Short communication: Comparison of a palmitic acid-enriched triglyceride supplement and calcium salts of palm fatty acids supplement on production responses of dairy cows.

The objective of our study was to evaluate the effects of feeding a palmitic acid-enriched triglyceride supplement or a calcium salts of palm fatty acid (FA) supplement on nutrient digestibility and production responses of mid-lactation dairy cows. Fifteen Holstein cows (139 ± 39 d in milk) were randomly assigned to treatment sequence in a 3 × 3 Latin square design. Treatments were a control diet (CON; no fat supplement) and 1.5% of FA added either as a palmitic acid-enriched triglyceride supplement (PA-TG) or as calcium salts of palm FA supplement (Ca-FA). Fat-supplemented treatments did not affect dry matter intake (DMI) compared with CON, but Ca-FA reduced DMI compared with PA-TG. Compared with CON, fat-supplemented treatments increased 18-carbon FA digestibility by 2.0 percentage units but did not affect digestibility of total FA or 16-carbon FA. Compared with Ca-FA, PA-TG reduced total FA digestibility by 8.7 percentage units due to a decrease in 16-carbon FA digestibility (21.7 percentage units). Both fat supplements increased neutral detergent fiber (NDF) digestibility compared with CON (3.90 percentage units), and PA-TG tended to increase NDF digestibility by 1.60 percentage units compared with Ca-FA. Compared with CON, fat-supplemented treatments increased milk yield (1.05 kg/d), 3.5% fat-corrected milk yield (2.20 kg/d), and energy-corrected milk yield (1.80 kg/d). Also, PA-TG increased milk fat yield (50 g/d) and milk energy output (1.0 Mcal/d) and tended to increase milk fat content (0.07 percentage units) and energy-corrected milk yield (1.0 kg/d) compared with Ca-FA. Fat-supplemented treatments reduced the yield of de novo milk FA (23 g/d) and increased the yields of mixed (43 g/d) and preformed (52 g/d) milk FA compared with CON. The PA-TG treatment increased the yield of 16-carbon (66 g/d) milk FA compared with Ca-FA, whereas Ca-FA increased the yield of preformed (60 g/d) milk FA. Fat-supplemented treatments increased intake of net energy for lactation by 1.80 Mcal/d, milk energy output by 1.30 Mcal/d, and energy in body reserves by 0.30 Mcal/d compared with CON. The Ca-FA treatment increased energy allocated to body reserves (0.60 Mcal/d), energy partitioning toward body reserves (1.20 percentage units), and body condition score change (0.06 units), and tended to increase body weight change (0.16 kg/d) and body condition score (0.08 units) compared with PA-TG. In conclusion, feeding a palmitic acid-enriched triglyceride supplement increased milk energy output due to increased yields of milk and milk fat, whereas feeding a calcium salts of palm FA supplement increased FA digestibility and energy partitioned to body reserves.