Pioneiro grass (Pennisetum purpureum) has gained importance in silage production mainly due to its robust habit, perenniality and high yield capacity, although its typically high moisture content may reduce its potential for conservation as silage. High moisture content at the time of ensilage has resulted in increased losses as gases and effluents (Balsalobre et al. 2001; Nussio 2005). Despite these losses, the high yields of tropical forages still justify their use and study as roughage and silage in ruminant nutrition. However, maize silage is still used widely across different systems because of its favorable natural characteristics for fermentation, resulting in production of high quality silage (Anaya-Ortega et al. 2009). An experiment was conducted to evaluate the individual and combined effects of maize and Pioneiro grass on the total losses from the silages during the ensiling process.