The aim was to evaluate the fermentative dynamics and nutritional characteristics of mixed maize silages with and without commercially viable cobs associated with butterfly pea hay. A completely randomized experimental design was used in a 2 × 2 factorial scheme, with 4 replications, which corresponded to the maize cobs factor and the butterfly pea hay factor (inclusion of 30% of butterfly pea hay during the ensiling process and without the inclusion of butterfly pea hay). The inclusion of butterfly pea hay increased the dry matter contents, reduced the silage density and its interaction with the absence of viable cobs promoted less losses and greater dry matter recovery (P < 0.05). The lowest value of butyric acid was found in the interaction of silage without viable cobs and butterfly pea hay (P < 0.05). The inclusion of butterfly pea hay reduced fiber contents and increased protein contents (P < 0.05). The inclusion of 30% butterfly pea hay promotes better values of organic acids, nutritional components and lower fermentation losses when the maize is ensiled without cobs that are viable for commerce.