Le concentrazioni degli acidi organici quali indicatori per la valutazione qualitativa degli insilati di mais

Thirty nine corn silage samples, produced in 2007 in Teramo Province (Italy) were analysed for chemical composition, fibre fractions, soluble protein (Cornell), pH and organic acids content (citric, D-(+)-malic, trans-aconitic, D,L-lactic, acetic, fumaric, propionic, and n- butyric. None sample showed detectable amount of citric, fumaric and n-butyric acids while only 26% of samples showed detectable amount of propionic, 62% of D-(+)-malic acid and 82% of trans-aconitic. pH do not seems to be an helpful parameter to evaluate fermentation characteristics of corn silage indeed the greater correlation regarding pH were thats with NDF (r=0.576; P<0,001) and soluble protein (r=0.565; P<0,001) due probably to their buffer capacity. Dry matter (DM) of corn silage was strongly and negatively related to crude protein (-0,718; P<0,001), total organic acids content (TOAC; r=-0,826; P<0,001) and NDF (r=-0,61; P<0,001). Furthermore acetic acid was more related to TOAC than lactic acid (r=-0,827 vs r=-0,656; P<0,001) indeed total organic acids content was negatively related to lactic/acetic ratio (r=-0,619; P<0,01). Data of this paper suggest that wet corn silages is often better preserved than others because more rich in organic acids.