RESUMO Objetivou-se avaliar diferentes granulometrias do milho (GM) em rações para juvenis de tambaqui sobre o desempenho zootécnico, composição da carcaça e viabilidade econômica. Foram distribuídos 160 peixes (3,86±0,03 g) em 20 aquários (40 L), em delineamento inteiramente casualizado com cinco tratamentos e quatro repetições. Os tratamentos consistiram de rações com diferentes GM: 150, 300, 500, 710 e 850 µm. Como parâmetros de desempenho zootécnico foram avaliados: consumo de ração (CR), ganho de peso (GP), conversão alimentar (CA), comprimento total final (CTF), comprimento padrão final (CPF), altura final (ALT), taxa de crescimento específico (TCE), taxa de desenvolvimento específico (TDE) e sobrevivência (SOB). Para composição de carcaça foram avaliados umidade, proteína bruta, extrato etéreo e matéria mineral. Na análise econômica das rações, foram analisados o custo médio com ração por quilograma de peso vivo ganho (CMR), o custo total de produção (CTP) e o índice de eficiência econômica (IEE). Os dados obtidos foram submetidos à análise de variância em nível de 5% de probabilidade e regressão polinomial. Verificou-se comportamento quadrático para as variáveis CR, GP, CA, TCE, TDE, CTF, CPF e ALT, obtendo-se os melhores resultados, respectivamente, para GM estimadas em 530,22; 555,40; 597,47; 566,75; 562,07; 557,48; 562,70 e 555,68 µm. Não houve influência das GM sobre a composição da carcaça. Verificou-se comportamento quadrático para as variáveis CTP e CMR, com valores mais altos para GM estimadas em, respectivamente, 600,44 e 602,11 µm. Conclui-se que granulometria do milho de 500 µm é indicada zootecnicamente e economicamente para rações de juvenis de tambaqui.

SUMMARY This study aimed to evaluate the performance, carcass composition and viability of different corn granulometry (CG) in diets for tambaqui. It was distributed 160 fish (3.86±0.03g) into 20 aquaria (40-L) in a completely randomized design with five treatments and four replications. The treatments consisted of diets with different CG: 150, 300, 500, 710 and 850 µm. As performance parameters were evaluated: feed intake (FI), weight gain (WG), feed conversion rate (FCR), final total length (FTL), final standard length (FSL), height (H), specific growth rate (SGR), specific development rate (SDR) and survival (SUR). For carcass composition were evaluated moisture, crude protein, ether extract and mineral matter. For the economic analysis of diet were analyzed the total cost of production (TCP), cost of feed per kg weight gain (CFK) and the index of economic efficiency (IEE). Data were subjected to analysis of variance at 5% probability and polynomial regression. There was quadratic effect for the variables FI, WG, FCR, FTL, FSL, H, SGR and SDR, obtaining the best results, respectively, for CG estimated at 530.22; 555.40; 597.47; 566.75; 562.07; 557.48; 562.70 e 555.68 µm. There was no influence of CG on the carcass composition. There was quadratic effect for TCP and CFK variables, with higher values for CG estimated at, respectively, 600.44 and 602.11 µm. It is concluded that CG of 500 µm is indicated to tambaqui feed.

The experiment was performed with 160 tambaqui (Colossoma macropomum) with average weight 11.01±2.08 g and total length 7.8±0.18 cm. Fishes were kept in sixteen aquariums with 56 L of water at 29.1±0.4 ºC of temperature, initial stocking density 1.97 g/L and constant aeration. The objective of this study was to assess the influence of photoperiod on fish performance. Treatments consisted of four photoperiods: T1 = 6 hours; T2 = 12 hours; T3 = 18 hours and T4 = 24 hours, with four replicates each. Fishes were fed twice a day with commercial extruded feed (28% of crude protein). The experiment was developed in closed circulation system, with volume of water renewal for each experimental unit equivalent to 40 times daily. Fish biometry was performed at the beginning of the experiment and at every 16 days, in order to follow the effects of treatments on juvenile development. Final weight, total length, standard length, height, feed intake, weight gain, feed conversion, survival, specific growth rate, protein efficiency rate and protein retention efficiency were assessed. Statistical analysis of variables was performed with application of the software SAEG version 9.1, for analysis of variance, regression analysis and Pearson correlation. Positive influence of photoperiod was observed for the studied variables in this study. The studied variables enhanced as the photoperiod increased, mainly between 15 and 22 hours. The photoperiod has significant influence upon growth traits of tambaqui (Colossoma macropomum).

O experimento foi conduzido para determinar digestibilidade aparente (CDA) da matéria seca (MS), energia bruta (EB) e proteína bruta (PB) da farinha de peixe (FP), farinha de carne e ossos (FCO), farelo de soja (FS), farelo de milho (FM) e farelo de trigo (FT) pelo Trichogaster leeri. Foram utilizados 20 peixes por aquário. Os aquários eram cilíndricos, fundo cônico, com 100 litros cada. A determinação dos CD foi feita por intermédio da metodologia de coleta total de fezes. As médias de temperatura, oxigênio dissolvido e pH durante o período experimental foram de 25,0 ± 1,13 oC; 3,91 ± 0,91mg/L e 5,22 ± 0,87, respectivamente. Os CD da MS, PB e EB foram respectivamente de 68,63, 89,25 e 87,30 para FP; 54,90, 65,95 e 80,62 para FCO; 60,13, 82,19 e 85,46 para FS; 39,30, 89,87 e 89,74 para FM; 22,5,17,45 e 19,54 para FT.

The experiment was conducted to determine the apparent digestibility (CAD) the dry matter (DM), gross energy (GE) and crude protein (CP) for fish meal (FM), meat and bone meal (MBM), soybean meal (SM), corn meal (CM) and wheat bran (WB) for Trichogaster leeri. It used 20 fish/tank of cylindrical shape with conical bottom, of 100 liters. CDA analysis was done through the method of total collection of feces. Average water temperature, dissolved oxygen and pH were 25,0 ± 1,13 oC; 3,91 ± 0,91mg/L e 5,22 ± 0,87, respectively. CAD of CP, GE and DM were 68,63, 89,25 and 87,30 for FM; 54,90, 65,95 and 80,62 for MBM; 60,13, 82,19 and 85,46 for SM; 39,30, 89,87 and 89,74 for CM; 22,5,17,45 and 19,54 for WB, respectively.