Dry matter intake was not affected by treatment, but increased with time for both treatments. Milk yield was unaffected by treatment, but decreased in time as cows advanced in lactation. Protein content of milk was lower for the nitrate diet (3.21 vs. 3.05 ± 0.058%, urea vs. nitrate respectively), but milk protein yield was unaffected by treatment. Other milk constituents were unaffected by treatment or time.