ABSTRACT - The objective of this study was to evaluate the effect of replacing wheat bran by spineless cactus (0, 25, 50, 75, and 100%) in sugar cane-based diets on intake and nutrient digestibility and ruminal parameters of sheep. Five sheep (Santa Inês; average initial weight of 34.0±3.6 kg) were fitted with cannulas in the rumen and then assigned to a 5 × 5 Latin square design. The maximum dry matter (DM; 1414 g d−1), digestible organic matter (658 g d−1), and neutral detergent fiber corrected for ash and protein (NDFap; 425 g d−1) intakes were estimated by replacing 80.2, 89.9, and 50.5% of wheat bran. Dry matter and crude protein digestibility increased by 0.60 and 0.85 g kg-1 of DM. With the replacement of 57.1 and 62.2% of wheat bran, a maximum rate of NDF ingestion (0.70 h−1) and NDF ruminal pool (7.31 g) was obtained. Rumen pH increased with the inclusion of spineless cactus, while the maximum concentration of ammonia N (33.3 mg dL−1) and total volatile fatty acids (57.7 μmol mL−1) were estimated at the levels of 72.3 and 63.7% of replacement of wheat bran. It is recommended to replace 63% of wheat bran by spineless cactus in sugar cane-based diets, to promote better animal performance.

<p>Objetivou-se avaliar o efeito de diferentes proporções de concentrado e bagaço de cana-de-açúcar como volumoso exclusivo em dietas para ovinos. Os consumos de matéria seca, matéria orgânica, proteína bruta, carboidratos não fibrosos e nutrientes digestíveis totais expressos em kg/dia, aumentaram linearmente com o aumento da proporção de concentrado na dieta. O mesmo comportamento foi observado para a digestibilidade da matéria seca. O que ocorreu de forma contrária para a digestibilidade da fibra em detergente neutro, que diminuiu com os maiores níveis de concentrado. Com o aumento das proporções de concentrado nas dietas experimentais, foi observado efeito quadrático no tempo despendido com ruminação, alimentação e ócio, e nas concentrações de ácido acético, propiônico e butírico no rúmen. Maiores proporções de concentrado associado ao bagaço de cana-de-açúcar <italic>in natura</italic>podem ser utilizadas em dietas para ovinos.</p>

<p>This study aimed to evaluate the effect of different proportions of concentrate and sugar cane bagasse as roughage exclusive for sheep. The dry matter intake, organic matter, crude protein, non-fibrous carbohydrates and total digestible nutrients in kg/day, increased linearly with increasing proportion of concentrate in the diet. The same behavior was observed for dry matter digestibility. It occurred in a manner contrary to the digestibility of neutral detergent fiber that decreased with the higher levels of concentrate. With the increase of the proportion of concentrate in the diets, quadratic effect was observed to time of rumination, feeding and idleness, and the of concentrations of acetic, propionic and butyric acid in the rumen. Higher proportions of concentrate associated with sugar cane bagasse <italic>in nature</italic>can be used in diets.</p>