The objective of this study was to evaluate the replacement of giant forage cactus (Opuntia ficus indica Mill) by small forage cactus (Nopalea cochenillifera) in diets for growing cattle on the nutrient intake and digestibility. Two incubation periods were also assessed (144 and 288 hours) to obtain the indigestible fractions of dry matter, neutral detergent fiber and acid detergent fiber. Five Holstein heifers were used, approximately 220 kg initial weight placed in a 5 × 5 Latin square design and housed in individual covered, stalls with concrete floor and equipped with masonry feeders and individual drinkers. The experimental diets were based on forage cactus, sugarcane bagasse, soybean meal, urea and mineral mixture, at the proportion of 38.0, 42.0, 18.0, 0.5 and 1.5%, respectively, on dry matter bases, with 0, 25, 50, 75 and 100% of replacement of giant forage cactus by small forage cactus. The intakes and digestibility coefficients of dry matter, organic matter, crude protein, ether extract, total digestible nutrients, total carbohydrates, non-fiber-carbohydrates and neutral detergent fiber were not affected by the replacement. The indigestible dry matter (incubated for 144 hours), indigestible neutral and acid detergent fiber (incubated for 288 hours) made possible to estimate the fecal dry matter production and the dry matter digestibility similar to the total feces collection. The small forage cactus can fully replace the giant forage cactus and the indigestible dry matter incubated for 144 hours and the indigestibles neutral and acid detergent fiber incubated for 288 hours can be used in a digestibility study with ruminants.
digestibility; incubation time; intake
