Beef cattle performance on signal grass pastures deferred and fertilized with nitrogen

P.L Amorim,J.P.P Rodrigues,C.G Vitor,F.H.M Chizzotti,R.M Pimentel,D.M Fonseca,M.E.R Santos

doi:10.1590/1678-4162-10205

Abstract

ABSTRACT The effect of four nitrogen levels (0, 40, 80 and 120kg N ha-1), applied before deferment on the beef cattle production and structural variables on Urochloa decumbens (signal grass) were assessed from January to October 2012 and from January to September 2013. A randomized block design with three replicates was adopted, in an arrangement of repeated measures in time (grazing period). An interaction effect between nitrogen level and grazing period was observed on extended-plant height and herbage mass. As the nitrogen levels were increased, extended-plant height, herbage mass, total herbage allowance, and efficiency of conversion of fertilizer into herbage were increased. Throughout the grazing period, pasture height, extended-plant height, percentage of leaves, herbage and morphological components allowance, and percentages of leaves and stems in the herbage apparently selected by the animal decreased. Nitrogen levels had no effect on average daily gain or gain per area in the first year. A fixed deferment period with increasing levels of nitrogen fertilization on signal grass pastures does not influence the average daily gain per animal, reduces the efficiency of the nitrogen fertilizer and negatively changes the structural characteristics of the pasture.

Highlights

The deferment is a useful management tool in tropical conditions and consists of removing grazing animals from a given area of the pasture in the final third of the rainy season aiming to produce forage to be grazed on during the dry period and forage scarcity
An interaction effect between nitrogen level and grazing period was observed on extended-plant height and herbage mass
Throughout the grazing period, pasture height, extended-plant height, percentage of leaves, herbage and morphological components allowance, and percentages of leaves and stems in the herbage apparently selected by the animal decreased

Summary

Introduction

The deferment is a useful management tool in tropical conditions and consists of removing grazing animals from a given area of the pasture in the final third of the rainy season aiming to produce forage to be grazed on during the dry period and forage scarcity. Several management actions can be taken in pasture deferment, involving the time, period, and pasture height at the beginning of deferment, supplementation, or nitrogen fertilization, which should all be observed to ensure good results These actions aim to provide deferred pastures with good structural and qualitative characteristics and greater potential to improve animal performance. Greater nitrogen (N) fertilization may negatively affect the structure of the deferred pasture, resulting in an excessive increase in forage mass, forage losses, percentage of stems, dead forage, and reducing the percentage of live leaves, in addition to increasing N losses to the environment. The aim of this study was to evaluate the sward structure and beef cattle production on signal grass pastures fertilized with N levels in the beginning of the deferment period

Objectives

Methods

Results