Gross energy intake was not affected by treatment, but increased as the experiment progressed (Table 4). Energy lost in methane production was lower for the nitrate diet and increased during the experiment for both treatments. The energy lost in urine and feces and ME intake (MEI) were unaffected by treatment. Although MEI was not affected by treatment, the MEI:GEI ratio was elevated as a consequence of nitrate feeding (57.3 vs. 58.6 ± 0.70%, urea vs. nitrate, respectively). Calculated heat production was unaffected by treatment, but increased over time. Milk energy yield was unaffected by treatment or time. Despite the higher MEI:GEI ratio, energy retention (ER) was not increased for the nitrate treatment. Apparent total-tract digestibility of NDF, starch, and crude fat were unaffected by treatment.