Abstract The present study aimed to evaluate the effect of alkaline treatments with urea, NaOH and Ca(OH)2 on chemical composition and in situ ruminal degradability of dry matter, crud protein and neutral detergent fiber of sugarcane tip hay. Samples were incubated in the rumen of three cannulated cattle for up to 72 hours in a split plot randomized block design. Ammoniation with 6% urea increased (p<0.05) the crude protein content by 13% and reduced the neutral detergent fiber and insoluble nitrogen content of the hay. When treated with the highest doses of the compounds, there was a high potential degradability of dry matter, crude protein and neutral detergent fiber, and a shorter neutral detergent fiber lag time. Ammoniation with urea promotes a reduction in the content of NDF, hemicellulose and insoluble nitrogen, with an increase in the content of CP in the hay, with emphasis for the level of 6% urea. The ruminal degradation of sugarcane tip hay increases with alkaline treatments using 6% urea or 3% NaOH, however, ammoniation with urea is indicated for the treatment of hay, as this is low cost and can be easily adopted by farmers in the semiarid region.

RESUMO Objetivou-se avaliar as características morfogênicas e estruturais e os padrões demográficos do capim-andropógon submetido a diferentes frequências e intensidades de corte. Adotou-se o delineamento inteiramente casualizado em arranjo fatorial 3 x 2, correspondente a três alturas de corte (50, 70 e 90 cm) e duas intensidades de corte (50 e 70%) com quatro repetições, totalizando 24 parcelas de 7,50 x 6,25 m. Para as características morfogênicas houve efeito (p ≤ 0,05) da interação na taxa de alongamento do colmo, taxa de aparecimento de folhas e taxa de filocrono. A maior taxa de alongamento foliar foi observada na altura de 90 cm e intensidade de corte de 50%, apresentando 1,69 e 0,84 cm perfilho-1 d-1 de alongamento foliar nas alturas de 50 e 70 cm, respectivamente. Para produção de forragem não foi verificado efeito da interação (p > 0,05) entre as intensidades de corte e altura de corte. Quando o pasto foi manejado com altura de corte de 90 cm, observou-se maior incremento de massa seca foliar, massa seca de colmo, massa seca de forragem morta e massa seca de forragem total, a qual foi superior em 50,89 e 53,29% em relação às alturas de 50 e 70 cm, respectivamente. Para as características demográficas do capim andropógon não se observou efeito da interação entre os fatores (p > 0,05). Recomenda-se a altura de corte de 70 cm com intensidade de corte de 50% no manejo desta gramínea.

ABSTRACT The objective of this study was to evaluate the morphogenic and structural characteristics, and demographic patterns of Andropogon gayanus subjected to different cutting frequencies and intensities. A completely randomized design was adopted in a 3 × 2 factorial arrangement, corresponding to three cutting heights (50, 70, and 90 cm), and two cutting intensities (50 and 70%) with four repetitions, totaling 24 plots of 7.50 × 6.25 m. For morphogenesis, there was no interaction effect (P ≤ 0.05) of treatments on stem elongation rate, leaf appearance rate, and phyllochron rate. The highest rate of leaf elongation was observed at a height of 90 cm and cut intensity of 50%, with 1.69 and 0.84 cm tiller-1 d-1 of leaf elongation at heights of 50 and 70 cm, respectively. For forage production, there was no interaction (p > 0.05) between cutting intensity and cutting height. When the pasture was managed to a cutting height of 90 cm, there was a greater increase in dry leaf mass, stalk dry mass, dead forage dry mass, and total dry forage mass, which was 50.89% and 53.29% higher than pasture heights of 50 and 70 cm, respectively. There was no interaction between factors on demographic characteristics (p > 0.05). A cutting height of 70 cm with a cutting intensity of 50% is recommended when handling this grass.

This study measured the kinetic parameters of the ruminal degradation of the silage of Brachiaria brizantha cv. Marandu. The experiment had a completely randomized design with five treatments and five repetitions; the treatments featured the inclusión of natural brewer’s grain to Marandu grass silage at levels of 0, 10, 20, 30 and 40%. The regression equation for the degradability of the soluble Fraction A of dry matter showed a linearly increasing pattern (P<0.05) with an addition of 0.19% for each 1% of brewer’s grain included. The percentage of insoluble potentially degradable fraction (B) of dry matter was reduced linearly (P<0.05). The ruminal degradation rate in the dry matter (c), expressed as % h-1, increased linearly (P<0.05). The crude protein percentage in the Fraction B demonstrated a linear regression pattern as brewer’s grains were added (P<0.05), and there was a 0.06% reduction per unit of additive to Marandu grass silage. There was a linear increase in degradation rate c in the crude protein (P<0.05) as the additive was included in the silage. A linear increase (P<0.05) was observed for the regression of the potentially degradable fraction of NDF, represented by Fraction D. The inclusion of 20% of brewer’s grain to Marandu grass silage resulted in an improvement in the kinetic parameters of ruminal degradation.

Este estudio tuvo como objetivo medir los parámetros cinéticos de la degradación ruminal de ensilaje de Brachiaria brizantha cv. Marandu. El experimento se realizó en un diseño completamente al azar con cinco tratamientos y cinco repeticiones, los tratamientos se incluyen granos de cervecería a Marandu ensilado de hierba a niveles de 0, 10, 20, 30 y 40%. Observando la ecuación de regresión de la degradabilidad la Fracción soluble A de la materia seca, había una creciente comportamiento lineal (P<0,05), un aumento de 0,19 unidades porcentuales con la adición de 1% de la fábrica de cerveza en grano ensilado Marandu. El porcentaje de la fracción insoluble potencialmente degradable (B) de la materia seca reducida linealmente (P<0,05). La tasa de degradación ruminal (c), expresada en % h-1 el aumento linealmente (P<0,05). El porcentaje de proteína cruda en la fracción B demuestra un patrón de regresión lineal con la adición de granos de cerveza (P<0,05), hubo una reducción de 0,06% por unidad de aditivo incluido en Marandu ensilado de hierba. Para C velocidad de degradación de proteína cruda, una respuesta lineal (P<0,05), debido a la inclusión de niveles de aditivos en el ensilaje. Hubo aumento lineal (P<0,05) de la ecuación de regresión de potencialmente degradable NDF, representado por la fracción D. La inclusión de 20% de grano de cerveza a Marandu ensilado de hierba resultó en una mejora de los parámetros cinéticos de la degradación ruminal.