Abestract
Shrimp farming as one of the important aquaculture activities in the world and Iran is being developed and expanded and Vanamei shrimp has the best breeding characteristics. The presence of fat sources of unsaturated fatty acids in diets can be effective in reducing stress due to osmotic changes and improve growth rate and survival rate compared to other fat sources in the diet. Growth, survival, incidence of red head and hepatopancreatic tissue of western white shrimp under environmental stress and the effect of vitamin E on the improvement of the complication were studied. Therefore, in the present study, the effect of dietary fatty acid composition on growth, survival, incidence of red head and hepatopancreatic tissue of western white shrimp under environmental stress and the effect of vitamin E on the improvement of the complication were investigated. In this experiment, food rations were designed in the form of a control treatment and 3 experimental treatments and 3 replications for each treatment. The highest growth rate was obtained in treatment 1 and the lowest in treatment 2 (P <0.05). Examination of the results of physical and chemical parameters of water on different days showed that no significant difference was observed in different treatments (P> 0.05). The results of the effect of hypoxic environmental stress on the incidence of red-headed in western white shrimp fed with different levels of fatty acids during 8 weeks showed that there was a significant difference between treatments 1 and treatments 2, 3 and 4 (P <0.05). However, there was no statistically significant difference between treatments 2 and 3 (P> 0.05). Treatments 2 and 4 also showed significant differences (P <0.05). The results of temperature increase showed that healthy shrimps in treatments 1 and 4 were not significantly different from each other (P <0.05). Treatment shrimps showed a significant difference with treatments 2 and 3 (P <0.05). There was no statistically significant difference in shrimps with red head complication in treatments 1 and 4 (P <0.05). Also, shrimps with red head complication in treatments 2 and 3 were not significantly different. But there is a statistically significant difference between red-headed shrimp in treatment 1 and treatments 2 and 3 (P <0.05). According to the results, treatment 2, which has the lowest total fat content of 6.41%, shows the highest prevalence of red-headed. The results also show that the use of vitamin E antioxidant in treatment 4 significantly reduced the complication rate.
The results showed that there was a statistically significant difference in the amount of aspartate aminotransferase (AST) enzyme in different diets before stress and after environmental stress, decrease in oxygen and increase in temperature (P <0.05). In food-fed shrimp, the amount of enzyme at the time of stress increase temperature shows the highest increase in enzyme titer, which is more than 3 times the amount of enzyme before stress in the same shrimp. Is. According to the results, the amount of alanine aminotransferase (ALT) in food-fed shrimps fed 2 and 3 has increased sharply and the results of measuring this enzyme in different treatments with each other are statistically significant (P <0.05). In the study of hemolymph enzyme (ALT / AST test), the effect of environmental stresses was found and the ALT enzyme titer in red-headed shrimp was increased almost 3 times compared to healthy shrimp. In treatment 4 of the experiment, which is enriched with vitamin E supplementation, it was found that the prevalence of the complication did not increase in environmental stress conditions and did not show a significant difference in treatment with treatment 1 of the control diet (P <0.05). Therefore, it can be concluded that the use of vitamin E supplement antioxidants in the shrimp diet, especially in the shrimp diet, which is used by breeders at the end of the rearing period, can greatly reduce the stress of shrimp harvest time and greatly reduce the risk of red-headed.
Keywords: Redhead Complication, Vitamin E, Temperature increase, Decreased oxygen, Western White Shrimp, Environmental Stress,