ABSTRACT Promising species for aquaculture need to have their nutritional requirements defined. Considering that protein is the most expensive macronutrient in aquaculture diets, the present study aimed to estimate the protein requirement of curimatãpacu fed with diets containing two lipid levels. Thus, eight experimental diets were formulated to contain 20, 25, 30 and 35% of crude protein (CP) associated to 11 and 15% of crude lipids (CL) were formulated, constituting a completely randomized factorial design (4 CP x 2 CL) with three replicates per treatment. The juveniles (3.6 ± 0.01 g) were fed daily with 6% of the biomass, three times a day (08:00, 12:00 and 16:00 h) for 70 days. The protein requirement was estimated by the combination of the broken line and quadratic regression models. The CP concentration in the diets was the only factor influencing (P < 0.05) the growth and feeding efficiency variables of the fish, without interaction (P > 0.05) with the CL level of the diets. The requirement for weight gain and fish feed efficiency was estimated at 32.5 and 34.5% CP. Protein retention decreased (P < 0.05) in proportion to CP elevation. Fish fed 15% CL had higher (P < 0.05) body lipid deposition. On the other hand, the increase of CP of the diets decreased (P < 0.05) lipid deposition in juveniles. Therefore, it is recommended that young curimatãpacu between 3 and 27 g in weight should be fed diets containing 32.5-34.5% CP and 11% of CL, equivalent to a protein: energy ratio of 22-23 mg kJ−1

ABSTRACT The apparent digestibility coefficients (ADC’s) of dry matter (DM), crude protein (CP), and gross energy (GE) of conventional feedstuffs (cottonseed meal-CSM, soybean meal-SBM, wheat bran-WHB, corn-COR) and regional alternative feedstuffs (common bean residue meal-CBR, mesquite meal-MES, pasta by-product meal-PBM) were determined for hybrid juvenile tambacu Colossoma macropomum × Piaractus mesopotamicus. The apparent DM and GE digestibility of feedstuffs decreased (p<0.05) as fiber content of the ingredients increased. No differences (p>0.05) were found among ADC’s of PBM and COR. The lowest CP ADC among energy sources was observed in MES; the lowest CP ADC among plant protein sources was observed in CBR. Information about the ADC’s of conventional and alternative feedstuffs for tambacu is essential to formulate low-cost diets and can contribute to regional development.

A intensificação dos sistemas de produção em aquicultura expõe os peixes a inúmeros estressores, os quais afetam negativamente seu crescimento e limitam a rentabilidade dos sistemas de aquicultura. Este estudo determinou o efeito de níveis crescentes de mananoligossacarídeos dietéticos sobre o crescimento e morfologia intestinal do pacu. Os peixes (44,04 g) foram aleatoriamente distribuídos em 32 tanques (500 L; 10 peixes por tanque) e alimentados por 63 dias com uma dieta comercial suplementada com 0,0; 0,2; 0,4; 0,6; 0,8; 1,0; 1,5 e 2,0% de mananoligossacarídeo dietético. Os parâmetros de crescimento não diferiram (P>0,05) entre os peixes alimentados com a dieta controle e as dietas suplementadas com mananoligossacarídeo. O perímetro das vilosidades intestinais foi realizado nos peixes alimentados com a dieta controle, 0,4 e 1,5% de mananoligossacarídeos dietéticos e também não apresentaram diferenças (P>0,05) entre os tratamentos. A suplementação dietética de mananoligassarídeos não teve efeito no pacu. Estudos relacionados à caracterização da microbiota intestinal e experimento que reproduz sistemas comerciais de produção de peixes são necessários para determinar o uso efetivo deste suplemento dietético para a espécie.

Intensification of aquaculture production systems exposes fish to numerous stressors, which may negatively affect their growth and limit profitability of aquaculture systems. This study determined effects of increasing levels of dietary mannanoligosaccharides on growth and intestine morphology of pacu. Fish (44.04 g) were randomly distributed into 32 tanks (500 L; 10 fishes per tank) and fed during 63 days with a commercial diet supplemented with 0.0; 0.2; 0.4; 0.6; 0.8; 1.0; 1.5 and 2.0% dietary mannanoligosaccharides. Growth parameters did not differ (P>0.05) between fish fed control diet and mannanoligosaccharide supplemented diets. Intestinal villi perimeter was performed in fish fed control diet, 0.4 and 1.5% dietary mannanoligosaccharides and also showed no differences (P>0.05) between treatments. Dietary supplementation of mannanoligosaccharides unclear did not have effects on pacu. Studies on the characterization of intestinal microbiota together with experiment that reproduce commercial fish production systems rearing conditions are necessary to determine the effective use of this dietary supplement for the species.

Sistemas intensivos de produção utilizam 100% de dietas artificiais sendo que, qualquer imbalanço ou deficiência de algum nutriente pode ocasionar surtos de doenças e perdas econômicas. O presente estudo determinou o efeito de níveis crescentes de vitamina E na dieta sobre o desempenho e hematologia de juvenis de pacu. Os peixes foram alimentados por 90 dias até aparente saciedade com dietas semi purificadas contendo 0,0; 25; 50; 150; 300 ou 600 mg.kg−1 de DL-α-tocoferil-acetato, rações em um delineamento experimental inteiramente casualizado (n=4). Parâmetros de desempenho e hematológicos foram coletados e analisados. Peixes alimentados com ração de 150 mg.kg−1 de vit E apresentaram maior ganho de peso (p<0,05) e taxa de crescimento específico. Hematócrito, número de eritroblastos e proteina total plasmática foram maiores (p<0,05) nos peixes alimentados com a dieta insenta de vitamina E. O suplemento de vitamina E em dietas artificiais é essencial para o crescimento e a manutenção da eritropoiese nos valores normais para a espécie.

Intensive fish production systems are characterized by 100% artificial feeding, so any dietary imbalances or deficiencies may lead to diseases outbreaks and economic losses. This study was set out to determine the effects of increasing levels of dietary vitamin E on growth and hematology of juvenile pacu. Fishes were fed for 90 days, twice a day until apparent satiation with semi-purified diets containing 0.0; 25; 50; 150; 300 or 600 mg.kg−1 diet DL-α-tocopheryl acetate in a completely randomized design trial (n=4); biometrical and hematological data were collected and analyzed. Fishes fed with vit E diet (150 mg.kg−1) showed higher (p<0.05) weight gain and specific growth. Hematocrit, erythroblast number and total plasma protein were increased (p<0.05) in fishes fed diet with no vit E diet. Vitamin E supplementation in artificial diets for pacu is essential for growth and maintenance of normal erythropoiesis.