Effect of alfa-tocophenol and n-3 HUFA deficient diets on blood cells, selected inmune parameters and body composition of gilthead seabream (Sparus aurata)

Abstract

Fi sh ted a-tocopheroi depieted ciiets are reponed to S ~ O Wa m aricediy reáucd immunocompetence. Besides, essential fatty acids (EFA) deficient diets also cause disturbances in the physiology and biology of farmed fish. A feeding experirnent was conducted to study some effects causeú in gilthead sea bream (Sparus aurata) juveniles by EFA deficient diets and non supplemented g = i ~ c q k&~m~. ~ ! Juveniles of 55g were fed on diets containing three different supplementation levels of a-tocopherol (0, 50 and 150 mg a-tocopheroKg diet) plus an extra treatrnent consisting on 150 mg a-tocopherolkg diet and deficient on n-3 HITFA, EFA for marine fish. Biochemical composition of liver and muscle were studied, and some hematological parameters (Hematocrit, hemoglobin, red blood cell count, white blood cell count, MCHC, MCV and MCH) as well as NBT index and alternative serum complement pathway (ACHSO) were measured. In addition, histological modifications were also studied.Red blood cell fragility of the fish fed non-suplemented a-tocopherol diet was significantly higher than the others. Some significant differences were found between diets in some blood cells parameters. Histological differences such as dilated glomerular capillares and reduced space of Bowman' capsule were found in the kidney of fish fed on 11-3 HUFA deficient diets. Pancreatic darnages were also found in fish fed [he a-tocopherol deficicent diets. On the other Iiand, fish fed the deficient diets showed a lower NBT index and depleted ACH50 when compared with fish fed control diet. These results suggest that gilthead seabream fed diets with marginal deficiences in nutrients such as a-tocopherol and n-3 HUFA, essentid cornponents of the cell rnenibrane, Inay be exposed to a reduktion in their stress resistance potential. Further experiments are conducted to cIarify ihis fact.