: Wilted grass and whole-crop maize silages taken from farm silos in northern Germany were analysed for fermentation pattern, mould counts and composition of mycoÑora as well as for roquefortine C. In general, increasing DM contents of visibly unmoulded silages resulted in decreasing amounts of volatile fatty acids and a greater portion of samples with a high number of mould propagules. The average mould count of these silages was found to be 1É4 ] 104 cfu g~1, whereas visibly moulded samples contained about 1 ] 108 cfu g~1. Penicillium roqueforti was the predominating fungal species in silages occasionally accompanied by species of the genera Aspergillus, Mucor, Monascus and/or Geotrichum. Penicillium roqueforti was detected in 89% of the visibly moulded and in 85% of the visibly unmoulded samples. Of 24 visibly moulded silages tested, 21 samples contained roquefortine C, a mycotoxin known to be produced by P roqueforti. The highest level of roquefortine C found was 36 mg kg~1 DM. Even 6 of 24 visibly unmoulded samples analysed for this mycotoxin were contaminated with roquefortine C but only in trace amounts. Roquefortine C is considered as a model compound for the biosynthesis of toxic fungal metabolites produced by P roqueforti in silages. The P roqueforti-count can be employed as a criterion to predict the contamination of silages with mycotoxins produced by this fungal species.1998 SCI. ( J Sci Food Agric 76, 565È572 (1998)

Ensiling conditions strongly influence fermentation characteristics, yeast count, and aerobic stability. Numerous volatile organic compounds including esters are produced, which may negatively affect feed intake and animal performance and air quality. In addition to a farm survey, 3 laboratory experiments were carried out to study the effects of air (by delayed sealing or by air infiltration during anaerobic storage), temperature (20 and 35°C), and various types of additives [blends of either sodium benzoate and sodium propionate (SBSP) or of sodium benzoate and potassium sorbate (SBPS); buffered mixture of formic and propionic acids (FAPA); homofermentative inoculant (LAB)]. After additive treatment, chopped whole corn plants were packed into 1.5-L glass jars and stored for several months. For treatments with air infiltration, glass jars with holes in the lid and body were used. The farm survey in 2009 revealed large variation in lactate, acetate, ethanol, n-propanol, and 1,2-propanediol concentrations. Whereas ethyl esters were detected in all silages, the mean ethyl lactate concentrations were higher than those for ethyl acetate (474 vs. 38mg/kg of dry matter). In the ensiling experiments, few unequivocal effects of the tested factors on the analyzed parameters were observed due to many interactions. Delayed ensiling without additives decreased lactic acid production but, in one trial, increased acetic acid and had no effect on ethanol. The effect of delayed sealing on yeast counts and aerobic stability differed widely among experiments. Air infiltration during fermentation tested in one trial did not alter lactic acid production, but resulted in more acetic acid in delayed and more ethanol than in promptly sealed untreated silages. Greater ethanol production was associated with increased yeast numbers. Storage at high temperature resulted in lower lactic acid and n-propanol, and a trend toward reduced ethanol production was observed. The additive FAPA consistently caused increased ethanol and reduced n-propanol levels with no effect on yeast counts and aerobic stability. When the additives SBSP and SBPS decreased n-propanol and ethanol, reduced yeast counts were also found. Ethyl ester formation was strongly correlated with those of ethanol and to a lesser degree with those of the respective acid.

As farm profitability and sustainability of animal production are largely affected by overall losses of dry matter and nutritive value of silage from field to trough, the objective of the study was to assess the effects of different additive types on fermentation, aerobic stability (ASTA) and changes in in vitro organic matter digestibility (IVOMD) and metabolisable energy (ME) of grass and grass–clover silage exposed to air. Three trials were performed, where grass and grass–clover forages were treated with biological and chemical additives and ensiled in 1.6-L glass jars. Upon silo opening, fermentation characteristics, yeast counts and ASTA were determined as well as changes in IVOMD and ME during subsequent air exposure for up to 336 h. All silages were well preserved. The ASTA was improved by Lactobacillus buchneri-containing additives in all trials and by chemical additives in trial 3. In untreated silage, aeration reduced IVOMD and ME but variable effects of additives were observed. The nutritive value was maintained throughout aeration by all additives in trial 1, whereas in trial 3, only chemical additives were successful. A strong negative linear relationship across trials was detected between the extent of aerobic deterioration and changes in ME during air exposure (r = −0.756, p < 0.001). Silage additives improving aerobic stability have the potential to prevent the loss of nutritive value of grass and grass–clover silage during feed-out.

Wilted grass and whole‐crop maize silages taken from farm silos in northern Germany were analysed for fermentation pattern, mould counts and composition of mycoflora as well as for roquefortine C. In general, increasing DM contents of visibly unmoulded silages resulted in decreasing amounts of volatile fatty acids and a greater portion of samples with a high number of mould propagules. The average mould count of these silages was found to be 1·4×104 cfu g−1, whereas visibly moulded samples contained about 1×108 cfu g−1. Penicillium roqueforti was the predominating fungal species in silages occasionally accompanied by species of the genera Aspergillus, Mucor, Monascus and/or Geotrichum. Penicillium roqueforti was detected in 89% of the visibly moulded and in 85% of the visibly unmoulded samples. Of 24 visibly moulded silages tested, 21 samples contained roquefortine C, a mycotoxin known to be produced by P roqueforti. The highest level of roquefortine C found was 36 mg kg−1 DM. Even 6 of 24 visibly unmoulded samples analysed for this mycotoxin were contaminated with roquefortine C but only in trace amounts. Roquefortine C is considered as a model compound for the biosynthesis of toxic fungal metabolites produced by P roqueforti in silages. The P roqueforti‐count can be employed as a criterion to predict the contamination of silages with mycotoxins produced by this fungal species. © 1998 SCI.

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium moniliforme and F. proliferatum. Little is known of its metabolic fate after oral ingestion in ruminants, but these animals are reported to be tolerant towards FB1. The metabolism of this mycotoxin was evaluated following incubation (1 microg/ml) in ruminal fluid for up to 72 h, in the presence or absence of alfalfa as a substrate for microbial growth, using a model rumen (sealed flask, anaerobic conditions, exclusion of light, gentle agitation, 39 degrees C). The decrease in FB1 concentration and the production of short-chain fatty acids were determined. FB1 had no effect on SCFA production. After 72 h incubation, FB1 depletion was 12% and 18% in samples with and without alfalfa, respectively. No hydrolysed metabolites (aminopolyols or aminopentol) were detected. These results indicate that FB1 is poorly metabolized in the rumen and suggest that such metabolism is not the cause of the tolerance to this toxin displayed by ruminants.