The prevalence of mycotoxins and their relation to nutrient composition of maize and grass silage

Abstract

In this study, samples of maize and grass silage were collected from various farms of Lithuania and were analysed for mycotoxins: aflatoxin B 1 (AFB 1 ), deoxynivalenol (DON), T-2 toxin (T-2) and zearalenone (ZEA), over the 2017-2019 period. Silage nutrient composition, including content of dry matter, crude protein, crude fibre, starch (for maize), and acidity (pH) were investigated, and fermentation degree was computed. All samples contained at least one mycotoxin, 85% of samples were co-contaminated with all four mycotoxins tested, 13% of samples contained three and only 1.5% of samples contained two mycotoxins. In general, the concentrations of DON, ZEA and T-2 were respectively 5, 1.7 and 2 times higher in maize silage than in grass one. Maize silage had the highest levels of ZEA and AFB 1 , exceeding the European Union's (EU) maximum allowable limits. In grass silage, mycotoxin with the highest concentration exceeding the allowable limits was AFB 1 . Between the experimental years, statistically significant differences were found only in T-2 content in maize silage. Silage storage had an impact only on AFB 1 concentrations: its highest concentration (10.9 ± 1.1 μg kg -1 ) was found in trench silos, while in silage clamps and bales that ones were lower by 48% and 44%, respectively. DON negatively correlated with dry matter in grass silage. ZEA negatively correlated with crude protein content and pH in maize silage and with dry matter and crude fibre content and pH in grass silage, but positively correlated with fermentation degree in both silages. T-2 negatively correlated with crude protein content and positively correlated with crude fibre content in grass silage.

Does Digestate Dose Affect Fodder Security and Nutritive Value?

“…Mycotoxin contamination is highly dependent on weather conditions and, therefore, can change both during the vegetation season and throughout the year [16,48,49]. This was partially the case in our study, where significant differences in DON, AFB1, and T-2 were observed between 2019 and 2020, as shown in Table 4 (p < 0.05).…”

“…In our study, there were no increased levels of DON, AFB1, or T-2 in the biomass when compared to the unfertilized control, which suggests that there was no increased contamination by fungal producers of these mycotoxins. Venslovas et al came to similar conclusions in grass silage [49]. Therefore, the risks of such contamination are not increased using digestate on permanent grasslands, but more research is needed on other agricultural crops.…”

Epiphytic microflora and mycotoxin content in meadows–Is plant biodiversity affecting fungal contamination?

“…Zachariasova et al [ 21 ], however, state that maize leaves and corncobs contain higher amounts of protein and polysaccharides than grass, therefore they provide suitable conditions for surviving and spreading of fungi and other microorganisms. Moreover, in the study of Venslovas et al [ 38 ], negative correlation between crude protein and crude fiber levels as well as ZEN concentration in silage samples was found. Higher percentage of protein-rich components occur in legumes species.…”

“…Presence of mycotoxins in key fodder crops such as maize as well as in small grain cereals and legumes e.g. pea and soy is well known [ 21 , 37 , 38 ]. Infection by toxicogenic fungi depends on many abiotic factors, such as weather conditions, nutrient deficiency or excess, and biotic factors, such as insect damage.…”

“…Similarly to our experiment, Schenck et al [40] did not find any correlation between organic nutrients and OF counts or mycotoxin concentrations. On the PLOS ONE other hand, Venslovas et al [38] found that DON concentration was negatively correlated with dry matter content of grass silage.…”