Journal of veterinary internal medicine2005; 18(6); 880-886; doi: 10.1892/0891-6640(2004)18<880:eotodp>;2

Effect of type of dietary polyunsaturated fatty acid supplement (corn oil or fish oil) on immune responses in healthy horses.

Abstract: The objective of this study was to compare effects of dietary polyunsaturated fatty acid supplementation (corn oil or fish oil) on selected immune responses in normal horses. Two groups of horses (n = 5) were randomly assigned a dietary supplement with either 3.0% corn oil or fish oil for a period of 14 weeks. Plasma fatty acid profiles were monitored to ensure uptake of dietary fatty acids. Cell-mediated immunity was assessed by a delayed-type hypersensitivity (DTH) skin test to keyhole limpet hemocyanin (KLH), and humoral immunity was assessed by measuring antibody titers to KLH. Production of prostaglandin E2 (PGE2), expression of tumor necrosis factor-alpha (TNF-alpha), and phagocytosis of latex beads by bronchoalveolar lavage fluid (BALF) cells were also assessed. Lipopolysaccharide (LPS)-stimulated BALF cells from horses fed corn oil showed a higher production of PGE2 compared with those from horses fed fish oil at 6 and 12 weeks. Production of TNF-alpha by LPS-stimulated BALF cells was higher in both groups of horses at 6, 8, and 12 weeks compared with pretrial values, and phagocytic activity of BALF cells was higher at 8 and 12 weeks, however, there were no differences between the 2 groups of horses. The DTH skin test and antibody titers to KLH revealed no differences between horses fed corn or fish oil. Based on these studies, dietary polyunsaturated fatty acids modulate the inflammatory response of horses. Both fatty acid supplements increased production of the proinflammatory cytokine TNF-alpha, whereas only corn oil increased production of the proinflammatory eicosanoid PGE2 by LPS-stimulated BALF cells. It is possible that fish oil, because it did not increase production of PGE2, could have value in the treatment of equine recurrent airway obstruction or other equine inflammatory diseases.
Publication Date: 2005-01-11 PubMed ID: 15638273DOI: 10.1892/0891-6640(2004)18<880:eotodp>;2Google Scholar: Lookup
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  • Clinical Trial
  • Journal Article
  • Randomized Controlled Trial
  • Research Support
  • Non-U.S. Gov't


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This research investigated the effects of corn oil and fish oil, both types of polyunsaturated fatty acids, on the immune responses in horses, concluding that both fats might modulate inflammation, but their effect on specific immune responses varies.

Dietary Supplement Assignment

In the study, two randomized groups of horses (five in each group) were assigned to consume a dietary supplement of either 3.0% corn oil or fish oil for 14 weeks. This assignment was part of the study’s investigative process to understand how each polyunsaturated fatty acid could influence the horses’ immune responses and inflammatory factors.

Immune Response Monitoring

Several immune responses were monitored to assess the influence of these dietary supplements. Key factors included:

  • Plasma fatty acid profiles: These were monitored to determine whether horses were effectively absorbing the dietary fatty acids from the supplements.
  • Cell-mediated immunity: This was evaluated through a delayed-type hypersensitivity (DTH) skin test utilizing keyhole limpet hemocyanin (KLH), a type of protein used to trigger an immune response.
  • Humoral immunity: This refers to antibody-mediated immunity and was evaluated by measuring antibody titers—concentration levels—to the KLH protein.

Assessing Inflammatory Responses

The study also examined several inflammatory responses, including:

  • Prostaglandin E2 (PGE2) production: Compared between horses fed on corn oil and those on fish oil diet. The corn oil diet showed higher PGE2 production, an inflammatory substance.
  • Tumor necrosis factor-alpha (TNF-alpha) expression: Both diets led to higher TNF-alpha production, a protein involved in systematic inflammation, at weeks 6, 8, and 12, in comparison to pretrial values.
  • Phagocytosis of latex beads: The study monitored the ability of bronchoalveolar lavage fluid (BALF) cells to engulf and absorb foreign materials, in this case, latex beads. Both diets resulted in increased phagocytic activity at weeks 8 and 12, but there were no significant differences between the two groups.

Interpreting the Findings

  • Both dietary polyunsaturated fatty acids led to some modulation of inflammatory responses. However, only corn oil increased the production of PGE2, a proinflammatory substance.
  • Neither diet led to observable differences in the DTH skin test and antibody titers to KLH, suggesting similar effects on cell-mediated and humoral immunity.
  • The researchers suggested that because the fish oil diet didn’t raise PGE2 production, it may have potential use in treating equine recurrent airway obstruction or other inflammatory diseases in horses.

Cite This Article

Hall JA, Van Saun RJ, Tornquist SJ, Gradin JL, Pearson EG, Wander RC. (2005). Effect of type of dietary polyunsaturated fatty acid supplement (corn oil or fish oil) on immune responses in healthy horses. J Vet Intern Med, 18(6), 880-886.<880:eotodp>;2


ISSN: 0891-6640
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 18
Issue: 6
Pages: 880-886

Researcher Affiliations

Hall, Jean A
  • Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802, USA.
Van Saun, Robert J
    Tornquist, Susan J
      Gradin, Joseph L
        Pearson, Erwin G
          Wander, Rosemary C

            MeSH Terms

            • Animals
            • Bronchoalveolar Lavage Fluid / cytology
            • Corn Oil / administration & dosage
            • Corn Oil / pharmacology
            • Dietary Fats / administration & dosage
            • Dietary Fats / pharmacology
            • Dietary Supplements
            • Dinoprostone / biosynthesis
            • Fatty Acids, Unsaturated / administration & dosage
            • Fatty Acids, Unsaturated / pharmacology
            • Female
            • Fish Oils / administration & dosage
            • Fish Oils / pharmacology
            • Horses / immunology
            • Immune System / drug effects
            • Phagocytosis / drug effects
            • Treatment Outcome
            • Tumor Necrosis Factor-alpha / biosynthesis


            This article has been cited 3 times.
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            2. Liu C, Cook FR, Cook SJ, Craigo JK, Even DL, Issel CJ, Montelaro RC, Horohov DW. The determination of in vivo envelope-specific cell-mediated immune responses in equine infectious anemia virus-infected ponies.. Vet Immunol Immunopathol 2012 Aug 15;148(3-4):302-10.
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            3. Khol-Parisini A, van den Hoven R, Leinker S, Hulan HW, Zentek J. Effects of feeding sunflower oil or seal blubber oil to horses with recurrent airway obstruction.. Can J Vet Res 2007 Jan;71(1):59-65.
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