Effects of alpha‐linolenic acid‐enriched rations on markers of inflammation in dairy cattle

Abstract

α‐linolenic acid (αLA: 18:3 ?3) affects inflammatory responses. The objective of this study was to investigate the effects of αLA‐enriched rations on gene expression of systemic (blood) and local (mammary gland) inflammatory markers in dairy cattle. Camelina (camelina sativa) meal (24.2% αLA) was fed at 0, 3, 6, and 9% (DM basis) replacing canola meal (18:1 ω‐9) to provide rations with incremental concentrations of αLA. Lactating primiparous cows (n=18) were randomly assigned to a treatment sequence in a 4x4 Latin square design. Each period lasted 16 d and milk and blood samples were collected during the final 2 d of each period. Peripheral blood mononuclear (PBMC) and milk cells (MC) were harvested, and RNA extracted and converted to cDNA for quantitative real time PCR analysis. Expression of pro‐inflammatory TNF‐α in MC was linearly reduced (up to 40%) as dietary αLA increased. Expression of pro‐inflammatory markers IL‐1β, IL‐8, and TNF‐α was reduced (29, 20, and 27%, respectively) in PBMC isolated from cows fed 6% camelina meal ration as compared with cows fed 0%. Expression of IL‐6 was, however, increased as dietary αLA increased. Further, mRNA expression of TGF‐β in PBMC was decreased. Dietary αLA linearly increased serum phospholipids and milk αLA contents, and down‐regulated expression of local and systemic pro‐inflammatory markers. Supported by the United Dairymen of Idaho and NIH‐NRRI grant P20 RR15587.