Chemical and microbiological changes and aerobic stability of marandu grass silages after silo opening

Thiago Fernandes Bernardes,Rafael Camargo Do Amaral,Ricardo Andrade Reis

doi:10.1590/s1516-35982009000100001

Thiago Fernandes Bernardes, Rafael Camargo Do Amaral + Show 1 more

Open Access

https://doi.org/10.1590/s1516-35982009000100001

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Abstract

This trial had the objective of characterizing the microbial population and evaluating the aerobic stability of Marandu grass silages with pelleted citrus pulp (PCP). The collected forage was submitted to the following treatments: Silage of Marandu grass; silage of Marandu grass + 50 g/kg PCP and silage of Marandu grass + 100 g/kg PCP on natural matter basis. Metal cylindrical containers with 80 cm of height and 50 cm of diameter were used as silos during assays of microbiological dynamics and chemical changes of silages in anaerobiosis. Evaluations were performed on days 0, 2, 4 and 6 after silos were opened. The aerobic stability was evaluated by change in temperature, using approximately three kilograms of silage inside styrofoam boxes that were placed inside a climatic chamber. A completely randomized experimental design and split plot arrangement were used in the two assays, with five replications. Treatments were the plots and time was the subplots. Bacillus and enterobacteria were present on the Marandu grass silages with 0 g/kg PCP, which also showed pH increase throughout the feedout phase. Yeast was detected on the silages that were added with PCP. A trend of increasing temperature with extension of the aeration time was observed mainly in the silages containing 100 g/kg PCP. Isolated yeast strains showed lactate assimilation. Silages were found to be unstable due to the silo opening, both by bacterial or yeast development, which reduced the nutritional value.

Highlights

The anaerobic environment of a silo responsible for forage conservation becomes aerobic when the silo is opened
Bacillus and enterobacteria were present on the Marandu grass silages with 0 g/kg pelleted citrus pulp (PCP), which showed pH increase throughout the feedout phase
Enterobacteria were detected in the silage containing 0 g/kg PCP and increased after silo opening (P

Summary

Introduction

The anaerobic environment of a silo responsible for forage conservation becomes aerobic when the silo is opened. In such conditions, organisms that are latent in the absence of oxygen multiply rapidly, and silage is degraded. Some well-fermented silages with additives and presenting high lactic acid levels and remaining sugars seem to be subject to fast deterioration by these microorganisms. The reason for such instability in silage supplemented with additives is probably related to the greater contents of energy sources for microorganisms involved in aerobic degradation (Kung et al, 2003)

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