Background: There is a comprehensive understanding of the role of dietary fiber as a nutrient and its function during digestion in cattle. On the other hand, the role of fiber digestion in goats has not received similar attention. Objective: To evaluate the effects of different ratios of forage neutral detergent fiber (fNDF) and non-fibrous carbohydrates (NFC) on ruminal fermentation products, and in vitro neutral detergent fiber (NDF) digestibility in goats. Methods: A 3 × 5 factorial arrangement in a completely randomized design with three fNDF levels (100, 190, and 290 g/kg) and five NFC levels (350, 400, 450, 500, and 550 g/kg) was used. The experiment was performed in vitro. Two ruminally fistulated goats were used as rumen liquid donors. Results: The ratios between fNDF and NFC affected all ruminal parameters (p<0.05). Increasing NFC levels in diets containing 100 and 290 g/kgfNDF resulted in linear increase (p<0.05) in ammonia concentration after 48 h fermentation. There was no adjustment of linear models (p>0.05) for pH values. Total volatile fatty acids (VFA) and their individual molar proportions were affected (p<0.05) at all fNDF and NFC levels. The NDF digestibility was not affected (p>0.05) by fNDF or NFC levels, except for diets containing 290 g/kg fNDF, which were fit to a quadratic model (p<0.05). Conclusion: The relationship between fNDF and NFC concentrations affect the fermentation end products and in vitro NDF digestibility. NFC plays a more consistent role than fNDF in the ruminal microbial ecosystem of goats during in vitro fermentation.Keywords: digestion, energy, microbial protein, physically effective fiber, rumen. Resumen Antecedentes: Aunque hay una amplia comprensión del papel que juega la fibra dietética como nutriente y su función durante la digestión en el ganado vacuno, el papel de la digestión de la fibra en las cabras no ha recibido una atención similar. Objetivo: Evaluar los efectos de diferentes proporciones de fibra detergente neutra proveniente del forraje (fNDF) y carbohidratos no fibrosos (NFC) sobre los productos de la fermentación ruminal y la digestibilidad in vitro de la fibra detergente neutra (NDF) en cabras. Métodos: Se utilizó un arreglo factorial de 3 × 5, distribuidos en un diseño completamente aleatorizado con tres niveles de fNDF (100, 190 y 290 g/kg) y cinco niveles de NFC (350, 400, 450, 500 y 550 g/kg). El experimento se realizó in vitro. Se utilizaron dos cabras fistuladas en rumen como donantes de líquido ruminal. Resultados: La relacion entre fNDF y NFC afectó todos los parámetros ruminales estudiados (p<0,05). El aumento de los niveles de NFC en dietas con 100 y 290 g/kg de fNDF resultó en aumento lineal (p<0,05) de la concentración de amoníaco después de 48 h de fermentación. No hubo ajuste de modelos lineales (p>0,05) para valores de pH. Los ácidos grasos volátiles totales y sus proporciones molares individuales se afectaron (p<0,05) en todos los niveles de fNDF y NFC. La digestibilidad de NDF no fue afectada (p>0,05) por los niveles de fNDF ni NFC, con excepción de las dietas con 290 g/kg fNDF, que se ajustaron a un modelo cuadrático (p<0,05). Conclusión: La relación entre las concentraciones de fNDF y NFC afecta los productos finales de fermentación y la digestibilidad in vitro de NDF. Los niveles de NFC juegan un papel más consistente que fNDF en el ecosistema microbiano ruminal de la cabra durante la fermentación in vitro.Palabras clave: digestión, energía, fibra físicamente efectiva, proteína microbiana, rumen. ResumoAntecedentes: Embora exista um compreensível entendimento do papel que a fibra dietética desempenha como nutriente e sua função durante a digestão em bovinos, o papel da digestão das fibras em caprinos não recebeu atenção semelhante. Objetivo: Avaliar os efeitos de diferentes relações da fibra em detergente neutro advindo de forragem (fNDF) e carboidratos não-fibrosos (NFC) sobre produtos da fermentação ruminal e digestibilidade in vitro da fibra em detergente neutro (NDF) em caprinos. Métodos: Utilizou-se um esquema fatorial de 3 × 5 distribuídos em um delineamento inteiramente casualizado com três níveis de fNDF (100, 190 e 290 g/kg) e cinco níveis de NFC (350, 400, 450, 500 e 550 g/kg). O experimento foi realizado in vitro. Duas cabras fistuladas no rúmen foram utilizadas como doadoras de líquido ruminal. Resultados: As relações entre fNDF e NFC impactaram todos os parâmetros ruminais estudados (p<0,05). O aumento dos níveis de NFC em dietas contendo 100 e 290 g/kg de fNDF resultou em um aumento linear (p<0,05) na concentração de amônia após 48 h de fermentação. Não houve ajuste de modelos lineares (p>0,05) para valores de pH. Os ácidos graxos voláteis totais e suas proporções molares individuais foram afetados (p<0,05) em todos os níveis de fNDF e NFC. A digestibilidade NDF não foi afetada (p>0,05) pelos níveis de fNDF e NFC, com exceção de dietas experimentais contendo 290 g/kg fNDF, que foram ajustadas a um modelo quadrático (p<0,05). Conclusão: A relação entre as concentrações de fNDF e NFC afeta os produtos finais de fermentação e a digestibilidade in vitro de NDF de dietas experimentais. Os níveis de NFC desempenham um papel mais consistente do que o fNDF no ecossistema microbiano ruminal de cabras durante a fermentação in vitro.Palavras-chave: digestão, energia, fibra fisicamente efetiva, proteína microbiana, rúmen.

No abstract

We evaluated the effects of urea addition on gas and effluent losses, fermentation profile, microbial populations, aerobic stability and chemical composition of corn silages. A completely randomised design with five levels of urea (0, 0.5, 1.0, 1.5, and 2.0% based on dry matter) and five replicates was used. A decreasing linear effect of urea levels on effluent losses in corn silages was observed. In parallel, an increasing linear effect of urea levels on pH, increasing from 3.49 to 4.12 in silages without urea in relation to silages with the maximum urea level, was also observed. Urea addition improved the aerobic stability of the silages, with 62 h for the silages without urea and from 90 to >96 h for the silages with urea. Based on the results of the principal components, two groups (I and II) could be distinguished. The most discriminating variables in group I were dry matter (-0.9), pH (-1.2) and lactic acid bacteria (-0.9), while in group II, effluent losses (1.0), ethanol (1.0), acetic acid (0.8) and gas losses (0.8) were most important. The use of urea at inclusion levels of around 2% in corn silage reduced gas losses, improved the nutritive value and promote the aerobic stability of silages. Highlights: The addition of urea in the corn silages increased the pH values from 3.49 (control) to 4.12 (2% of urea DM). The use of urea improved chemical composition of corn silages. The addition of urea reduced the moulds and yeast populations in the corn silages after exposure to air. Urea addition improved the aerobic stability of the corn silages.

505Effect of spineless-cactus mucilage on the in vitro rumen fermentation of cellulose, starch, and proteinEfeito da mucilagem da palma forrageira sobre a fermentação ruminal in vitro da celulose, amido e proteína

The effect of diets containing 0% of wheat bran levels (control buffel grass and cactus pear) contrasted with diets with cactus pear as the only forage source and wheat bran levels (30; 37 and 44%) on nutrient digestibility, feed intake, animal performance, carcass characteristics, and economic analysis was evaluated. Twenty-eight male, non-castrated crossbred lambs (22.6 ± 2.37 kg) were submitted to confinement for 62 days. A completely randomized design was used with four treatments and seven repetitions. Four diets were formulated considering an intended mean daily weight gain of 200 g/animal/day. Means were compared by contrasts using Dunnett test at 5%. Animals fed cactus pear as the only roughage source (diets with 30; 37, and 44% of wheat bran) had lower dry matter intake and nutrient intake, Average Dairy Gain, and total weight gain than animals fed the control diet. Final body weight and slaughter weight of animals fed 44% of wheat bran was similar to the animals fed the control diet. Hot and cold carcass yields were higher in animals fed cactus pear and 30 and 37% of wheat bran. Feeding costs were lower when cactus pear was used as the only roughage source associated with wheat bran and consequently profit was greater. The use of cactus pear as the only roughage source associated with up to 44% of wheat bran is a viable alternative of the diet to confined lambs without modifying carcass characteristics with greater cost:benefit ratio.