Abstract: The effect of corn silage substituted for hay as forage source on low producing dairy cow performance and composition of milk was investigated. A total number of 12 half-bred Holstein cows averaging 10 kg/d of milk, allocating 6 cows in each group were used in the study. The ration containing hay formed hay group and the ration containing corn silage formed silage group. Dry matter intake and milk production were insignificantly higher (p>0.05) in silage group when compared with hay group. As chemical composition of the milk in groups observed, dry matter, ash, fat and protein decreased insignificantly (p>0.05) in silage group.