Grazing Intensity Impacts on Herbage Mass, Sward Structure, Greenhouse Gas Emissions, and Animal Performance: Analysis of Brachiaria Pastureland

Ana Cláudia Ruggieri,Mariane Vieira Azenha,Liziane De Figueiredo Brito,Ricardo Andrade Reis,Rondineli Pavezzi Barbero,Abmael Da Silva Cardoso,Fernando Ongaratto,Daniel Rume Casagrande,André Alves Oliveira,Jefferson Fabiano Werner Koscheck

doi:10.3390/agronomy10111750

Abstract

A 7 year experiment (2008–2014) evaluated cattle grazing intensity (sward height) effects on herbage mass, forage quality, and greenhouse gas emissions in continuously stocked pastures containing the tropical ‘Marandu’ palisade grass (Brachiaria brizantha (Hochst. ex A. Rich) Stapf cv. Marandu). The experiment consisted of three sward height treatments (15, 25, and 35 cm) and six replicates. There were four periods each year during the rearing phase. Significant effects were found for herbage mass, proportions of leaf and stem, crude protein, neutral detergent fiber, acid detergent fiber, lignin, animal performance, enteric methane (CH4), and greenhouse gas (GHG) emissions from soils. When the canopy height increased from 15 to 35 cm, the herbage mass rose from 5.23 to 9.86 kg t ha−1, leaf percentage decreased, and stem percentage increased. Crude protein content averaged 14.2%, and neutral detergent fiber averaged 58%. Average daily gain averaged 0.67, 0.81, and 0.90 kg −1 head−1, while live weight gain ha–1 was 649, 530, and 439 kg for the 15, 25, and 35 cm treatments, respectively. The weather variables explained the GHG emissions, interannual herbage mass, and structure variations.

Highlights

Beef cattle production is an important source of protein, minerals, and vitamins for human nutrition
The data from this study showed that in the first and third years, the results were in line with previous studies because they showed that neutral detergent fiber (NDF) content and enteric CH4 production were greater in the 35 cm pasture treatment than in the other treatments (Table 6)
The principal component analysis revealed that weather-related variables had a strong effect on the structure and nutritive value of the sward

Summary

Introduction

Beef cattle production is an important source of protein, minerals, and vitamins for human nutrition. It requires significant quantities of natural resources and may negatively impact the environment through greenhouse gas (GHG) emissions [1,2,3]. Agronomy 2020, 10, 1750 in tropical regions, but tropical grasses usually have low crude protein (CP), and high neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations, which lead to lower animal performance and greater enteric methane (CH4 ) emissions [2,4]. Reasons for the success of Brachiaria are the adaptation and persistence of these grasses in soils with low pH associated aluminum toxicity, phosphorus (P) deficiency, and low soil organic matter [6]. This study investigated the Marandu palisade grass cultivar in a long-term study

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Discussion

Conclusion