Given the increasing availability of new cultivars with high yield potential, the use of annual tropical forages to improve cattle production systems is increasing and therefore warrants more research. The objective of this study was to quantify the influence of feed supplementation and nitrogen fertilization on the diurnal ingestive behaviour of crossbred steers (zebu x taurine), maintained on a pasture of Alexander grass (Urochloa plantaginea). The treatments included the application of nitrogen fertilizer at 100 kg/ha; at 100 kg/ha + supplemented feed of wheat bran (0.5% of bodyweight); and at 200 kg/ha. The study used a completely randomized design with three replications. The paddock size was 0.7 ha. Data were analysed by fitting mixed models. The times spent resting, ruminating and consuming water were not different among treatments. However, time spent grazing significantly differed. On average, steers given supplemented feed spent less time grazing (297 min/day) than steers without the supplemented feed (345 min/day). Steers in the pasture with supplementation showed a significantly greater number of daytime bites (2029 bites) than steers in the 200 kg nitrogen treatment (1715 bites). Supplementation reduced grazing time without altering other behaviour variables. The number of daily bites was lower on the pasture with the higher nitrogen level.

O objetivo deste estudo foi avaliar o desempenho de bezerros recebendo ou não suplemento energético, mantidos em pastagem de aveia preta (Avena strigosa Schreb) manejada sob duas ofertas de forragem. Foram utilizados 16 animais do grupamento genético Composto Marchangus Z (1/4 Marchigiana 1/4 Angus 1/2 Nelore), com oito meses de idade, castrados, e com peso médio inicial de 200kg. O delineamento experimental utilizado foi o inteiramente ao acaso, em um fatorial 2x2 (duas ofertas de forragem x dois manejos alimentares - com e sem suplementação de milho moído). Não houve interação significativa entre oferta e suplementação para nenhuma das variáveis. A oferta de forragem real ficou próxima do estipulado para 6 e 10% (5,95% e 9,07%, respectivamente). A oferta de 6% apresentou maior porcentagem de folha (57,0 contra 30,4%), menor porcentagem de colmo (43,0 contra 69,6%) e, consequentemente, maior relação folha/colmo (1,45 contra 0,45), resultando em pastagens de melhor qualidade (PB = 20,0 contra 13,6%) na menor oferta. A taxa de acúmulo diária foi maior (P<0,05) para oferta de forragem de 6% (34,2kg de MS/ha/dia) em relação à oferta de 10% (28,1kg de MS/ha/dia). A suplementação proporcionou maior ganho de peso médio diário (0,749 contra 0,594kg/dia) na recria de bezerros em pastagem de aveia preta IPR-61.

The objective of this study was to evaluate the performance of calves fed supplemented energy or not maintained in oat (Avena strigosa Schreb) managed under two forage allowances. Sixteen Marchangus (1/4 Marchigiana 1/4 Angus 1/2 Nelore) animals were used at eight months old and average initial weight of 200kg. The experimental design utilized was completely randomized in a 2x2 factorial (two forage allowances x two feeding - with and without supplementation of corn). There was no significant interaction between supply and supplementation for the variables. The real forage allowance was close to the expected from 6 to 10% (5.95 and 9.07%, respectively). The offer of 6% shows higher percentage of leaf (57.0 versus 30.4%), lower percentage of stem (43.0 versus 69.6%) and, consequently, higher leaf/stem ratio (1.45 versus 0.45), resulting in better forage (PB=20.0 versus 13.6%), in lower offer. The accumulated rate was higher (P<.05) for forage allowance of 6% (34.2kg of MS/ha/day) in relation to the offer of 10% (28,1kg of MS/ha/day). Supplemented animals showed higher average dairy weight (.749 versus .549kg/day).