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The objective of this work was to evaluate the effects of different levels of sugarcane bagasse, as exclusive roughage, on nutrient intake and digestibility, feeding behavior, microbial protein synthesis, and dairy performance of crossbred cows. Ten lactating Girolando breed cows (600±34.3 kg body weight) were assigned to a replicated 5×5 Latin square design. The control diet, based on spineless cactus, sugarcane bagasse, and concentrate, was formulated to meet the average production of 20 kg of milk per day, with 3.5% fat. The evaluated levels of sugarcane bagasse were: 30, 38, 46, and 54% dry matter bases. The intake and digestibility of dry matter decreased linearly with sugarcane bagasse levels. Rumination time was higher in cows fed 54% sugarcane bagasse. The inclusion levels had no effect on non-esterified fatty acid contents or on the efficiency of microbial protein synthesis, but beta-hydroxybutyrate concentrations showed a quadratic pattern to the bagasse levels. Higher yields of 3.5% fat-corrected milk were obtained with cows fed 30% sugarcane bagasse. Sugarcane bagasse inclusion in the diet of crossbred dairy cows decreases their performance; however, the bagasse can be used as exclusive roughage when associated with 70% concentrate.

<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>

The objective of this study was to evaluate the nutritional value of different roughage sources as an exclusive feed for goats and sheep from the determination of nutrient intake and digestibility. Five goats and five sheep were used and arranged in a double 5 × 5 Latin square design. Treatments consisted of cactus Nopalea cochenillifera (L.) Salm-Dyck cladodes ( Nopalea ) + urea + sugarcane bagasse (NUB), cactus Opuntia stricta (Haw.) Haw cladodes ( Opuntia ) + urea + sugarcane bagasse (OUB), Tifton hay (TH), maize silage (MS), and forage sorghum silage (SS). Dry matter (DM) and crude protein (CP) intakes of NUB were greater than SS (0.620 and 0.058 versus 0.416 and 0.040 kg/day). Metabolizable energy (ME) intake was higher for NUB (1.52 Mcal/day). The DM digestibility did not change between the roughages (59%). The NUB, OUB, and MS organic matter digestibility (OMD; 62.4%) were greater than that of SS (57.4%). The roughage consisting of cactus cladodes associated with urea and sugarcane bagasse presented a greater nutritional value, similar to MS and TH, and higher than SS. Cactus cladodes associated with urea and sugarcane bagasse are recommended as an alternative to conserved feed.

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