Orientador: Flávio Ruas de Moraes / Banca: Claudinei da Cruz / Banca: Eduarado Makoto Onaka / Resumo: O cromo trivalente é um micronutriente essencial para saúde dos animais atuando no metabolismo de carboidratos, gorduras e proteínas. Porém produz efeitos antagônicos como redução do cortisol plasmático e potencialização da insulina. A suplementação na dieta de peixes visa à redução de problemas decorrentes do estresse devido à melhora do sistema imune. Assim o presente trabalho avaliou o cromo trivalente como agente imunomodulador, utilizando 0, 12, 18, 36 mg de cromo/kg de dieta durante 90 dias, estudando o desempenho produtivo, a hematologia e a resposta celular na inflamação aguda induzida por infiltrado de Aeromonas hydrophila e tioglicolato na bexiga natatória de pacus (Piaractus mesopotamicus). Para o ensaio de desempenho e hematologia os peixes foram distribuídos em esquema fatorial 4X2, sendo quatro tratamentos e duas repetições. Os dados revelaram que não houve interferência do cromo na conversão alimentar, no ganho de peso, no ganho de comprimento total, no ganho de comprimento parcial e na taxa de crescimento específico. O número de eritrócitos, hematócrito e o volume corpuscular médio embora apresentassem diferenças significativas (P<0,05) após 90 dias de suplementação em relação aos peixes não suplementados, mostraram amplas e inconclusivas oscilações. Portanto a suplementação com cromo trivalente não interferiu nestes parâmetros...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The trivalent chromium is an essential element animal's health acting over carbohydrates, fat and proteins metabolism. However, this substance produces antagonist effects such as reduction of plasma cortisol and increase of insulin. The purpose of the supplemented given to fishes was to decrease disturbance caused by stressing factors due to immunity improvement. Therefore, the present work aimed to evaluate the trivalent chromium as an immunomodulator substance by using 0, 12, 18, and 36 mg/kg of chromium offered during 90 days, to study the growth, blood parameters and cellular response in acute inflammation induced by Aeromonas hydrophila and thioglycolate in the swim bladder of Pacu (Piaractus mesopotamicus). Fishes were allocated into four groups, at a 4X2 factorial and two replicates. Data revealed there was no influence of chromium on feed conversion, weight gain, total length gain, partial length gain and specific growth rate. Although some differences (P<0.05) were found for erythrocytes number, hematocrit and mean corpuscular volume (MCV) values after 90 days of experiment in comparison to non supplemented fishes, all differences found were wide and showed no conclusive oscillations. The fishes were euthanatized by deepening of anesthesia and exudates was collected. The results showed a progressive accumulation of total inflammatory cells after 6, 24 and 48 h for both stimulated groups. Control group was injected saline solution. The results showed a progressive accumulation of total inflammatory cells after 6, 24 and 48 h for both stimulated groups. Fishes fed diet consisting of 18 mg/kg of trivalent chromium presented an accentuated inflammatory reaction, with accumulation of thrombocytes, lymphocytes and of a lesser amount of macrophages in A. hydrophila induced fishes. Lymphocytes and thrombocytes were predominant in thioglycolate induced fishes...(Complete abstract, click electronic access below) / Mestre