the use of antimicrobials have been proposed, such as the use of probiotics as biological control agents (Abdel-tawwab et al. 2008). Probiotics, live microbes that may serve as dietary supplements to improve fish growth and immune responses, have received some attention in aquaculture (Gatesoupe, 1999; Irianto and Austin, 2002; Kesarcodi-Watson et al., 2008). The application of probiotics is increasingly used in disease control against bacterial fish pathogens especially in Asia and South America (Sharifuzzaman and Austin 2009).
Thus, this study was carried out to evaluate the use of Lactobacillus casei and Saccharomyces cerevisiae as probiotic on the growth and immunity in the rainbow trout (Oncorhynchus mykiss).
Materials and Methods
One thousand and fifty fish (25.6±2 g average weight) were obtained from a local fish farm, Urmia, Iran. Healthy fish were kept in 1000 L tanks for 10 days for acclimation to the laboratory conditions. Then, fish were randomly divided into 7 groups each with triplicate as follow: 1) as control that were fed with commercial diet, 2) fed with 107 CFU/g Lactobacillus casei, 3) fed with 10 CFU/g Saccharomyces cerevisiae, 4) fed with 107 CFU/g 2ME treated Saccharomyces cerevisiae, 5) fed with
10 CFU/g Lactobacillus casei and 10 CFU/g Saccharomyces cerevisiae in combination, 6) fed with 107 CFU/g Lactobacillus casei and 107 CFU/g 2ME treated Saccharomyces cerevisiae in combination and 7) fed with Oxytetracyclin (25 mg/Kg of body weight). The probiotic were sprayed into the feed slowly, and allowed to dry at room temperature for 2 h. For control group only commercially feed was used without addition any probiotic. 2ME treatment of yeast cells was performed according to Tukmechi et al. (2011). Fifty fish were randomly placed in tanks and fed for 45 days, and then the feed was changed to unsupplemented control diet for 15 more days. Sampling was scheduled at day of 0, 15, 30, 45 and 60 for biometry and humeral immune assay. Each time nine fish randomly were sampled from each group (3 fish per replicate) and immediately anaesthetized with clove powder (200 mg/l).Total, standard and fork length, total weight, feed conversion ratio, Feed Efficiency, weight gain and special growth rate were calculated and recorded for each group, separately. Blood was collected by vein puncture and transferred into sterile tubes and allowed to clod at room temperature and serum was separated for Immunological assays. Lysozyme activity in serum was determined according to the method of Demers and Bayne (1997), alternative complement activity was assayed based on the hemolysis of rabbit red blood cells (RaRBC) as described by Waley and
North (1997) and total immunoglobulin level was assayed following the method of Siwicki et al. (1994). All the measurements were made in triplicate. The results were subjected to analysis of variance (ANOVA) followed by least significant differences (Tukey) test. Correlation coefficients were significant with P<0.05.
Results and discussion
Results showed that diet supplementation with probiotic (groups 2, 3, 4, 5 and 6) significantly (P<0.05) increased total weight and weight gain in rainbow trout. According to the measurements (Table 1) 6 group had the highest total weight (113±5 g) after 45-day trial and control group had the lowest (90.66+4 g). Although, SGR was significantly (P<0.05) higher in groups 6 and 5 that were fed with mixture of probiotics, but it also had significant differences to the control and 7 group in other probiotic treatments.
Table 1. Final weight (g) of rainbow trout fishes were fed by terial treatments for 60 day. Each value is (mean + SD) is and n=9.
The Day of Sampling
2ME Treated S. cerevisiae
L. casei + S. cerevisiae
L. casei + 2ME Treated S. cerevisiae
The same superscript alphabets in the same row are not significantly different at P < 0.05.
Immunological analysis showed that by using probiotic diets, lysozyme activity, alternative complement activity and total serum immunoglobulin level were constantly increased until 45th day, and after that, slowly decreased until 60th day. Lysozyme activity, was
significantly (P<0.05) higher in 4,5 and 6 group, alternative complement activity in 5 and 6 group and total serum immunoglobulin level in 2, 5 and 6 group.
These results agree with that obtained with catla carp, mrigal carp, hybrid striped bass, Nile tilapia, Israeli carp and Japanese flounder
(Abdel-Tawwab et al. 2008).
Despite the large number of probiotic studies which have assessed immunological and haematological parameters the immuno-modulatory effects of probiotics in fish systems are, at present, poorly understood (Merrifield et al. 2010) but the immune-stimulating properties of probiotics have been recognized as the key mode of action protecting fish against bacterial infections (Sharifuzzaman and Austin 2010). This particular role of probiotics corroborate well to the present study where several innate immune parameters were enhanced in fish treated with L. casei and S. cerevisiae than those of the control's. Based on our results we conclude that addition both L. casei and S. cerevisiae in combination to the diet could improve growth and health status of rainbow trout.
Abdel-tawwab, M., Abdel-rahman, A.M. and Ismael, N.E., 2008. Evaluation of commercial live bakers ' yeast, Saccharomyces cerevisiae as a growth and immunity promoter for Fry Nile tilapia, Oreochromis niloticus (L.) challenged in situ with Aeromonas hydrophila. Aquaculture 280, 185-189.
Demers NE, Bayne C.J., 1997. The immediate effects of stress on hormones and plasma lysozyme in rainbow trout. Developmental and Comparative Immunology; 1997; 21:363-73.
Gatesoupe, F.J., 1999. Review: The use of probiotics in aquaculture. Aquaculture 180: 147-165.
Irianto A., and Austin B., 2002. Use of probiotics to control furunculosis in rainbow trout, Oncorhynchus mykiss (Walbaum). Journal of Fish Diseases 25:333-42.
Kesarcodi-Watson, A., Kaspar, H., Josie Lategan, M., Gibson, L., 2008. Probiotics in aquaculture: the need, principles and mechanisms of action and screening processes. Aquaculture 274: 1-8.
Merrifield, D.L. et al., 2010. The current status and future focus of probiotic and prebiotic applications for salmonids. Aquaculture 302: 1-18.
Sharifuzzaman, S.M. and Austin, B., 2010. Development of protection in rainbow trout (Oncorhynchus mykiss, Walbaum) to Vibrio anguillarum following use of the probiotic Kocuria SM1. Fish and Shellfish Immunology 29(2): 212-216.
Sharifuzzaman, S.M. and Austin, B., 2009. Influence of probiotic feeding duration on disease resistance and immune parameters in rainbow trout. Fish and Shellfish Immunology 27(3): 440-445.
Siwicki AK, Anderson DP, Rumsey GL. 1994. Dietary intake of immunostimulants by rainbow trout affects non-specific immunity and protection against furunculosis. Veterinary Immunology and Immunopathology 41:125-39.
Tukmechi, A. et al., 2011. Dietary administration of beta-mercapto-ethanol treated Saccharomyces cerevisiae enhanced the growth, innate immune response and disease resistance of the rainbow trout, Oncorhynchus mykiss. Fish and Shellfish
Immunology, 30(3): 923-928.
Waley K. and North J., 1997. Hemolytic assays for whole complement activity and individual components. In: Dodds, A. W. and Sim, R. B. (Eds), Complement: A practical Approach, Vol. 1. Oxford University Press, Oxford, Great Britain, pp.19-47.
Evaluation of germ cells changes of female shrimp Litopenaous vannamei in Bandarga station
Malollahi, A.1*, Pazir, K.2, Ghorbani, R.3, Zendebodi, A.4, Nazari5
1 2, 3, 4, 5 Shrimp Research Center * f.malollahi @ yahoo.com
No doubt identifying the microscopic structural changes of oocytes is very important to recognize the time of egg maturation and egg fertilized. In this regard, during a 7-month period from August 1391 January 1390 Change of Vannamie shrimp oocytes were examined at Bandargah Station.After shrimp caught from reservation tank operations autopsy were performed on specimens. We removed and weighed the ovary to determine the GSI. Ovarian tissue of the samples was kept for 24 hours in Davidson's solution for section and staining.Ovarian histological sections of samples and method of H&E stain were performed. Results obtained show that GSI values also increased with increasing temperature. This condition had coordinated with the development of oocytes. Therefore, during the different month we showed different stages of ovarian maturation as follows. was observed Pre-vitellogenic ovary in February, March, Early vitellogenic stage in April May and let-vittelogenic in late spring to summer.
Key words: egg maturation, shrimp Vannamie, GSI, ovarian histology, Bandargah.
Vannamie shrimp (litopenaeus vannamie) is one the most important cultured species. During 2004, global production was 1,116,000 tones of this species. So any attempt to improve the quality and quantity of a particular species is very important. One of the factors that have important role in the proliferation and development of shrimp species is identified any stage of oocyte development and maturation. Four distinct stages of ovary wild tiger shrimp has been reported as follows: pre vitellogenic, vitellogenic, cortical rod and spent which was based on histological studies of ovary tissue (Josefa, 1989). This results as afterwards proposed by Bruno Ribeiro de Campos et. al. (2009), too. Considerable, color, shape, GSI (gonado somatic index) values and microscopic changes of gonads in a kind of crab were investigated by Hui-Chen Kao1, et al 1999. It is concluded that were four distinct stages of oocyte maturation in female crabs. In the other hand, gonadosomatic index and histological section were used for ovarian maturation of Metapenaeus monoceros were included five stages of oocyte growth such as: pre- vitellogenic, early vitellogenic, late vitellogeni and Spent (Abraham and Manisseri,
2012). Also, in further studies showed that were four distinct stages of ovarian from giant freshwater prawn, Macrobrachium rosenbergii (Meeratanas and Sobhon, 2007). In this study, an attempt has been made to determined oosyte maturation in shrimp L. vannamie in the Bandargah station of Iranian shrimp research center from Boushehr province, applying histological of ovary and gonado-somatic
Material and Methods
This study was conducted during Dec 2011 to Sep 2012. Female Shrimps of L. vannamie specimens were sampled from maintenance tank than they were carried to the histological laboratory of Iranian shrimp research center. So, individual shrimps were weight and ovary were
measured by AND measurement (0.001 g).
Female gonado-somatic index (GSI) was calculated by equation: ovary weight x 100
In this study were used of saline solution for cleaning the samples than they were cut and fixed in Davidson's solution. After 24 hours the specimens were transferred to the 70% alcohol for long-term storage. Tissues were dehydrated and cleared in ethanol and xylene respectively. Gonad tissues were embedded in paraffin and cut of tissues with 5-6 um thick by microtome. So, the tissues sections were stained by heamatoxylin and eosin according to Afsharnasab et. al., 2007.
The ovaries are paired organs in the postero -dorsal part of the shrimp body. Their branches are located at the rear of the muscle and hepato-pancreas. At the first time of ovarian cycle they look like tube shape and clearly And are difficult to distinguish from their surrounding tissues. Oocytes gradually increases with age, white, milky, yellow and dark green are observed. Figure 1 shows an overview of the current shrimp ovary.
Figure 1: Ovary of penaeus vannamie in bandargah station.
The results of gross signs showed that the mean ovarian and GSI were differenced in each month (table1)
Table1: The gross signs of ovarian stages of female shrimps in different month.
Mean shrimp weight
The mean weight of the ovaries
Based on histological findings were observed three different stages in reproductive organs of female shrimps. Oogenesis stage is initial stage of oogony but this stage wasn't observed in this study. In Pre-vittelogenic stages, the ovaries were Clear, tubular, short branches and were laid in posterior region of stomach. The most important characteristic of oocytes were existed clusters form. Also, the nucleolus of oocytes were near the nuclear membrane.
Figure 1: clusters form of oosyte (magnification:10X- 20X- 40X)
Figure 2: Nuclear membrane and nucleolus in the side of nucleus (magnification100x)
First vittelogenises Stage: In this phase ovarian colors seem slightly darker. Anterior branches are clearly observed. Cytoplasm of oosyte due to Yolk granules it looks grainy.
Figure 3: Cytoplasm and Yolk magnification (10x-20x-40x).
Figure 4: Cytoplasm and Yolk magnification 100x
Last vittelogenesis Phase: At this stage the oocyte cytoplasm is granules because Yolk granules and lipid granules within the cytoplasm of the oocyte has been developed.
Figure 5 ovary with yolk granules in the oocyte (10x-20x-40x)
Stage IV (mature): At this point Due to differences in reproductive behavior and physiological strategy of Litopenaous vannamei we could not see ripe oocyte.
Our result analyses of the ovaries revealed three developmental stages of Litopenaous vannamei Pre-vittelogenic/ First vittelogenises and Last vittelogenesis. Two stages of maturation could not see, Oogenesis and spent. These were phases I, II and III (corresponding to the maturing stage.
According to the results it could be argued that shrimps Can process their sexual in the tank.
In addition between GSI and oocyte maturation was direct ratio. In the other hand in this species growth of oocyte like another fishes depending on the ambient temperature.
Bruno Ribeiro de Campos; Luiz Felipe Cestari Dumont; Fernando D'Incao and Joaquim Olinto Branco(2009). Ovarian development and length at first maturity of the sea-bob-shrimpXiphopenaeus kroyeri (Heller) based on histological analysis.
Hui-Chen Kao1, Tin-Yam Chan1,* and Hsiang-Ping Yu2 (1999). Ovary Development of the Deep-water Shrimp Aristaeomorpha foliacea (Risso, 1826) (Crustacea: Decapoda: Aristeidae) from Taiwan.
JOICE ABRAHAM* AND MARY K. MANISSERI (2012). Histological and morphological changes associated with ovarian development of speckeled shrimp Metapenaeus monoceros (Fabricius, 1798).
Josefa D. Tan-Fermin, Rosario A. Pudadera(1989). Ovarian maturation stages of the wild giant tiger prawn, Penaeus monodon Fabricius . Volume 77, Issues 2- 3, March 1989, Pages 229-242
Meeratanas,P., Sobhon,P.,( 2007 ).Classification of differentiating oocytes during ovarian cycle in the giant freshwater prawn, Macrobrachium rosenbergii de
man.Aquaculture. V 370. PP 249- 258.
Sakaji, H. (2001), Maturation and spawning of the small penaeid shrimp Metapenaeopsis dalei in Tosa Bay, Pacific coast of southern Japan.
Fisheries Science, 67: 444-448. doi: 10.1046/j.1444-2906.2001.00280.x
Z Ayub, M Ahmed (2002). A description of the ovarian development stages of penaeid shrimps from the coast of Pakistan
The Effect of Artemia urmiana Enriched with Linseed
Oil on Resistance to Temperature Stress and Oxygen Deficiency in Cichlasoma severum Larvae
Javad Motamedi Tehrani,1*, Esa Ebrahimi Dorche2, Sayed. Amir. Hosein Goli3, Paria Akbary4, Ali Nezameslami5
1 MSc student in Fishery, Isfahan University of Technology, , Isfahan, 84156-83111, Iran
2 Department of Fisheries, Faculty of Natural Resources, Isfahan University of Technology, Isfahan, 84156-83111, Iran
3 Department of Food Science, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111, Iran
4 Ph.D. student in Fishery, University of Tehran.,
5 MSc graduate, Fishery Dept., Isfahan University of Technology , Isfahan, 8415683111, Iran
Corresponding author's email: j motamedi firstname.lastname@example.org Introduction
In this study, newly hatched artemia and enriched artemia with linseed oil were used as starter food for Cichlasoma severum larvae untile18 day; In the second phase of experiment (untile 36 days), Larvae of both treatments were fed with commercial diet. This research studied the effect of artemia napulii enriched with linseed oil on resistance to temperature stress and anoxia in severum fish larvae (Cichlasoma severum), Also,the effects of feeding with artemia nauplii of the two treatments on fatty acids profile of larval carcass were studied in addition to study of possible increase in non-saturated.
Materials and Methods
Artemia cysts used in this plan were supplied from Sepanta Mahiana Ariapars (58% hatched), decapsulated based on standard methods, and hatched according to the method of Lavens and Sorgeloos (1996). Artemia enrichment was performed based on Method of Clawson and Lovell (1992). Enrichment diets was added at times 18:00 and 00:00. The
two treatments (in a completely randomized design with 3 replicates per treatment) were: (1) larvae fed newly hatched nauplii, (2) larvae fed enriched artemia nauplii with linseed oil. The fish larvae in all treatments were fed 4 times per day (8, 12, 16, 20 hours). Artemia oil extraction (200 thousand Artemia nauplii for each repetition)was done according to method of Bligh and Dyer (1959) Was. Method fatty acid methyl esters were prepared according to Goli et al. (2008). Temperature Stress and Oxygen Deficiency was done according to method of Ako et al., 1992. the data was reviewed by Kolmogorov-Smirnov (K-S) and Levene tests to make sure of normality and homogeneity of variances respectively. Comparison of data average was carried out by Independent T test at confidence level 5% (P = 0.05). Data analysis was performed using SPSS application (Version 15).
At the end of the 36-day period,the larvae were exposed to high & low temperature stresses of 34-16°C respectively, for 96 hours during when no loss (0%) was seen between Treatment 1 (larvae fed with non-enriched artemia up to 18 days) and Treatment 2 (larvae fed with enriched artemia or linseed oil up to the early 18 days). Results of imposing anoxia stress for 2 minutes indicated no losses (0%) in the treatments after 24 hours, but imposing anoxia for 5 minutes indicated that after 24 hours there was no meaningful difference (p>0.05) between treatment 1 (52.5+1.42%) and treatment 2 (47.5+7.21%).
As in this study the aim of enriching artemia with linseed oil is to feed larvae of Cichlasoma severum (an ornamental freshwater fish), the content of linolenic & linoleic acids after enrichment is more focused because Van Stappen showed, in 1996, that fatty acids requirement of freshwater fishes differs from that of seawater fishes. Also, he added that freshwater species need linolenic & linoleic fatty acids and seawater species need EPA and DHA.The results of this study prove that feeding
severum larvae on artemia enriched with linseed oil did not lead to a meaningful increase of their resistance to stressful conditions resulted from temperature changes and lack of oxygen for 5 minutes (Table 8). However, loss percent of larvae fed with enriched artemia was lower than that of the control group because of high linolenic acid content in treatment 2, supporting the results of studies by Smith et al. (2004), Van Stappen (1996) and Kiron et al. (1995).
Fatty acids Profile of larvae fishes carcass fed with non-enriched artemia nauplii and
enriched with linseed oil( %)_
Carcass of larvae fed with Carcass of larvae fed with Fatty acids non-enriched artemia artemia nauplii enriched with _nauplii_linseed oil_