The experiment involved altogether 420 analyses of produced silage. In Group A, which consisted of samples of silage maize harvested in an optimum (or in a generally recommended) growing stage (when the so-called kernel milk line passed through the imaginary line of separation between the starchy tip and the milky base of individual grains in approximately two thirds of the grain), the results of 210 analyses ranged from 28 to 34 % of dry matter (DM) content. In Group B, the total number of analyses was also 210 and the crop was harvested in the maturity stage with a higher content of DM (34 to 40 %). A higher experimental (i.e. more than 34 %) vs. an optimum DM content (28 – 34%) showed a significantly negative effect on the chemical composition and quality of fermented of corn silage. The obtained results indicate that under practical conditions is can be recommended to harvest the crop in the growing stage characterised by the milk line passing through two thirds of kernels.