-Prickly palm cactus husk was used as a solid-state fermentation support substrate for the production of cellulolytic enzymes using Aspergillus niger and Rhizopus sp. A Box-Behnken design was used to evaluate the effects of water activity, fermentation time and temperature on endoglucanase and total cellulase production. Response Surface Methodology showed that optimum conditions for endoglucanase production were achieved at after 70.35 h of fermentation at 29.56°C and a water activity of 0.875 for Aspergillus niger and after 68.12 h at 30.41°C for Rhizopus sp. Optimum conditions for total cellulase production were achieved after 74.27 h of fermentation at 31.22°C for Aspergillus niger and after 72.48 h and 27.86°C for Rhizopus sp. Water activity had a significant effect on Aspergillus niger endoglucanase production only. In industrial applications, enzymatic characterization is important for optimizing variables such as temperature and pH. In this study we showed that endoglucanase and total cellulase had a high level of thermostability and pH stability in all the enzymatic extracts. Enzymatic deactivation kinetic experiments indicated that the enzymes remained active after the freezing of the crude extract. Based on the results, bioconversion of cactus is an excellent alternative for the production of thermostable enzymes.Keywords: Filamentous fungi. Response surface methodology. Bioprocesses. Semi-arid region. Enzymatic characterization. PRODUÇÃO E CARACTERIZAÇÃO DE ENZIMAS CELULOLÍTICAS POR ASPERGILLUS

RESUMO -Objetivou-se avaliar as respostas econômicas de novilhos Nelore em terminação à suplementação em pastagens de Brachiaria brizantha no Sudoeste da Bahia. O experimento foi desenvolvido no período de agosto a novembro de 2006 em uma área de 52,0 hectares, dividida em oito piquetes de aproximadamente 6,5 hectares. Testaram-se quatro níveis de suplementação com concentrado (controle, 0,3; 0,6 e 0,9% do peso vivo do animal) em comparação à suplementação com sal mineral. Os níveis de suplementação elevaram a quantidade de carne produzida por hectare. A curva de crescimento da receita é menos acentuada que a dos custos, o que resulta em achatamento do lucro de acordo com os níveis de suplementação estudados.Os melhores resultados biológicos obtidos com elevados níveis de suplemento não são economicamente sustentáveis, em decorrência do aumento do custo de produção, no entanto, níveis de suplementação inferiores a 0,3% do peso vivo na fase de terminação são viáveis e têm potencial econômico.Palavras-chave: Brachiaria brizantha, produção de carne, sistemas de produção de bovinos Supplementation levels in finishing of Nelore steers on pastures: economic aspectsABSTRACT -In this study, it was aimed to evaluate the economic responses of finishing Nellore steers to supplementation of Brachiaria brizantha pastures in southwestern Bahia. The experiment was developed from August to November 2006 in a 52-ha area divided in eight pickets of approximately 6.5 hectares each. It was tested four levels of concentrate supplementation (control, 0.3, 0.6 and 0.9% of the body weight of animal) compared to supplementation with mineral salt. Supplementation levels raised the amount of meat produced per hectare. The curve of revenue growth is less sharp than the cost growth curve, resulting in a flattening of profit according to levels of the studied supplementation. The best biological results obtained from high levels of supplements are not economically sustainable because of the increase in the production cost, however, supplementation levels lower than 0.3% of body weight in the finishing phase are feasible and they are potentially economical.Key Words: Brachiaria brizantha, meat production, production systems of cattle Revista Brasileira de Zootecnia IntroduçãoA cada ano que passa, o agronegócio brasileiro consolida sua importante posição na economia, como resultado do avanço tecnológico, do incremento na produtividade e da ocupação de novas áreas (Fernandes et al., 2007). Desta maneira, como qualquer atividade do setor pecuário, para se manter competitiva, deve ser constantemente avaliada, principalmente no que tange aos aspectos econômicos. Neste contexto, os custos de produção da atividade, a receita obtida e a rentabilidade do capital investido são fatores importantes para o sucesso de qualquer sistema de produção.A produção de carne no Brasil tem crescido significativamente, observando-se que, a partir de 1990, com a globalização da economia e a abertura dos mercados, intensificou-se ainda mais o processo de modernização ...

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This experiment was designed to evaluate the effects of the inclusion of detoxified castor bean meal (CM) content on the chemical-bromatological composition, as well as the fermentation characteristics and dry matter losses of sugarcane silage. The treatments consisted of four levels (0, 7, 14 and 21% natural matter) of addition of castor bean meal. The design was completely randomized, with five replicates. The material was ensiled in PVC silos of 50-cm in height and 10-cm in diameter, which were opened after 60 days. The density of fodder maintained in the silos was equal to 750kg of natural matter/m 3 . In order to quantify the gas and effluent losses, the silos were weighed at the beginning and at the end of the experiment. The addition of castor bean meal has increased the levels of DM and crude protein and reduced the levels of neutral detergent fiber, N-NH 3 , ethanol, and gas and effluent losses from silages, but did not affect pH values. During ensiling, alcoholic fermentation was controlled with the inclusion of the additive. RESUMOO experimento foi desenvolvido para avaliar os efeitos da inclusão de níveis de farelo de mamona destoxificado sobre a composição químico-bromatológica, as características fermentativas e as perdas de matéria seca da silagem de cana-de-açúcar. Os tratamentos consistiam em quatro níveis (0, 7, 14 e 21% da matéria natural) de inclusão do farelo de mamona. O delineamento foi inteiramente ao acaso, com cinco repetições. Foram usados silos de PVC, com 50cm de altura e 10cm de diâmetro, para a produção das silagens, que foram abertos após 60 dias. A densidade de forragem nos silos foi correspondente a 750kg de matéria natural/m 3 . Os silos foram pesados no início e ao final do período experimental para quantificar as perdas por gases e efluentes. A inclusão de farelo de mamona elevou os teores de MS e proteína bruta e reduziu os teores de fibra em detergente neutro, N-NH 3 , etanol e as perdas por gases e efluentes das silagens, não ocasionando efeito nos valores de pH. A fermentação alcoólica durante a ensilagem foi controlada com a inclusão do aditivo.

The objective of this study was to assess the effect of substituting corn with soybean hulls on the ingestive behavior and nitrogen balance of Santa Ines lambs. A total of 25 lambs with an initial body weight of 20±2 kg at approximately six months of age, sheltered individually in stalls (1.10 m×1.0 m), considering an entirely casual experimental delineation. Soybean hulls were substituted for corn at 0, 250, 500, 750, and 1,000 g/kg of dry matter (DM). The time spent feeding, ruminating, masticating, and resting was not affected by the substitution of corn with soybean hulls. In fact, the feeding efficiency in g DM/h and the rumination efficiency in g DM/bolus increased linearly with soybean hull substitution in the feed. Although the nitrogen balance was not altered by the use of soybean hulls as a substitute for corn in the diets of Santa Ines lambs, the N ingested and N digested expressed in g/d, N retained as a percentage of that ingested, and N retained as a percentage of that digested displayed quadratic behavior. In conclusion, corn can be substituted with soybean hulls up to 1,000 g/kg of dry matter in the concentrate, without changing the ingestive behavior and nitrogen balance.