Intake, total and partial digestibility of nutrients, and ruminal kinetics in crossbreed steers fed with multiple supplements containing spineless cactus enriched with urea

Abstract

Multiple supplements are used in pasture-based systems to manage deficits in the forage, and they can be composed of a controller mixture (e.g. urea+mineral mixture) to regulate the intake of the animals. The effect of using spineless cactus enriched with urea in place of traditional multiple supplements was evaluated for nutrient intake, partial and total digestibility, and ruminal kinetics in crossbred steers. Five steers, 1/2 Holstein x Zebu, with permanent cannulas in the rumen and with an average initial body weight of 240±22.1kg, were used in a 5×5 Latin square. The treatments consisted of four levels of inclusion of urea (0%, 1%, 2%, and 3%) in dry matter (DM) and a control treatment with a traditional multiple supplement. The Tifton-85 hay, used as forage, had high neutral detergent fiber (659g NDF kg−1 of DM) and low crude protein (62g CP kg−1 of DM) content. There was a linear increase in the intake of CP and a quadratic effect in intake of dry matter (DM), organic matter (OM), non-fiber carbohydrates (NFC), NDF, and digestible OM according to the urea inclusion level. The maximum point for total OM digestibility (645gkg−1) was with the inclusion of 2% urea. There was an improvement in ruminal digestibility of DM, NDF, and CP when spineless cactus was enriched with urea. The ruminal pool of DM, NDF, and iNDF did not change with the inclusion of urea in the diets. Increased intake rate (ki) was observed when spineless cactus was enriched with urea. The passage rate (kp) of spineless cactus enriched with 3% urea was similar to the control diet. The rate of NDF degradation increased in the diets enriched with spineless cactus. It is suggested that spineless cactus enriched with up to 2% urea efficiently replaces traditional multiple supplements.