Alterations in sheep peripheral blood mononuclear cell proliferation and cytokine release by polyunsaturated fatty acid supplementation in the diet under high ambient temperature

Abstract

The aim of this study was to investigate the effects of polyunsaturated fatty acid (PUFA) supplementation from different sources in the diet of dairy sheep under high ambient temperatures on ex vivo lymphocyte proliferation and inflammatory responses. The experiment was carried out during summer: 32 Comisana ewes were divided into 4 groups of 8. The FS group was supplemented with whole flaxseed, the AG group was supplemented with Ascophyllum nodosum, the FS+AG group was supplemented with a combination of flaxseed and A. nodosum. The fourth group (CON group) was a control and received a diet containing no supplement. The average maximum temperature was around 33°C during wk 2 and 3, whereas the mean temperature never decreased below 26°C. Following 15 d of treatment with respective diets, peripheral blood mononuclear cells (PBMC) from sheep who received a diet supplemented with A. nodosum had impaired cell proliferation responses and IL-6 production after mitogen stimulation compared with PBMC from FS+AG sheep. In addition, PBMC from AG sheep displayed impaired cell proliferation compared with cells from the CON group. The FS+AG cells produced lower levels of IL-10 than CON cells, and higher IL-6 than AG and CON cells. Results demonstrated that the supplementation with PUFA from different sources in a sheep's diet can influence their immunological responses under high ambient temperatures depending on the composition of fatty acid supplementation. In particular, synergistic effects of different PUFA from flaxseed and A. nodosum, simultaneously administrated in the sheep diet, were observed on activation of inflammation response.

Keywords: cytokine; inflammation; polyunsaturated fatty acid; proliferation; sheep.