Previous research indicates that high- and low-producing cows don’t always respond the same to supplemental fatty acids in the lactation diet. High-producing cows seem to respond favorably to a blend of palmitic (C16:0) and oleic (cis-9 C18:1) acid, butlow-producing cows respond better to a blend of palmitic and stearic (C18:0) acid. New research from Michigan State University reported in the August Journal of Dairy Science, examines why cows respond differently.
In this study, researchers used milk production as a blocking factor to evaluate whether cows with high and low levels of milk production respond differently to supplemental fat containing 60% palmitic acid plus either 30% oleic or 30% stearic acid. Researchers sought to identify if the production responses seen in previous research were due to fatty acids in general or the result of an individual fatty acid. Cows were 118 days in milk and grouped by milk production; the high group averaged 123 lbs/day and the low group averaged 94 lbs/day. Three commercial products were blended to create the desired ratios of fatty acids. Each fatty acid blend was fed at 1.5% of diet dry matter. Results were analyzed two separate ways, overall response to supplemental fat vs. a control group with no supplemental fat and cow response to palmitic with oleic vs. palmitic with stearic acid.
Results clearly indicate that high-producing cows increase milk production due to oleic acid supplementation and not to stearic acid or 18-carbon fatty acid supplementation in general. High-producing cows fed the 60% palmitic with 30% oleic acid blend had increased yields of 3.5% FCM and preformed fatty acids compared to high-producing cows fed the palmitic with stearic acid blend. However, cows in the low group responded more favorably to the palmitic and stearic acid blend with increased yields of 3.5% FCM, ECM, milk fat and protein, and mixed fatty acid yield. More research is needed to replicate these findings and to better understand how cows use stearic and oleic acids and the optimal fatty acid blend for each group.