Physicochemical properties, fermentative profile, microbiological quality, and pathogen contamination of baled silage during long‐term storage

Abstract BACKGROUND Baled silage is expanding in Mediterranean regions due to climate change and demand for high‐quality forage; therefore, evaluating the effects of long‐term storage on microbiological and fermentative quality is essential. RESULTS In this study, 115 baled silages were sampled from different farms at 30, 60, 90, 180, and 270 days after baling. Chemical composition, fermentative compounds, microbial groups, and the presence of pathogens were assessed. The ensiling period did not affect any chemical parameter measured. Low concentrations of ammonia nitrogen (33.56 ± 27.33 g kg −1 total Kjeldahl nitrogen) were observed, and butyric acid was detected in only five samples, with a mean concentration of 2.11 ± 0.46 g kg −1 . Lactic and acetic acids averaged 35 ± 1.99 and 15 ± 1.05 g kg −1 dry matter, respectively, with lactic acid decreasing and acetic acid increasing over time. Lactic acid bacteria were found at optimal concentrations (5.42 ± 2.50 log 10 CFU g −1 ), contributing an average pH of 4.28 ± 0.48. Clostridia were absent in 73% of samples, and when detected ranged from 1.69 to 3.46 log 10 CFU g −1 . Fungi were found in 22% of samples (ranging from 2 to 6.19 log 10 CFU g −1 ). Neither Escherichia coli nor Listeria monocytogenes was detected, indicating correct application of silage production techniques. CONCLUSION After 270 days of storage, baled silage preserved its chemical–physical and microbial quality under Mediterranean farming conditions. pH remained stable, while lactic acid declined and acetate/1,2‐propanediol increased over time. Fungi and clostridia were mostly undetectable; E. coli and L. monocytogenes were not detected. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.