Variations in bacterial communities in laboratory-scale and big bale silos assessed by fermentation products, colony counts and denaturing gradient gel electrophoresis profiles

Abstract

To assess the variation in bacterial communities in laboratory-scale and big bale silos. Wilted Italian ryegrass (628 g dry matter kg(-1)) was ensiled in vacuum-packed plastic pouches and big bales. Silos were opened after 3 months, and the fermentation products, colony counts and denaturing gradient gel electrophoresis (DGGE) profiles were determined. Eight samples were collected separately from a big bale, while one representative sample was taken from a plastic pouch. Significant variation was found between big bales in dry matter, ethanol, lactic acid, acetic acid and ammonia-N contents. No differences were shown between plastic pouches and big bales, except that more ethanol was produced in the former air-tight silos. Plastic pouches could resemble a specific silo and outer sampling sites of big bales based on fermentation products and DGGE profiles respectively. Considerable variation in fermentation products may exist between big bale silos. Plastic pouches can serve as a model of big bale silos, although they do not provide information on the heterogeneity within and between bales. Assessment of bacterial communities associated with ensiling can differ according to the criteria of fermentation products, colony counts and DGGE profiles.