The objective of this study was to evaluate the nutritional status of grazing nursing young bulls supplemented with concentrates with different protein levels during the rainy-dry season transition. Fifty two crossbred Nellore calves with initial mean age of 130 days were divided into four lots, housed in paddocks of Brachiaria decumbens Stapf and received one of the four different supplementation strategies: three different concentrate supplements, or mineral salt (control). The levels of protein in the concentrate supplements varied. After 45 days, the nutritional evaluation of animals, which included the prediction of intake and digestion of nutrients and characteristics of protein metabolism, was made. The prediction of intake and digestibility used the indicators LIPE®, titanium dioxide and neutral detergent fiber indigestible. Urine and blood samples were collected too. The supplementation effect, and the linear and quadratic effects of the level of protein in the concentrate were evaluated by the decomposition of the sum of squares into orthogonal contrasts, adopting α = 0.10. The concentrate intake replaced part of the pasture ingested by the calves and increased protein intake, the digestibility of dry and organic matter, the total digestible nutrients content, and the nitrogen excretion in urine. The level of protein in the supplement has a positive linear effect on the daily protein intake, the digestibility of all nutrients and the total digestible nutrients content, and quadratic effect on the excretion of nitrogen as urea in the urine.
beef cattle; calves; digestibility; intake
