The preservation of feedstuff for animal consumption (forages) by fermentation or dehydration is a common practice to supplement pastures and achieve better yields. Currently, the quality of a forage has been evaluated only through chemico-fermentative parameters. However, animals' health can also be affected by the presence of bacteria, molds, and/or some of their metabolites, e.g. mycotoxins. The quality of 147 forage samples (55 sorghum, 49 lucerne, and 43 maize) used for feeding dairy cattle, was evaluated using chemicofermentative (pH, ammonial nitrogen/total nitrogen ratio) characteristics, fungal propagule counts, and the presence of Aspergillus fumigatus and mycotoxins (aflatoxins and deoxynivalenol). Most lucerne samples (55.1%) were of bad chemico-fermentative quality (risky for consumption). In addition, a high percentage of samples (38.8% lucerne, 65.1% maize and 69.1% sorghum) presented Fairly Good (doubtful) chemico-fermentative characteristics. Maize samples showed the highest frequency of contaminated samples by high counts (25.6%), followed by lucerne (with a lower fermentative sugar content) (18.4%), and sorghum (16.4%). The mycoflora was distributed in 59 species belonging to 26 genera. In all forages, molds were the most numerous isolates, with the greatest number of isolates being Aspergillus species (17% isolates) with numerous isolates in the section Flavi, followed by Penicillium (9.7%) in maize, Fusarium (12.3%) in lucerne, and Byssochlamys (8.5%), Fusarium and Geotrichum (6.1% each) in sorghum. Even though the lucerne and maize samples presented a high mycotoxin incidence, and in most of them the simultaneous presence of AF and DON was detected, average values were not very high (AF: 6.78 and 6.96 mu g/kg, DON: 1666.67 and 717.50 mu g/kg, respectively for lucerne and maize). The high degree of contamination registered in the samples (81.6% lucerne, 67.4% maize and 45.5% sorghum) indicates the need for improving the technology applied during the development of crops, their harvest and the preparation and conservation of forages. It could be determined (p < 0.05) that AF + DON are contamination markers in lucerne and maize silages. In sorghum forages, a significant association (p < 0.01) was detected between risk and storage method. (C) 2006 Elsevier B.V. All rights reserved.
