Forage productivity and chemical composition of Panicum maximum cv. Mombaça under defoliations intensities and frequencies

Newton De Lucena Costa,Braz Henrique Nunes Rodrigues,Liana Jank,Francisco José De Seixas Santos,Amaury Burlamaqui Bendahan,João Avelar Magalhães

doi:10.33448/rsd-v10i8.17494

Abstract

The effects of defoliation frequency (28, 35, 42 and 49 days) and defoliation intensity (30, 40 and 50 cm above the ground) on green dry matter (GDM) yield, and chemical composition of Panicum maximum cv. Mombaça were evaluated under natural field conditions at the Roraima´s savannas. Defoliation regimes affect productivity and chemical composition of grass forage. The decrease in the pasture defoliation frequency and intensity improved the accumulation of forage, however it reduces the tissue concentrations of N, P, Ca, Mg and K. Irrespective of defoliation frequencies, the highest levels of N (23.99 g kg-1), P (2.12 g kg-1), Ca (4.22 g kg-1), Mg (2.87 g kg-1) and K (21.45 g kg-1) were recorded for the defoliation intensity at 40 cm above the ground. The use of defoliation frequency around 42 days and defoliation intensity of 42,9 cm above the ground can be considered adequate for the management of pastures of P. maximum cv. Mombaça, in order to provides higher forage productivity and quality, regrowth vigor, larger efficiency of forage utilization, greater tissue renewal and canopy structure more favorable to grazing.

Highlights

In Roraima, cattle ranching is one of the most important economic activities in social, economic and environmental terms, and cultivated pastures represent the main forage resource for feeding herds (Costa et al, 2007)
In order to estimate the response of the parameters evaluated to the defoliation frequency and intensity, the choice of regression models was reasoned on the significance of the linear and quadratic coefficients, using the Student's “t”test, at the level of 5% probability
The effect of the defoliation intensity was adjusted to the quadratic regression model (Y = 3,581 + 359.26 X - 4.1827 X2 [R2 = 0.91]) and the maximum value was estimated at 42.9 cm above the ground (Table 1)

Summary

Introduction

In Roraima, cattle ranching is one of the most important economic activities in social, economic and environmental terms, and cultivated pastures represent the main forage resource for feeding herds (Costa et al, 2007). The use of continuous stocking combined with minimum rest periods, and high defoliation intensities are management practices that contribute to low availability and quality of forage, with negative effects on the zootechnical performance indexes of the animals (Costa et al, 2007; Alexandrino et al, 2011). Environmental conditions (temperature, light, water and soil fertility) and management practices significantly affect forage pasture productivity, while its longevity and persistense, among other factors, are consequence from the ability to reconstitute its leaf area after defoliation, which affects the structure of the canopy, determines growth speed, forage accumulation, chemical composition and persistence (Alexandrino et al, 2005; Nabinger & Pontes, 2002; Oliveira et al 2009).

Methodology

Results and Discussion

Final Considerations