Two experiments were conducted at La Platina Experiment Station (INIA), Santiago, Chile, in order to quantify the losses of grains in faeces of lactating cows fed a diet based on maize silage, harvested at the milk or dough-hard stages of maturity. In addition, the cows were fed alfalfa hay and concentrate according to milk yield. The excretion of grains in faeces was scarce with both types of silages. Total daily losses were higher with the dough-hard grain silage. As a proportion of the total consumption of grains, losses were higher (P< 0.05) with the milk stage grain silage (2.27%, average of both experiments), in relation to the more mature silage (0.92%). The content of neutral-detergent fiber and starch in grains from silages and faeces were very similar. As a result of the markedly higher intake of grains with the more mature silage and the similarity in faecalgrain losses with both silages, the amount of grains digested and absorbed were considerably higher when the dough-hard grain stage silage was fed.