Efeitos de dietas suplementadas com vitamina e sobre o crescimento, eficiência alimentar e parâmetros hematológicos e fisiológicos do tambaqui Colossoma macropomum (CUVIER, 1818)

Abstract

The vitamin E inclusion in fish food is related to improvements in in growth performance and nonspecific immune response for different species. The present study aimed to evaluate the effect of different vitamin E levels (DL acetate-α-tocopherol, 50% active) on productive performance, hematological variables, hematometric index and physiological parameters of tambaqui (Colossoma macropomum) fingerlings. A total of 150 fishes with an average weight of 2.94 ± 0.14 g and initial average standard length of 4.29 ± 0.07 cm were distributed in aquariums (300 L) in water recirculation system, temperature of 27.13 ± 0.45 ºC, pH 7.16 ± 0.45, dissolved oxygen 7.15 ± 0.88 mg L-1, electronical conductivity 0.142 ± 0.05 (μs cm-1); ammonia 0.00 ± 0.00 (ppm) and nitrite 0.19 ± 0.25 mg L-1. The stocking density was 10 fishes per experimental unity. The inclusion levels of α-tocopherol in the diet were 0, 250, 700 and 1,000 mg kg-1. Thus, was used a completely randomized design with five treatments and three repetitions, where the fishes were fed three times a day during 90 days. The results indicate that the different vitamin E levels did not affect the productive performance of tambaqui fingerlings. However, the inclusion of 1,000 mg kg-1 of α-tocopherol reduced (P<0.05) the glucose amount in comparison to the supplemented treatments with 0 and with 250 mg kg-1. The hematocrit, total protein, erythrocytes number and hematometric index of tambaqui fingerlings were not affected (P>0.05) by α-tocopherol supplementation. In differential leukocyte count, there was no significant difference of lymphocyte number, monocytes and basophiles. However, the neutrophil number was greater in the control treatment (P>0.05), while eosinophil and specials granulocytic cells were better than control treatment (P<0.05), while the eosinophils number was special granulocytic cells was higher than treatments with 700 mg kg-1 and 250 mg kg-1 of α-tocopherol, respectively. Although vitamin E supplementation in the diet did not influence the productive performance of tambaqui fingerlings, the fishes fed diet nonsupplemented showed increased of neutrophils number, demonstrating greater susceptibility of these fishes to inflammation process.