The aim of this study was to compare the chemical composition, fermentation quality, and in vitro ruminal fermentation characteristics of several silages from different maize genotypes. For this purpose, maize plants of six genotypes (G1–G6) were grown in the same field, harvested at the same time, and then ensiled in laboratory silage bags. Significant differences (P < 0.05) were observed among silages in dry matter, neutral detergent fibre, non-fibre carbohydrates, pectin + sugars, crude protein, ash, and ether extract contents (P < 0.05). Pectin + sugar contents varied between 12.70 and 22.44% (P < 0.05). Lactic and acetic acid concentrations also differed among genotypes (P < 0.05). In vitro ruminal fermentation values, including total gas production after 24 h, metabolizable energy, organic matter digestibility, net energy for lactation and concentrations of acetic, propionic and butyric acids differed significantly between silages (P < 0.05). Crude protein content was positively correlated with haemicellulose (P < 0.05), while acid detergent fibre and cellulose contents were negatively correlated with pectin, sugars and lactic acid. Pectin and sugar content was positively correlated with gas production after 24 h and lactic acid levels. These findings indicate that differences in carbohydrate fractions between maize genotypes may influence silage quality and in vitro ruminal fermentation characteristics, and consequently affect energy values and digestive responses in ruminants.