Additives and inoculants are the focus of silage research, as new additives and their combinations can improve fermentation and silage quality. We performed two trials evaluating two doses (4 and 8 g/t, wet weight) of natamycin as an additive to maize silage compared to a control without supplementation. In the first trial, we assessed fermentation losses, yeast count, chemical composition, and aerobic stability of maize silages stored in pilot-scale silos using four replicates per treatment. The second trial was designed to evaluate the voluntary intake and performance of lambs fed the treated silages prepared in bunker silos. The lambs (10 lambs/treatment) were kept in individual pens and fed twice daily a total-mixed ration containing one of the treated silages. The highest dose of natamycin decreased dry matter and gas losses. The yeast count in the silages from the bunker silos tended to increase (r = 0.92) over the weeks. There was no significant difference in voluntary feed intake or average daily gain of lambs fed natamycin silages compared to the control silage. Since high natamycin doses caused a decrease in fermentation losses in maize silage and exerted no deleterious effects on animal performance, this bacteriocin may soon be considered a potential component of silage additives.