The Effect of Dietary Fat on Fatty Acid Composition, Gene Expression and Vitamin Status in Pre-Ruminant Calves

Dietary saturated (SFA) and unsaturated fat (UFA) alters fatty acid (FA) composition of various tissues, serum and lipid-soluble vitamins. The objective was to examine the effect of dietary SFA and UFA on adipose, liver, serum, polymorphonuclear (PMN) and peripheral blood mononuclear cells' (PBMC) FA profiles, selected gene expression of inflammatory mediators, and their relation with vitamin content in pre-ruminant calves. Twelve Holstein male calves were randomly assigned to two treatments. Starting 3 d of age, 6 calves on SFA received 120 mL palm oil/d, and 6 calve on UFA received 80 mL flaxseed oil plus 40 mL conjugated linoleic acid. After 50 d, all animals were euthanized and samples were obtained. Gas-chromatography was used to analyze FA composition. High-performance liquid chromatography was used to analyze alpha-tocopherol and retinol in liver tissues as well as alpha-tocopherol, retinol and beta-carotene in serum. Liver and adipose tissue were analyzed for relative gene expression of interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12, interferon-gamma, peroxisome proliferator-activated receptor-gamma, TNF-alpha, retinol binding protein-4 and NF-kappaB. The PBMC were examined for gene expression of IL-1beta, IL-6, TNF-alpha and intercellular adhesion molecule-1; PMN were analyzed for expression of caspase-1, IL-8 receptor and L-selectin (L-SEL). Data were analyzed using the Proc TTEST of SAS with significance declared at P ≤ 0.05. The UFA had greater ?-linolenic acid (?-LA) compared to SFA calves in [non-esterified fatty acid (NEFA), neutral lipid (NL) and phospholipids (PL)] fractions of liver, adipose and serum as well as PBMC and PMN. The higher content of ?-LA in calves fed UFA resulted in greater EPA in all three lipid fractions of serum as well as NL and PL fractions of adipose tissue. In addition, PBMC and PMN had higher EPA in UFA calves. The UFA group however, had lower ?-linolenic acid compared to SFA calves in all three fractions of liver as well as NL and PL fractions of serum. Dietary UFA also increased total PUFA in three lipid fractions of serum and adipose. The lipid-soluble vitamins content in serum was reduced by dietary UFA. Moreover, L-SEL expression was upregulated in calves receiving UFA. This may indicate that UFA supplementation elevated the substrate of PUFA biosynthesis, but possibly degraded the lipid soluble vitamins to protect these FA from oxidation. This may influence the migration of PMN from the blood to tissues, affecting overall inflammatory responses.