Sward structural characteristics and herbage accumulation of Panicum maximum cv. Mombaça subjected to rotational stocking managements

Sila Carneiro da Silva,Jozivaldo Prudêncio Gomes de Morais,Adriana Amaral de Oliveira Bueno,Cory Matthew,Fernando Oliveira Bueno,John Hodgson,Greg C. Arnold,Roberta Aparecida Carnevalli,Marina Castro Uebele

doi:10.1590/s0103-90162009000100002

Sila Carneiro da Silva, Jozivaldo Prudêncio Gomes de Morais + Show 7 more

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https://doi.org/10.1590/s0103-90162009000100002

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Abstract

Grazing strategies promote changes in sward structure that can affect patterns of herbage accumulation and sward flexibility to management. This experiment evaluated sward structural characteristics and herbage accumulation of Mombaça guinea grass (Panicum maximum Jacq. cv. Mombaça) subjected to rotational stocking managements. Treatments involved grazing when swards reached either 95 or 100% interception of the incident light (LI), to post-grazing heights of 30 and 50 cm, and were allocated to 2,000 m² paddocks according to a randomised complete block design in a 2 × 2 factorial arrangement with four replications, from January 2001 to February 2002. Sward canopy changed from a vertical to a more horizontal orientation as the light interception area index and height increased from post to pre-grazing. Leaf canopy height pre-grazing was stable throughout the year and around 90 and 115 cm for the 95% and 100% LI treatments respectively, indicating a potential for development and use of target-based grazing management practices. Herbage mass pre and post-grazing was lower for the 95% than the 100% LI treatments, but with higher proportion of leaf and lower proportions of stem and dead material. Treatment effects on herbage accumulation were cumulative and became more evident as the experiment progressed, with up to 6 t ha-1 DM advantage to the 95/30 treatment. Although based on a single year experiment, grazing management should aim for low herbage mass during the transition period from winter to spring in order to allow fast recovery of swards and favour herbage accumulation during the following growing season.

Highlights

MATERIAL AND METHODSDuring the last 35 years there have been significant changes in grassland farming in Brazil
Sward canopy changed from a vertical to a more horizontal orientation as the light interception area index and height increased from post to pre-grazing
Leaf canopy height pre-grazing was lower for the 95% than the 100% LI treatments (88.7 vs 115.4 cm, s.e.d. = 2.09) and values were relatively constant for the 95% but increased for the 100% LI treatments throughout the year (109.8 to 124.3 cm from summer 1 to early summer 2, respectively; Figure 3)

Summary

Introduction

MATERIAL AND METHODSDuring the last 35 years there have been significant changes in grassland farming in Brazil. Recent studies have demonstrated that principles of grazing management and animal production from tropical pastures need to be reappraised (Da Silva & Carvalho, 2005), and that understanding of functional responses of plants and animals to variations in sward state is essential (Hodgson, 1985) This approach has been adopted in the past for temperate forage species and resulted in significant progress towards the understanding of plant and animal responses to manipulation of sward conditions. In this context, variables like stocking rate, herbage allowance and defoliation interval are considered as means of achieving sward control and not as ends in themselves (Hodgson & Da Silva, 2002). This represents a major conceptual change in the traditional approach towards research and management that was not applied to tropical pastures in Brazil until the late 1990’s (e.g. Gomide, 1997)

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