Distribution of moulds and mycotoxins in maize grain silage in the trench silo

V Krnjaja,C Radovic,Lj Stojanovic,S Stankovic,T Petrovic,M Gogic,J Levic

doi:10.2298/bah1204845k

Abstract

In this study the mycological and mycotoxicological contamination of maize silage samples collected from the bottom (BL), middle (ML) and top (TL) layer in the silage trench silo was studied. Mycological testing of the silage contamination showed the presence of five potential toxigenic fungi of the genera, Aspergillus, Fusarium, Mucor, Penicillium and Rhizopus with their total number ranging from 1 to 10 x 103 CFU g-1. Also, four mycotoxins were detected as followed, aflatoxin B1 (AFB1), zearalenone (ZON), deoxynivalenol (DON) and fumonisin B1 (FB1). Mycotoxins AFB1 and FB1 were detected as 100% positive in all the samples tested. An average concentration of AFB1 was 2.31 ?g kg-1, 2.51 ?g kg-1 and 2.81 ?g kg-1 in BL, ML and TL respectively, while the concentration of FB1 was 1292.00 ?g kg-1, 1298.00 ?g kg-1 and 1902.00 ?g kg-1 in BL, TL and ML respectively. Average concentration of toxin ZON in positive samples was 15.69 ?g kg-1 in BL and 30.68 ?g kg-1 in ML, while its presence in the samples taken from the top layer was not detected. An average concentration of DON toxin in positive samples were in the range of 41.71 ?g kg-1 for TL, 79.20 ?g kg-1 for ML, while it was 97.00 ?g kg-1 for BL. There was no statistically significant correlation between moisture content and total number of moulds and concentrations of certain mycotoxins. However, statistically highly significant correlations between the total number of moulds and AFB1 concentration (r = 1.0), ZON (r = 0.99) and FB1 (r = 0.91) were established, while weak correlation was obtained in the case of DON and total mould counts (r = 0.54).

Highlights

After rice and wheat, maize is consider as an important crop in the World, (Reddy and Salleh, 2011), and the most important component of animal feed
According to mycological analysis of tested samples the total number of moulds per gram was in the range of 4-7 x 103, 2-10 x 103 and 1-5 x 103 for the samples in the bottom layer (BL), middle layer (ML) and top layer of the trench silo (TL), respectively (Table 1)
In mycological studies of 18 samples of feed mixture intended for fattening swine which were collected from three different provinces of Serbia, Milićević et al (2010) have performed the total fungal counts of 105 to 40 x 105 and most frequently isolated were species of genus Penicillium (94.4%) followed by species of genera Fusarium (55.5%) and Paecilomyces (44.4%)

Summary

Introduction

Maize is consider as an important crop in the World, (Reddy and Salleh, 2011), and the most important component of animal feed. It has been used in human nutrition, and more recently as a raw material in energy production. The most common inoculants are Lactobacillus plantarum and other Lactobacillus spp. combined with Enterococcus, Lactococcus and Pediococcus species. These inoculants can increase the rate of acidification and reduce the final pH and protein degradation in silage (Driehuis et al, 1997). Poor conditions during ensiling, especially in mature silage during the 11 months, followed by exposure of silage to condensation, heating, leakage of rainwater, infection by insects can lead to proliferation of toxigenic fungi (moulds), biosynthesis of mycotoxins as well as reducuction of nutritional value of silage (Cleveland et al, 2003; Frisvad et al, 2006)

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