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Doctoral thesis, 2019

Filamentous fungi in wrapped forages

Schenck, Jessica

Abstract

Wrapped forages of higher dry matter (DM) concentrations (> 50 %), also referred to as haylage are common in Sweden and Norway. Such forages are preserved by a combination of semi-drying and anaerobic storage leading to an environment that may affect the composition of filamentous fungi differently than in hay or silage. The aim of this research was to identify fungal species in wrapped forages with higher DM concentration in relation to forage production and management factors.

In the first study, the effect of plant maturity at harvest on microbial composition of forage was investigated. The microbial composition of fresh herbage and conserved haylage was compared for three different harvest times (June, July and August) of the first cut of the season. The fungal load increased with later harvest dates in haylage, but fungal species detected in the herbage were not detected in the haylage. In the second study, bales from 124 farms were sampled, and data on production factors, chemical composition and mycotoxin presence included. Samples for analysis of fungi were taken from patches with visible fungal growth on the bale surfaces, and from drilled samples from the forage. Results showed a higher risk of fungal presence with increasing DM concentration, or if less than eight layers of polyethylene stretch film were used for wrapping. Presence of mycotoxins and their respective fungal species were not correlated (P>0.05). However, higher fungal counts were positively correlated with presence of mycotoxins.

Ocular inspection and cultivation for identification of fungal species is timeand labour consuming and has inherent difficulties. Therefore, identification of fungal species by extracting fungal DNA directly from forage samples is of interest. A study on three new primers in the fungal ITS (internal transcribed spacer) region for 454-sequencing was performed. Results showed that not all fungal species can be identified in the ITS-region and therefore other DNA regions are of interest.

Keywords

filamentous fungi; mould; wrapped forages; haylage and mycotoxins

Published in

Acta Universitatis Agriculturae Sueciae
2019, number: 2019:69
ISBN: 978-91-7760-456-3, eISBN: 978-91-7760-457-0
Publisher: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences