This study was conducted to evaluate fat supplements differing in fatty acid (FA) composition on nutrient digestibility, milk yield and composition, and milk FA profile in dairy cows. Twenty-four Holstein cows (149 ± 85 d in milk, 35.6 ± 6.29 kg/d milk yield and 671 ± 93.4 kg body weight) were distributed in 8 Latin squares according to parity number, milk yield and days in milk, and enrolled in a replicated 3 × 3 Latin square experiment with 21-d periods. Cows within block were randomly assigned to treatment sequences containing: 1) control (CON), no fat supplement and 2.44% ether extract (EE, dry matter basis (DM)); 2) calcium salts of palm oil (CSPO), CSPO at 2.60% diet DM and 4.49% EE diet DM; and 3) encapsulated fatty acids (EFA), EFA at 2.60% diet DM and 4.30% EE diet DM. Fatty acids from EFA are derived from soybean oil, palm oil, and tallow. The primary differences in FA profiles between CSPO and EFA were related to stearic acid (4.26 and 31.7 g/100 g FA, respectively), oleic acid (32.7 and 8.80 g/100 g FA, respectively), and linoleic acid (8.81 and 19.1 g/100 g FA, respectively). Fat supplements were included in the concentrate mix and cows were fed a total mixed ration (48:52 of forage to concentrate ratio). Data were analysed using mixed models and treatment differences were evaluated by orthogonal contrasts (CON vs. fat-supplemented diets and CSPO vs. EFA). Dry matter intake and digestibility were not affected by treatments; however, EE intake and digestibility were higher with the inclusion of fat supplements. Fat supplementation increased milk yield (34.1, 35.8, and 35.9 kg/d for CON, CSPO and EFA, respectively). Fat supplementation also improved the yield of milk components and feed efficiency. Cows fed EFA had higher milk protein concentrations compared to those fed CSPO. Cows fed fat supplements exhibited higher concentrations of unsaturated FA and lower concentrations of de novo FA in milk compared to CON group. The concentration of de novo and odd-chain FA in the milk of cows fed CSPO was lower than in those fed EFA. Cows fed EFA had lower concentrations of trans-11 C18:1 and cis-9 C18:1 FA compared to the CSPO group. Fat supplements increased milk yield, feed efficiency and unsaturated FA concentration in milk without affecting DM digestibility. Supplementing cows with either CSPO or EFA resulted in similar performance.
Freitas et al. (Tue,) studied this question.