Diurnal ingestive behaviour of steers grazing Alexander grass with various levels of nitrogen and feed supplements

Abstract

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.

Keywords: Feeding time, grazing, idle, nitrogen fertilization, rumination