This study aimed to determine the effects of a total mixed ration (TMR) containing dried sweet potato on the dry matter intake, rumen fermentation, and lactation performance in lactating dairy cows. Four Holstein cows in late lactation were used in a 2×2 crossover design to examine the effect of 2 TMRs : 1) DSP-TMR containing dried sweet potato(DSP) (8.6% on a dry matter basis) and 2) FB-TMR containing flaked barley (FB) (10% on a dry matter basis). The cows were housed in a free-stall barn. There were no statistical differences in mean daily dry matter intake, ruminal pH and protozoal number or mole percentage of rumen volatile fatty acids and A/P ratio between the treatments. Though there were no statistical differences in milk yield and milk fat%, milk protein% tended to be higher in the FB than the DSP. These results suggested that DSP was equal to FB in mean daily dry matter intake, milk yield and milk fat%, and rumen fermentation. However, from the viewpoint of milk protein%, there is room for improvement of feeding value of DSP.
