Defoliation dynamics of Brachiaria brizantha pastures with distinct structural characteristics

Patrick Bezerra Fernandes,Raísa Turcato De Oliveira,Caio Vinicio Vargas De Oliveira,Cauby De Medeiros-Neto,Rodrigo Amorim Barbosa

doi:10.14393/bj-v36n1a2020-42211

Abstract

Although belonging to the same species, different Brachiaria brizantha varieties used for pasture vary significantly in their morphological structure. Therefore, this study starts from the central hypothesis that the defoliation dynamics during the period of occupation by animals in pastures formed by Brachiaria brizantha under rotational stocking varies among cultivars during the year. The experimental design used was randomized blocks with three treatments and three repetitions, with the cultivars consisting of Brachiaria brizantha cv. Xaraés, BRS Paiaguás, and Ecótipo B4. The defoliation patterns during the grazing periods were estimated using the marked tiller technique. Despite alterations in the tiller and forage mass components in the wet and dry seasons, no variations were observed in the tiller defoliation dynamics and the respective structural components. In the wet season, the area grazed only once was greater for BRS Paiaguás compared to the other two cultivars, but the other areas representing the grazing horizons were equally exploited among the grass varieties during the year. Therefore, based on the defoliation dynamics of pastures in Brazil’s tropical climate, it is possible to suggest that pastures formed by grasses with different structures and growth habits can be submitted to similar management strategies without impairing the forage canopy exploitation by the animals.

Highlights

Information on the structural components of the forage canopy is essential to establish pasture management strategies since during the occupation period in rotational stocking the animals tend to develop defoliation strategies that reduce the forage mass and canopy height (HODGSON, 1990).understanding the defoliation dynamics at the tiller level and the respective components of grasses, especially in tropical climates, can contribute to the establishment of management goals (LEMAIRE et al, 2009; MAZZANTI; LEMAIRE, 1994).climate fluctuations during the year and grasses with different structures can cause variations in the morphological components, which in turn alter the patterns of pasture exploitation, influencing the removal of herbage (CARVALHO, 2013)
These observations lead to the following hypothesis: structural variations in Brachiaria brizantha pastures (EUCLIDES et al, 2008; LARA; PEDREIRA, 2011) can modify the grass defoliation dynamics during the year
The objective of this study was to assess the defoliation dynamics during the occupation of pastures formed of three Brachiaria brizantha cultivars under rotational stocking during the year

Summary

Introduction

Information on the structural components of the forage canopy is essential to establish pasture management strategies since during the occupation period in rotational stocking the animals tend to develop defoliation strategies that reduce the forage mass and canopy height (HODGSON, 1990). Climate fluctuations during the year and grasses with different structures can cause variations in the morphological components, which in turn alter the patterns of pasture exploitation, influencing the removal of herbage (CARVALHO, 2013). These observations lead to the following hypothesis: structural variations in Brachiaria brizantha pastures (EUCLIDES et al, 2008; LARA; PEDREIRA, 2011) can modify the grass defoliation dynamics during the year.

Objectives

Methods

Results