Fifty-two multiparous cows were used in a randomized complete block design experiment and assigned to either a control diet containing no supplemental fat (CON) or a C16:0 supplemented diet (PA) that was fed either from calving to 24 DIM (fresh period) or from 25 to 67 DIM (peak period). Fresh diets were formulated to contain (% DM) 17% CP, 30% NDF, 24% forage NDF, and 24% starch. Peak diets were formulated to contain (% DM) 17% CP, 29% NDF, 19% forage NDF, and 26% starch. The C16:0 supplement (85% C16:0), added at 1.5% of diet DM, replaced soyhulls in the CON diets. During the fresh period, PA did not affect DMI (21.5 vs. 21.6 kg/d, P = 0.92) or milk yield (47.7 vs. 46.3 kg/d, P = 0.38) compared with CON. In contrast, compared with CON, PA increased milk fat content (4.89 vs. 4.48%, P = 0.01) and yield (2.29 vs. 2.01 kg/d, P < 0.01), milk protein yield (1.60 vs. 1.53 kg/d, P = 0.03), and ECM (56.6 vs. 51.9 kg/d, P = 0.02). PA decreased BW (668 vs. 709 kg, P = 0.05), BCS (3.25 vs. 3.34, P = 0.04), plasma insulin (0.21 vs. 0.24 μg/L, P = 0.05), and increased plasma NEFA (0.65 vs. 0.59 mEq/L, P = 0.03) compared with CON. A treatment by day interaction was detected for BW (P = 0.05) and BCS (P = 0.07) due to PA only decreasing these variables after 10 DIM compared with CON. During the peak period, compared with CON, PA did not affect DMI (29.9 vs. 30.2 kg/d, P = 0.68), but increased milk yield (58.0 vs. 54.6 kg/d, P = 0.01), milk fat content (3.88 vs. 3.67%, P < 0.01) and yield (2.27 vs. 2.06 kg/d, P < 0.01), milk protein yield (1.80 vs. 1.66 kg/d, P = 0.04), and ECM (62.3 vs. 57.8 kg/d, P < 0.01). Compared with CON, PA reduced plasma insulin concentration (0.25 vs. 0.32 μg/L, P = 0.05), but did not affect plasma NEFA concentration (0.35 vs. 0.32 mEq/L, P = 0.41) or BW (673 vs. 684 kg, P = 0.93). There were no interactions between feeding PA and the time that supplementation started for production variables. Our results demonstrate that supplementing C16:0 during early lactation increases ECM without changes in DMI. Feeding PA may increase BW loss during the fresh period, but not during the peak period.