In order to get the information on the most economic feeding of dairy cows, the study was conducted with the different ratios of roughage to concentrate feed upon milk production, changes of body weight and pH of rumen fluid using 3×3 Latin square design. Three different feed ratios have been tested with the following proportions of roughages to concentrate; 40% : 60%(Treatment A), 50% : 50%(Treatment B) 60% : 40% (Treatment C) calculated on total digestible nutrient basis. The results obtained are as follows: 1. Dry matter intake per day during the experimental period among three treatments showed no differences. 2. Milk yield of Treatment A feeding lot tended to give higher yield than that of treatments B and C feeding lots, but the difference was not statistically significant. And production of 4% fat corrected milk was not different among the diets of treatment A, B and C. 3. Milk fat content of Treatment A feeding lot seemed to be lower than that of treatment B and C feeding lots, but the difference was not significant. 4. Content of solids-not-fat of milk was not different among treatments of A, B and C. 5. pH of rumen fluid showed no difference among the different treatments. 6. The daily water consumption per cow was higher in treatment A feeding lot than that of treatments B and C feeding lots, but the difference was not significant. 7. Treatment A gave the most increase in body weight followed by treatment B and treatment B gave the least increase in body weight during the experimental period, but the difference was not significant.