The objective of this trial was to evaluate intake, digestibility, and growth performance of Girolando bulls submitted to two nutritional planes while grazing on Brachiaria brizantha cv. Marandu pasture. Twenty-two animals, with average initial body weight = 209.1 ± 8.2 kg, were used in this trial. The experimental design was repeated measurements, in a 2 × 3 factorial arrangement, with two nutritional planes (NP1 and NP2) and three seasons of the year, with 11 replicates per treatment. The animals of the NP1 received mineral mixture ad libitum during rainy season 1 (15 February through 5 July 2014), energy protein supplement in the amount of 1 g d kg BW-1 during the dry season (from 6 July through 22 November 2014), and again mineral mixture ad libitum during rainy season 2 (from 23 November 2014 through 9 March 2015). The NP2 animals received 2 g d kg BW-1, 2 g d kg BW-1, and 1 g d kg BW-1 of energy-protein supplement in the respective seasons of the year. Forage intakes were similar between nutritional planes, 6.8 and 7.6 kg DM day-1 and 2.1 and 2.22% BW for NP1 and NP2, respectively. There was no statistical difference (level) between the intakes of neutral detergent fiber corrected for ash and protein (4.1 and 4.3 kg day-1 and 1.2 and 1.3% BW, respectively for nutritional planes 1 and 2). For the other nutrients, NP2 showed greater values. The highest intakes and digestibilities of dry matter, organic matter, and non-fiber carbohydrate were in rainy season 2. Performance and feed conversion were similar among NPs. This study showed that lower levels of supplementation could be done in order to reduce feeding costs with no impact on performance.
Keywords: Brachiaria brizantha; Cattle; Nutritional planes; Weight gain.