Dietary (n‐3) Fatty Acids from Menhaden Fish Oil Alter Plasma Fatty Acids and Leukotriene B Synthesis in Healthy Horses

Abstract

The study objective was to determine the effect of feeding corn oil or fish oil to horses on plasma fatty acid profiles and leukotriene B (LTB) synthesis by stimulated peripheral blood neutrophils. Two groups of horses (n = 5) were randomly assigned to diets supplemented with either 3.0% (by weight) corn oil or fish oil for a period of 14 weeks. The ratio of (n‐6) to (n‐3) fatty acids in oil supplements was 68.1:1 for corn oil and 0.12:1 for fish oil. Production of LTB4 and LTB5 by peripheral blood neutrophils stimulated with calcium ionophore A23187 and plasma cholesterol, triacylglycerol, and α‐tocopherol concentrations were measured. At 12 weeks, horses fed fish oil had increased plasma concentrations of eicosapentaenoic acid (27‐fold; 8.5 versus 0.3 g/100 g fatty acids; P < .0001), docosahexaenoic acid (34‐fold; 5.1 versus 0.1 g/100 g fatty acids; P < .0001), and arachidonic acid (8.3‐fold; 4.1 versus 0.5 g/100 g fatty acids; P < .0001) compared with horses fed corn oil. Neutrophils from horses fed fish oil produced 78‐fold (P= .01) more LTB5 and 9.5‐fold (P= .003) more LTB4 compared with predietary levels, and 17.6‐fold (P= .01) and 3.3‐fold (P= .02), respectively, more than horses fed corn oil, and the ratio of LTB5 to LTB4 concentrations was 4.0‐fold (P= .002) higher in horses fed fish oil. This study suggests that dietary polyunsaturated fatty acids modulate the leukotriene inflammatory response of horses. If the ratio of LTB5 to LTB4 concentrations is important in determining how inflammatory processes are mediated, then fish oil supplementation may have value in treatment of equine inflammatory diseases.

Mammary inflammation around parturition appeared to be attenuated by consumption of fish oil rich in n-3 polyunsaturated fatty acids

“…An amplified plasma concentration of n-3 PUFA was observed following FO consumption for 14 days in this study, which agreed well with the previous study in horses by Hall et al [19]. Hall et al [19] also found decreased plasma n-6 FA concentration in the FO-fed horses, but little variation of plasma n-6 PUFA concentration was observed in the FO-fed rats in this study.…”

“…An amplified plasma concentration of n-3 PUFA was observed following FO consumption for 14 days in this study, which agreed well with the previous study in horses by Hall et al [19]. Hall et al [19] also found decreased plasma n-6 FA concentration in the FO-fed horses, but little variation of plasma n-6 PUFA concentration was observed in the FO-fed rats in this study. Noting that the horses used in the study of Hall et al [19] consumed FO for 6 weeks, a shorter consumption period (24 days) in this study may explain the little variation of n-6 PUFA.…”

“…Hall et al [19] also found decreased plasma n-6 FA concentration in the FO-fed horses, but little variation of plasma n-6 PUFA concentration was observed in the FO-fed rats in this study. Noting that the horses used in the study of Hall et al [19] consumed FO for 6 weeks, a shorter consumption period (24 days) in this study may explain the little variation of n-6 PUFA. In addition, it was verified in the present study that substituting SO with FO resulted in higher plasma n-3 PUFA concentration and lower concentrations of SFA and n-6 PUFA.…”

Rapid, Multiwell Colorimetric Assay for Measuring Neutrophil Chemoattractant Activity in Bronchoalveolar Lavage Fluid of Horses with Recurrent Airway Obstruction

“…Equine neutrophils, collected from a healthy horse that was not included in this study, were purified from whole blood with heparin added as an anticoagulant, using a histopaque 1119 density gradient centrifugation protocol as previously described. 14 More than 93% of total cells isolated were neutrophils, and cell viability was greater than 90% based on trypan blue exclusion. These neutrophils were resuspended in Earle's minimum essential medium (EMEM; with 25 mm N-2-hydroxyethylpiperazine-N9-2-ethanesulfonic acid (HEPES) buffer without L-glutamine and phenol red) with 5% heatinactivated fetal calf serum (FCS).…”

Omega-3 fatty acid supplementation in horses

“…In arthritic horses, supplementation with EPA and DHA increased stride length (Woodward et al, 2005) and reduced inflammatory markers (Manhart et al, 2009). In horses, feeding Menhaden fish oil modulated leucotriene synthesis influencing inflammatory conditions (Hall et al, 2004).…”