Excess dietary phosphorous (P) in dairy cows diet may result in increased excretion of this mineral. Additionally, P accumulation in the soil may be a result of high concentrations of P when manure is applied to cropland. The objective of this study was to evaluate P intake, digestibility and excretion when dairy cows consumed rations containing reduced fat distillers grains (RFDDGS). Data from this study originated from an energy balance study in which RFDDGS was included at 28.8% of the ration DM. In this study, corn was reduced from 22.9 to 8.95% and soybean meal was reduced from 14.8 to 0% of the ration DM in the control and co-product (Co-P) diet, respectively. The study included 8 Holstein (BW = 693.8 ± 12.9 kg) and 8 Jersey (BW = 429.1 ± 13.0kg) multiparous, lactating cows (93 ± 20 DIM) in a repeated switchback design. The concentration of P in the test treatments were 0.44% and 0.59% ± 0.01% DM for the control and Co-P diet, respectively. The intake and excretion of P was estimated through feed sampling and total collection of feces. All feed and fecal samples were analyzed for P. Concentration of P in feces was lower in control diet compared with Co-P (0.97 vs. 1.27 ± 0.05%, respectively; P < 0.01). Excretion of P was less for cows fed the control diet compared with the Co-P diet (62.34 vs. 89.70 ± 3.82 g/d, respectively; P < 0.01). The excretion of P per kg of milk yield was higher in cows fed Co-P diet compared with control diet (21.7 and 15.8 ± 1.29 g/kg, respectively; P < 0.01). There was no difference between Holstein and Jersey in concentration of P in the feces (1.16 vs. 1.08 ± 0.07%, respectively; P = 0.36), digestibility (32.3 versus 29.0 ± 2.83%, respectively; P = 0.40) and P efficiency (19.4 vs. 18.0 ± 1.63g/kg, respectively; P = 0.55) across treatments. Results of this study suggest that rations formulated containing RFDDGS should be adjusted for P to reduce P excretion by dairy cows.