Effect of organic acids on numbers of yeasts and mould fungi and aerobic stability in the silage of corn.

The aim of these studies was to assess the effect of chemical conservants (FA = formic acid, PA = propionic acid, FPA+i = formic acid, propionic acid and ammonium ions) on the cell counts of yeasts and mould fungi in silage. The silage was prepared from corn (Zea mays L), cultivar Buran FAO (240). The effect of the applied conservants on silage aerobic stability was also assessed. The performed chemical analyses comprised the determination of: the content of dry matter (DM), lactic acid (LA), acetic acid (AA), ethanol, water soluble sugars (WSC), crude protein (CP) and pH. The applied preparations were found to reduce the number of yeast and mould fungi cells in all the examined silages. The growth of fungi was inhibited most strongly by the FPA+i preparation (containing a mixture of formic and propionic acids and ammonium ions). The yeast cell counts dropped (P<<0.05) from 8.50 107 CFU g(-1) silage in the control (CCS = control corn silage) to 2.60 107 CFU g(-1) in silage treated with FPA+i, whereas counts of the mould fungi cells - from 15.20 104 CFU g(-1) silage in the control to 4.60 104 CFU g(-1) in silage treated with FPA+i. The applied conservants increased (P<<0.05) the content of DM from 255.00 g kg(-1) in control to 266.60 g kg(-1) with PA, WSC from 27.10 g kg(-1) DM to 30.50 g kg(-1) DM with FPA+i and ethanol from 9.10 g kg(-1) DM to 11.21 g kg(-1) DM with FPA+i in the silage. The additives decreased concentrations of lactic acid, acetic acid and crude protein concentration after opening the barrels. The diversifying factors decreased the pH value in the examined silage. The experimental conservants were found to improve the aerobic stability of silages after 7 days of air exposure.