111 Pathogenic Bacterial Levels in US Silages. (30th November 2020)

• Record Type: Journal Article
• Authors: Rehberger, Tom; Thompson, Jesse
• Is Part Of: Journal of animal science. Volume 98(2020)Supplement 3
• Page Start: 20
• Page End: 21
• Publication Date: 2020-11-30
• Subjects: silage -- clostridia -- E. coli; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skaa054.035
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: Fresh forage crops have traditionally been preserved by fermentation, either based on the spontaneous fermentation by epiphytic lactic acid bacterial populations or driven by the addition of lactic acid bacteria inoculant cultures. Although this method of preservation is effective at retarding the spoilage and pathogenic bacteria it does not eliminate these organisms from the forage. Spore-forming and other bacteria are often able to survive the low pH and organic acid levels in the fermented forages and outgrow during feed-out and in the animal. The purpose of this research was to understand the levels and diversity of pathogens in silage systems as an important prerequisite to develop effective ways to control them. From February 2016 to December of 2019, 866 corn silage samples and 577 haylage samples were collected from 457 US dairy farms across 27 states to assess the pathogenic levels in silage. Results indicate the clostridia levels in the haylage samples averaged 9.4 x 103 cfu/g with a range of less than 10 cfu/g to 4.1 x 106 cfu/g. Corn silage had a significantly lower level of clostridia (p<0.05) averaging 2.3 x 103 cfu/g. Clostridium perfringens was the dominant species identified in both haylage and corn silage and accounted for more than 60% of all the clostridia isolates. The other major clostridia species identified were C. beijerinckii, Paraclostridium bifermentens and C. butyricum. E. coli levels were also determined in the haylage and corn silage samples. In haylage, the average E. coli level was 2.1 x 104 cfu/g and ranged from less than 10 cfu/g to 2.5 x 106 cfu/g and were significantly higher (p<0.05) than levels detected in corn silage (average of 5.4 x 101 cfu/g). Further work is underway to determine the source of these pathogens and methods of controlling through the fermentation process.