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Vegetable crop residues, such as sugarcane bagasse (SCB), despite their limited biodegradability, are potential materials for anaerobic processes because of their low cost, high availability, and sugar content. The difficulty of biodegrading this type of material is primarily related to its chemical composition and to the complex interactions between its compounds (cellulose, hemicelluloses, and lignin). Thus, the following supercritical and near critical carbon dioxide (CO 2) pre-treatments were evaluated with and without the addition of sodium hydroxide (NaOH): (i) 40°C/70 kgf•cm-2 ; (ii) 60°C/200 kgf•cm-2 ; and (iii) 80°C/200 kgf•cm-2 , aiming to enhance the anaerobic biodegradability of SCB. The methanogenic production of SCB increased in all cases in which the material was pretreated, except the case in which NaOH was used together with a high temperature. The condition using CO 2 at 60°C/200 kgf•cm-2 was highlighted with a lignin removal of 8.07% and an accumulated methane production of 0.6498 ± 0.014 L N (273.15K, 1.01325 × 10 5 Pa), 23.4% higher than the value obtained with the untreated material. This condition also showed the highest net energy at the energy balance that was calculated for comparison with the tested conditions. The results showed that pre-treatments with near critical and supercritical fluids have the potential to reduce structural obstacles of lignocellulosic materials and to enhance their anaerobic biodegradability.

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Resumo -Este trabalho teve por objetivo avaliar o efeito de três rações experimentais com diferentes níveis protéicos (33,6%, 26,6% e 22,5%), comparadas a uma ração comercial (46,5%), no desempenho e crescimento heterogêneo de girinos de rã-touro (Rana catesbeiana). Os girinos foram mantidos, durante três meses, em caixas de amianto abastecidas com 1.000 L de água corrente, na densidade de 1 girino L -1. Os girinos foram alimentados, diariamente, com duas porções iguais ad libitum e foram submetidos, quinzenalmente, à pesagem. Os grupos alimentados com a ração com 46,5% de proteína bruta mostraram maior ganho médio de peso, porém apresentaram crescimento heterogêneo mais elevado, e alguns indivíduos apresentaram deformações nos membros (27% no início da metamorfose e 5% no final). Os girinos que utilizaram as rações com 33,6% e 26,6% de proteína bruta tiveram desenvolvimento similar entre si, menor crescimento heterogêneo e não apresentaram deformações, o que demonstra que essas rações são mais adequadas do que a primeira. A ração com 22,5% de proteína bruta mostrou-se inadequada às necessidades dos girinos, o que provocou a exclusão dessa condição, antes do término do experimento, a fim de preservar o bem estar dos animais.Termos para indexação: Rana catesbeiana, nutrição animal, proteína bruta. Heterogeneous growth of bullfrog tadpoles fed with different dietsAbstract -This work tested the performance and growth variability (heterogeneous growth) of Rana catesbeiana tadpoles fed with isocaloric food constituted of four levels of crude protein: three experimental levels (33.6%, 26.6% and 22.5%), and one commercial feed (46.5%). The tadpoles were kept, during three months, in containers with capacity for 1,000 L supplied with running water at density of one tadpole L -1 . The tadpoles were fed twice a day with ad libitum portions, and submitted to the body weight records every fifteen days. The group fed with commercial food (46.5% crude protein) showed better biomassa performance, however the heterogeneous growth was elevated, with body member's deformations in some individuals (27% of tadpoles of the total tadpoleinitiated metamorphosis, and 5% at the end). Tadpoles fed with 33.6% and 26.6% of crude protein had similar growth, less heterogeneous growth and did not show body deformations, indicating that these protein concentration might be more adequate than the commercial one. Food with 22.5% of crude protein showed to be inadequate for the nutritional needing of the tadpoles, so it was excluded from the experiment, in order to preserve the animals from injury and death.