Abstract: A new midrib corn hybrid called Master Graze (MG) has been recently introduced in the US as a new forage source for cattle. However, before recommending its use to livestock producers, it’s important to evaluate its nutritional value. Therefore, the objective of this study was to evaluate the effects of using MG silage as a forage source in a lactating dairy cow’s diet on feed intake, milk yield, milk composition and nutrient digestibility. Sixteen Holstein cows, in mid lactation (120±19 DIM), were divided into four treatment groups (n = 4 cows/treatment) and fed treatment diets for 4 consecutive periods with each period consisted of 21 days. The cows on the control diet (CON) were fed a 60:40 forage:concentrate diet (dry matter (DM) basis) with corn silage and alfalfa hay as the forage source (1:1; DM basis). For treatment groups, the MG silage substituted the forage mix at 16% (MAS-16), 33% (MAS-33) and 50% (MAS-50) on a DM basis. All diets were formulated to be isonitrogenous. Cows were fed the treatment diets as a total mixed ration once daily. Substituting the corn silage-alfalfa hay mix with the MG silage at the three tested levels had no effects (p>0.05) on feed intake or milk production. Milk fat percentages and yields and milk protein percentages and yields were similar (p>0.05) among treatment diets. Relative to CON diet, the apparent digestibility of DM and OM were higher (p<0.05) in cows fed the MAS-50 diet and tended to increase (p<0.11) in cows fed the MAS-16 and MAS-33 diets. The apparent digestibility of NDF in cows fed the MG diets were higher (p<0.05) than in cows fed the CON diet, with MAS-50 being the highest (p<0.01. The apparent digestibility of crude protein was higher (p<0.05) in cows fed the MAS-50 diet in comparison to cows fed the CON diet. In conclusion, the inclusion of MG silage in lactating dairy cow’s diet had no effects on cow’s feed intake, milk production or milk composition but improved the digestibility of nutrients. The MG silage may replace 50% of dietary corn silage-alfalfa hay mix in a lactating dairy cows ration without any adverse effects on lactating dairy cow’s performance.