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The physiological responses of juvenile tambaqui (Colossoma macropomum) fed commercial feed supplemented with different concentrations of camu camu (Myrciaria dubia) were evaluated. The design was completely randomized, with treatments arranged in a factorial design with three proportions of camu camu (15%, 30% and 45%) and a control treatment (100% commercial diet), with four replicates per treatment. A total of 96 tambaqui specimens were used, with a mean initial weight of 11.69 ± 2.68 g and a mean length of 7.06 ± 0.44 cm. After 30 days, hematological parameters, metabolic variables, growth and fish swimming performance were evaluated. The different proportions of camu camu in the diet did not cause significant changes to the tambaqui's hematological parameters during the feeding period, except for hemoglobin (Hb) concentration and mean corpuscular hemoglobin concentration (MCHC) after the 30th day, and hematocrit (Ht) after the swimming stress test, which increased significantly (p < 0.05). The significant increases in metabolic variables, such as cortisol, glucose, proteins and triglycerides, and in hematologic variables after the Ucrit test reflect, respectively, biochemical adaptations for maintenance of the energy mobilization process and a regulatory necessity in tissue oxygen demand during intense exercise. Fish fed 15% and 30% camu camu gained the most weight and achieved the best swimming performance, respectively. The results for camu camu concentrations above 30% suggest a saturation of its intrinsic properties in the diet at this level and a loss of nutrients from the commercial feed replaced by the fruit, reducing productive performance and nutritional assimilation.Keywords: Amazon, Colossoma macropomum, Myrciaria dubia, hematology, ascorbic acid. Alterações em parâmetros fisiológicos de tambaqui (Colossoma macropomum) alimentados com dietas suplementadas com fruta amazônica camu camu (Myrciaria dubia) ResumoAs respostas fisiológicas de juvenis de tambaqui (Colossoma macropomum) alimentados com ração comercial suplementada com diferentes concentrações de camu camu (Myrciaria dubia) foram avaliados. As amostras analisadas foram inteiramente casualizadas, com os tratamentos arranjados em esquema fatorial com três proporções de camu camu (15%, 30% e 45%) e um tratamento controle (ração comercial 100%), com quatro repetições por tratamento. Um total de 96 amostras de tambaqui foram utilizadas, com um peso médio inicial de 11,69 ± 2,68 g e um comprimento médio de 7,06 ± 0,44 cm. Após 30 dias, foram avaliados os parâmetros hematológicos, variáveis metabólicas, crescimento e desempenho natatório de peixes. As diferentes proporções de camu camu na dieta não causou alterações significativas nos parâmetros hematológicos dos tambaquis durante o período de alimentação, com exceção de hemoglobina (Hb) e concentração de hemoglobina corpuscular média (CHCM), após o 30º dia, e hematócrito (Ht), após o teste de nataçãoBraz.

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Growth and hematological responses of tambaqui fed different amounts of cassava (Manihot esculenta) ABSTRACTTambaqui,Colossoma macropomum is a fish of primary importance in Brazilian aquaculture and in the Amazon region in particular. The aim of this work is to analyze the combined effects of physical training and levels of dietary cassava (Manihot esculenta) on the hematological parameters, food intake, conversion efficiency, growth ratio and swimming performance of this fish. A diet for tambaqui consisting of 30% cassava caused decreases in weight gain and specific growth rate compared with the control group. Diets containing 15% or 45% cassava did not affect these indices and did not cause hematological changes in tambaqui juveniles, indicating that some amount of cassava can be used as an alternative energy source for this important aquaculture species.Keywords: teleosts, growth, feed evaluation, stress, blood RESUMO

We used respirometric theory and a new respirometry apparatus to assess, for the first time, the sequential oxidation of the major metabolic fuels during the post-prandial period (10 h) in adult zebrafish fed with commercial pellets (51% protein, 2.12% ration). Compared with a fasted group, fed fish presented peak increases of oxygen consumption (78%), and carbon dioxide (80%) and nitrogen excretion rates (338%) at 7-8 h, and rates remained elevated at 10 h. The respiratory quotient increased slightly (0.89 to 0.97) whereas the nitrogen quotient increased greatly (0.072 to 0.140), representing peak amino acid/protein usage (52%) at this time. After 48-h fasting, endogenous carbohydrate and lipid were the major fuels, but in the first few hours after feeding, carbohydrate oxidation increased greatly, fueling the first part of the post-prandial specific dynamic action, whereas increased protein/amino acid usage predominated from 6 h onwards. Excess dietary protein/amino acids were preferentially metabolized for energy production.