Performance, digestibility and nitrogen balance of Nellore cattle reared in different intensified production systems

Abstract

Because of the massive participation of beef cattle in the economy, the environmental impacts of ruminant production on the planet have been the focus of discussions in the scientific environment, searching for solutions to improve animal production and save resources and land, which has been the main challenges. For the animal science community. Thus, the present study aims to evaluate the effect of intensification of production systems on the digestibility and nitrogen balance of Nellore cattle reared in Marandu palisadegrass pasture, managed under continuous stocking and receiving different doses of nitrogen fertilization. The experiment will be conducted in the Beef Cattle Laboratory of the Department of Animal Science of the Paulista State University "Júlio de Mesquita Filho" (UNESP), Jaboticabal campus. The area has 24 hectares split into 12 paddocks of approximately 2 ha each. The grazing method will be continuous stocking and variable stocking rate to keep the canopy height at 25 cm. The treatments will be different intensification levels: low (0 kg N ha-1 year-1 and 1.5AU ha-1; AU = animal unit, 450 kg body weight), intermediate (75 kg N and 3.0AU ha-1) and high (150 kg N and 4.5AU ha-1). The fertilization will be with ammonium nitrate (32% N), which will be fractionated in three doses of the same amount. Assessments of intake, digestibility and urinary excretion will be performed in eight test animals per treatment, one per animal during the rearing phase. (AU)