Several forms of protected fats are common in dairy cow rations. The objectives of this study were to determine the effects of supplementation of saturated fatty acid (SFA; 70–80% C16 and 5–10% C18) in the form of triglycerides (TG), as compared with calcium salt of free fatty acids (CSFA; contained 44% C16, 40% C18:1 and 9.5% C18:2), on milk and milk solids yields, efficiency and digestibility. Twenty-eight multiparous cows were fed a basal diet supplemented either with (on DM basis): (i) SFA - 1.2% SFA (~350 g/cow/d), or (ii) CSFA - 1.4% CSFA (~440 g/cow/d). The supplements were balanced according to fat content (SFA – 99% fat vs. CSFA – 84% fat). Data were analyzed using the PROC MIXED model of SAS. Milk yield of the SFA cows was 3% lower (46.2 vs. 47.6 kg/d; P < 0.001), and fat corrected milk (4%) was 4.5% lower than in CSFA cows. No difference in milk-fat content was observed, but milk-protein content was higher in the SFA cows. No differences in DMI or efficiency calculations between groups were observed. The ruminal pH and ammonia concentrations were similar between groups, while acetate concentrations and acetate:propionate ratio were greater for the CSFA cows. The apparent total track digestibility of all dietary components was lower in the SFA than CSFA cows: DM - 55.8% and 62.0% (P < 0.001); fat - 58.1% and 70.5% (P < 0.001); NDF - 43.0% and 47.8% (P < 0.02), respectively. SFA did not depress milk protein, which would seem an important advantage of the SFA over CSFA. Because supplements in the diet were balanced for their fat content, the lower yields observed in the SFA cows could be due to probable overestimation of the energy value of the SFA supplement, which resulted in lower inclusion level of fat (and energy) in the SFA than CSFA diet. The lower digestibility of all dietary components as observed for the SFA, is probably due to the effects of the degree of saturation and the form of the SFA (highly saturated TG). This leads to the conclusion that although the SFA supplement in the form of TG contains 99% fat comparing to 84% in the CSFA, the net energy for lactation value for SFA might be similar or lower than that of CSFA, mainly because of lower digestibility.