Short-term dietary supplementation of fatty acids blends with expected effects on PPAR reveals minor changes in hepatic gene expression of mid-lactation Jersey cows

Supplementation of low to moderate amounts of fatty acids in the diets of mid-lactation dairy cows can be an avenue to increase the energy available to the animal. From a bioactive perspective, fatty acids can also modulate the activation of ligand-dependent nuclear receptors, such as the peroxisome proliferator activated receptors (PPAR), which can in turn play a role in key metabolic and physiological pathways. In prior studies, we demonstrated that several fatty acids activate PPAR in vitro at different doses, with a particular larger activation observed for C12, C16 and C18. In this study, we enrolled a total of 30 mid-lactation dairy cows (182.5 day in milk - DIM, 3.18 body condition score, and 483 kg of BW), and assigned them to one of 5 treatment groups: CTR (no additional fatty acids), FA075 and FA150 (the specified fatty acid blend at a rate of 0.75 lbs/head/d and 1.5 lbs/head/d, respectively), and EB075 and EB150 (a commercial blend of fatty acids at the same dose as our blend). Milk samples were collected during AM and PM milking at -7, 3, 10, and 18 days after the beginning of the experiment, and those from day 18 were used to isolated somatic cells by centrifugation at 2,000g for 15 min, followed by two washes in PBS, and resuspended in PBS-EDTA. Total RNA was isolated using the Trizol protocol with minor modifications.