ABSTRACT. The objective of this study was to evaluate productive, nutritional, and economic traits in lactating cows on pasture fed diets with different cation-anion balances (DCAB). Ten lactating – Holstein × ¼ Dairy Gyr cows in the middle third of lactation, at an average age of 70 ± 4.6 months and an average body weight of 400 ± 55.2 kg, were distributed into five treatments in a 5 × 5 Latin square experimental design with two simultaneous squares. Treatments consisted of diets with DCAB of +237, +258, +294, +347, or +419 mEq dry matter (DM). No effects of intake were observed. There was no significant effect of DCAB on milk yield. The milk protein content was not influenced by the DCAB. Body condition score was not significantly affected by the DCAB. The apparent digestibilities of dry matter and nutrients (crude protein, neutral detergent fiber, ether extract, non-fibrous carbohydrates, and total digestible nutrients) were not affected by the DCAB. Marginal rate of return did not show significant differences. Under good conditions of pasture, forage availability, and quality associated with the lactation phases of the cows, all diets were efficient in milk production, dry matter intake, and digestibility. However, in economic terms, the most attractive DCAB was +237 mEq kg-1 DM.

RESUMO. Objetivou-se avaliar correlações entre variáveis produtivas e econômicas em vacas lactantes em pastagem tropical. Foram utilizadas 10 vacas lactantes (– Holandesa x ¼ Gir Leiteiro), no terço médio de lactação, com idade média de 70 ± 4,6 meses e peso corporal médio de 400 ± 55,2 kg. Estes animais foram suplementados com ração concentrada com diferentes composições do suplemento, visando promover alterações na resposta animal e econômica. Os dados foram analisados estatisticamente por meio de correlações lineares de Pearson a 0,95 de probabilidade. Não foram observadas correlações entre gordura e extrato seco total com as variáveis econômicas (p > 0,05). A produção de leite correlacionou-se positivamente com RBVL e RMCS (p < 0,05). A produção de leite não se correlacionou com o CALI e TRM (p > 0,05). Houve ausência de correlações entre produção de leite corrigida e CVOL, CALI e TRM (p > 0,05). Foram observadas correlações positivas entre produção de leite corrigida com RBVL e RMCS (p < 0,05). Houve correlações positivas entre produção de gordura (kg dia-1) com RBVL e RMCS (p < 0,05). A receita bruta com a venda do leite e a receita menos custo com alimentação demonstraram estar altamente associadas com as variáveis produtivas.

ABSTRACT. The objective of this study was to evaluate correlations between production and economic variables of lactating cows on a tropical pasture. The experiment involved ten – Holstein × ¼ Dairy Gyr cows in the middle third of lactation at an average age of 70 ± 4.6 months and an average body weight of 400 ± 55.2 kg. Cows were supplemented with a concentrate feed with different supplement compositions aiming to promote alterations in the animal performance and economic responses. Data were analyzed statistically by Pearson correlations at the 0.95 probability level. No correlations were observed for fat and total solids with economic variables (p > 0.05). Milk yield was positively correlated with (p < 0.05), but had no correlation with FC or MRR (p > 0.05). There were no correlations for milk yield with RC, FC, or MRR (p > 0.05). Positive correlations were observed for fat corrected milk yield with GRSM and RMSC (p < 0.05). Fat production (kg day‒1) was positively correlated with GRSM and RMSC (p < 0.05). The gross revenue from the sale of milk and the revenue minus feed costs showed to be highly associated with production variables.

RESUMO: Palma forrageira foi usada como fonte de nutrientes para a produção de enzimas celulolíticas durante a fermentação em estado sólido com auxílio dos fungos filamentosos Aspergillus niger e Rhizopus sp. Os efeitos da ativiade de água, do tempo de fermentação e da temperatura sobre a produção enzimática foram determinados segundo o protocolo padrão de Delineamento Box-Behnken. A condição ideal para produção das enzimas endoglucanase pelo fungo Aspergillus niger foi 70,35 h de fermentação, atividade de água de 0,875 e temperatura de 29,56 ° C enquanto que para o fungo Rhizopus sp. foi 68,12 h e 30,41 ° C. Entretanto, a celulase total produzida pelo fungo Rhizopus sp. foi otimizada em 74,27 h de fermentação e temperatura de 31,22 ° C e para o fungo Aspergillus niger foi 72,48 h e 27,86 ° C. A atividade de água só tinha uma influência significativa sobre a endoglucanase para Aspergillus niger. A alta estabilidade dos extratos enzimáticos em diferentes tepenraturas e pH's foram confirmadas após caracterização enzimática, indicando viabilidade em aplicações industriais. Os ensaios de desativação cinética indicaram que essas enzimas permaneceram ativas após o congelamento do extrato bruto. Com base nos resultados, utilizar a palma forrageira com matéria prima em bioprocessos é uma alternativa excelente para a produção de enzimas termoestaveis.

ABSTRACT: 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.

The objective of this study was to evaluate the economic returns of crossbred calves grazing on pastures formed by Urochloa brizantha fed crude glycerin as a supplement. Thirty-six crossbred calves with initial average weight of 301.5 kg were distributed in a completely randomized design with four treatments and nine replicates per treatment. The animals were maintained on rotational grazing production of Urochloa brizantha cv. Marandu. The tested treatments were 0.0, 3.33, 6.66 and 9.99% inclusion of crude glycerin in the total dry matter as a substitute for corn. The production of meat was not altered by the inclusion of glycerin in the diet. The inclusion of glycerin caused a reduction of up to 14.93% in the price of the concentrate. There was a significant increase in the total balance, which rose from 3.76 to 91.89 R$/ha with the inclusion of glycerin. The inclusion of crude glycerin in the supplement was capable of raising the net present value and the internal rate of return, proving to be an alternative to reduce the cost of production of supplemented pastured animals.

O objetivo deste trabalho foi avaliar a densidade populacional de perfilhos de pastos de Urochroa decumbens diferidos por 95 e 140 dias, visando determinar a estratégia mais adequada de adubação nitrogenada. Foram estudadas quatro estratégias de adubação no início e no final do verão (0-0, 100-0, 50-50, 0-100 kg ha-1 de N), respectivamente, com quatro repetições. Para os pastos diferidos por 95 dias, as densidades populacionais de perfilhos vegetativos foram maiores (p < 0,05) para a estratégia 0-100. O peso de perfilhos vegetativos por ha, no final do período de diferimento, foi maior para a estratégia 0-100, seguida da estratégia 50-50. As densidades de perfilhos vegetativos, avaliadas nos pastos diferidos por 140 dias, foram maiores (p < 0,05) para as estratégias de adubação 0-100 e parcelados 50-50. No final do período de diferimento, constatou-se maior (p < 0,05) densidade de perfilhos mortos para a estratégia de adubação 0-100, não constatando efeito (p < 0,05) no pós-pastejo. A estratégia de aplicação de 100 kg ha-1 no final do verão, seguida da estratégia de 50 kg ha-1 de nitrogênio parcelado no início e final do verão, promove influência positiva sobre a densidade populacional de perfilhos em pastos diferidos por 140 dias.

The objective of this work was to evaluate the tiller population density in Urochroa decumbens pasture deferred for 95 and 140 days, aiming to determine the best strategy for nitrogen fertilization. Four fertilization strategies at the beginning and end of summer (0-0, 100-0, 50-50, 0-100 kg ha-1 of N) were studied, respectively, with four repetitions. For the pastures deferred for 95 days, the population densities of vegetative tillers were greater (p < 0.05) for the strategy 0-100. At the end of the deferment period, the weight of the vegetative tillers per hectare was greater for the strategy 0-100, followed by the strategy 50-50. The densities of vegetative tillers, evaluated in the pastures deferred for 140 days, were greater (p < 0.05) for the fertilization strategies 0-100 and divided 50-50. At the end of the deferment period, greater density (p < 0.05) of dead tillers was verified for the fertilization strategy 0-100, not proving effect (p < 0.05) in post-grazing. The strategy of application of 100 kg ha-1 at the end of summer, followed by the strategy of 50 kg ha-1 of nitrogen divided between the beginning and end of summer, promoted a positive influence on the tiller population density in pastures deferred for 140 days.

The objective of this study was to evaluate the nutritional and productive characteristics of primiparous lactating cows grazing on tropical pasture, using different levels of crude glycerin in the supplement. The experiment was conducted at Rancho Santana farm, located in Jequié city, Bahia, Brazil, in the period from December 21, 2010 to March 16, 2011. Ten ¾ Holstein × ¼ Dairy Gyr lactating primiparous cows, with 109±24 days of lactation and a mean age of 30±6 months and mean body weight of 426.2±68.29 kg were distributed into five treatments, using two simultaneous 5 × 5 latin squares. Treatments consisted of inclusion levels (0, 94, 191, 289, 389 g/kg dry matter basis) of crude glycerin in the supplement. Intake, digestibility, milk production and composition were measured. Results were statistically analyzed by analysis of variance and regression at 0.05 probability. For all consumption variables no significant differences were found between the levels of crude glycerin. Except for the digestibility of ether extract, all digestibility values were similar between treatments. The fat content and yield showed quadratic effect between treatments. No significant differences were observed for protein, lactose, total solids, nonfat dry extract, fat:protein ratio, milk urea nitrogen and somatic cell count between treatments. For primiparous lactating cows grazing on tropical pasture, up to 389 g of crude glycerin/kg of dietary supplement can be included without nutritional and productive interference.

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.

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.