What is the Best FA Ratio for Mid-Lactation Cows? 

New dairy research evaluated several fatty acid blends in the diets of mid-lactation cows to determine the optimal ratio that helps high producing, mid-lactation cows maximize production performance. 

Research during the past 15 years has repeatedly demonstrated that not all fatty acids are the same. Each individual fatty acid plays a specific role in the diet and can affect digestibility, metabolism, energy partitioning and milk production in lactating dairy cows. In addition, cow response varies by stage of lactation and level of production.

New research from Michigan State University sought to identify the optimal fatty acid blend of palmitic and stearic acids in the diet of high-producing, mid-lactation cows to maximize production performance. Researchers evaluated cow response to three different ratios of fatty acids: 

  • 30% palmitic (C16:0) + 50% stearic (C18:0).
  • 50% palmitic + 30% stearic.
  • 80% palmitic + 10% stearic.

All fatty acid blends were formulated to contain 10% oleic acid (cis-9 C18:1) and were fed at 1.5% of diet dry matter. The fatty acid blends replaced soyhulls in the control diet. Diets were balanced to contain (% of DM) 31% neutral detergent fiber (NDF), 27% starch and 16.9% crude protein. 

Three commercially available products were used to create the desired fatty acid blends. At the start of the study, cows were producing an average of 114.4 ± 12.8 lbs of milk/day and were 100 ± 23 days in milk. All animals were fed a common diet with no fatty acid supplementation for the first seven days of the study to obtain baseline values for each cow. On day eight animals were assigned to one of the four different treatment groups (control group plus the three fatty acid formulations) for the rest of the 21-day period. 

Results were as follows: 

  • All fatty acid blends increased yields of milk, 3.5% fat-corrected milk (FCM), energy-corrected milk (ECM), milk fat, milk lactose, milk fat content and feed efficiency compared to control cows. 
  • As the amount of palmitic acid increased and stearic acid decreased in the diet DMI, yields of 3.5% FCM, ECM, milk fat and milk fat content all increased. 
  • High-producing, mid-lactation cows responded best to a ratio of 80% palmitic + 10% stearic acids.

These results improve our understanding of how individual fatty acids work in the diet and how they can be used to tailor the nutrition of cows in order to boost production performance and improve efficiency. This study, in addition to other recent research, “supports the use of palmitic acid enriched supplements and suggests there is little to no benefit of high levels of stearic acid in fatty acid supplements” in the diet of mid-lactation high-production cows.   

To learn more about this research go to: https://doi.org/10.3168/jds.2023-23874

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