Grazing height targets for Alexandergrass pastures under continuous stocking in integrated crop-livestock system

André Brugnara Soares,Alceu Luís Assmann,Tangriani Simioni Assmann,Daniel Schmitt,Francisco Migliorini

doi:10.1590/0103-8478cr20180837

André Brugnara Soares, Alceu Luís Assmann + Show 3 more

Open Access

https://doi.org/10.1590/0103-8478cr20180837

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Abstract

ABSTRACT: The aim of this experiment was to identify grazing height targets for Alexandergrass pastures under continuous stocking in integrated crop-livestock system (ICLS). For this purpose, twelve pastures were cultivated into an ICLS area, and maintained at 10, 20, 30, or 40 cm using grazing goats. The following variables were analyzed: leaf and herbage mass, accumulation rate, and allowance; leaf:stem ratio; chemical composition of hand-plucked samples; stocking rate; average daily gain and gain per area. The data were submitted to regression and correlation analysis. Significance was set at 5% (P≤0.05). The main results were: i) herbage and leaf lamina mass increased linearly with grazing height, and pastures maintained at 20 cm already presented the minimum amount recommended for soil cover in ICLS; ii) animal performance achieved an upper asymptotic plateau in pastures maintained around 30-40 cm and it was highly correlated with both grazing height and forage availability (mass and allowance). Alexandergrass pastures under continuous stocking in ICLS should be maintained between 30-40 cm to improve both cover crop biomass and animal performance.

Highlights

Herbage (P
Concerning the values, they were equivalent to that reported for high productive tall-tufted grasses (e.g. Sorghum; RESTLE et al, 2002) or Alexandergrass pastures receiving up to 400 kg N ha-1 (ADAMI et al, 2010); grazing heights around 20 cm already presented the minimum amount of herbage mass for a good soil cover in integrated crop-livestock systems (ICLS) (2000 kg DM ha-1; KUNRATH et al, 2014)
There were no corresponding increases in average daily gain, indicating that the variations in animal performance reported in our experiment may not be related to changes in nutritive value

Summary

Introduction

Alexandergrass (Urochloa [Syn. Brachiaria] plantaginea), popularly known in Brazil as ‘Papuã’, is an annual warm-season grass that growths spontaneously in grain crop fields during the late spring and summer (RESTLE et al, 2002). In areas devoted to integrated crop-livestock systems (ICLS), it can be a low-cost forage alternative, since it presents high levels of herbage production and is available in large quantities at the end of the summer cropping season (ADAMI et al, 2010). Alexandergrass could be used as pasture (NEGRINI et al, 2018), cover crop biomass (BOLLINGER et al, 2006) or stockpiled forage (SILVA et al, 2011), being an interesting alternative for crop rotation planning. A possible explanation may be the lack of applied and low-cost management tools to maximize forage accumulation and animal

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Results