Effects of elevated subcutaneous fat stores on serum nonesterfied and milk fatty acid profile and peripheral blood mononuclear cells gene expression of pro-inflammatory markers and production measures in periparturient dairy cows

Abstract Text: Dairy cows with greater subcutaneous fat stores release greater concentrations of nonesterified fatty acids (NEFA) into the blood during the periparturient period. The objective of this study was to determine the effect of elevated lipid mobilization during the periparturient period on serum NEFA and milk fatty acid (FA) profile, peripheral blood mononuclear cells (PBMC), gene expression of selected markers of inflammation and production measures. Thirty-four cows were blocked by parity; treatment received a dry cow ration with an additional 10 kg of corn / head per day starting -28 d relative to parturition. The control received the dry cow ration (no additional corn) with 400 mg of monensin / head per day. Immediately postpartum, cows were fasted for 8 h. Serum samples were collected on -28, -7, +1, +6, +15, and +21 d for FA analysis of specific lipid fractions. Milk samples were obtained on +1, +3, +6, +15, and +21 d for composition, yield, and FA analyses. Real-time q-PCR gene analysis for intercellular adhesion molecule 1 (ICAM-1), interleukin (IL) 1β and 6, and tumor necrosis factor-α (TNF-α) was performed on PBMC collected on -28, +3, +12, and +21 d. Data were analyzed as repeated measures analysis of variance using mixed model procedures in SAS (9.3) and significance was declared at P ≤ 0.05. Within serum NEFA fraction, C16:1, sum of C18:1 trans, and C18:3n3 were greater in control than in treatment prepartum, but no significance was detected in postpartum. In contrast, sum of C18:1 trans was greater in treatment compared with that of control during postpartum period. Serum concentration of C20:4n6 tended to be greater in treatment compared with that of control (1.12 vs 0.86 ± 0.11%; P = 0.06). In milk fat, C16:1 and C18:2 cis were greater for treatment and C15:0, C18:3n3 and C22:2 were lower for treatment compared to with control. Gene expression for IL-1β in PBMC was greater for control, whereas ICAM-1, IL-1β, IL-6, and TNF-α were greater in primiparous than multiparous cows, without a detectable treatment effect. Prepartum, control cows consumed more feed than treatment. Postpartum intake indicated a marginal treatment × time interaction, with intake wavering until d +11 and treatment consuming relatively more thereafter. In summary, increased subcutaneous fat stores altered FA profile of serum NEFA fraction and milk as well as gene expression of PBMC in periparturient dairy cows.

Keywords: lipid mobilization, fatty acid profile, peripheral blood mononuclear cells