Increased nitrogen fertilization of marandu grass and protein supplementation: herbage intake, feeding behavior and digestion of nellore heifers

This study aimed to evaluate the efficiency of increased nitrogen via supplementation or fertilization in Marandu-grass pastures on the productive performance of Nellore heifers. The experiment was conducted in an area dominated by Brachiaria brizantha ‘Marandu’. Animals were randomly distributed in 16 paddocks of 0.6 ha under continuous stocking in a completely randomized design, with four repetitions and a 2 × 2 factorial design, with two doses of nitrogen and two types of supplements. This study evaluated animal performance, nutrient digestibility and intake, mean daily weight gain, feed conversion, and the levels of urea in blood plasma. An interaction between nitrogen fertilization and protein supplementation was observed for the parameters herbage intake and coefficient of crude protein digestibility and the levels of urea in the blood plasma, in which higher values were obtained for the combination of pastures fertilized and supplemented. Daily mean gain (P ≤ 0,05) was superior for animals that received supplementation. The results show positive effects of nitrogen fertilization in pasture, maximizing the production efficiency of Nellore heifers raised on pasture. Satisfactory effects were obtained from the protein supplement used on the animals under pasture.