Department of Fisheries, Ahwaz Branch, Islamic Azad University, Ahwaz, Iran
This study aimed to examine the effect of fatty acid in the diet on changes the incidence of the Red-head Syndrome under temperature stress and hypoxia in white leg shrimp (Litopenaeus vannamei) during 8 weeks. For this purpose, shrimps were fed by 4 diets (diet 1: containing 7.02% of total fat; diet 2: containing 6.41% of total fat; diet 3: containing 8.05% of total fat; diet 4: containing 6.41% of total fat with 1750 mg/kg of vitamin E), under 3 stressors (S1: no challenge to environmental stresses; S2: with hypoxic stress (2.0±1.0 ppm); S3: with increasing temperature stress (36±2°C). The results of the hypoxic stress on the incidence of redness in L. vannamei fed with different levels of fatty acids showed that there were differences significantly (p<0.05). Temperature increase although showed no differences between healthy shrimps(p>0.05) but, there were significant difference among red-headed shrimp in treatment 1, 2 and 3 (p<0.05). The examination in treatments 2 and 3 showed hepatopancreatic were loss the columnar structure so thatelongated cells and dilated tubules were observed. Some B cells had no vacuoles and were not fully developed. The number of R cells was low and basophilic F cells were convex. In treatment 4, the cells have few reserves and were normal. Some B cells were degenerated. The height of the tubules was lower than normal, but no inflammatory reaction was observed in the tissue. In treatment 4, cell showed better conditions than treatments 2 and 3. Accordingly, B cells were present well and R cells showed moderate storage. In general, it can be concluded that the use of vitamin E can reduce the complication of redness and minimal cell damage to hepatopancreatic tissue in L. vannamei.