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Increased Prostaglandin Response to Oxytocin in Ewes Fed a Diet High in Omega-6 Polyunsaturated Fatty Acids


Diets high in omega-6 polyunsaturated fatty acids (n-6) are associated with increased prostaglandin F (PGF) synthesis in cattle, however, the specific effects on the potential prostaglandin response to an oxytocin challenge in sheep have not been reported. The aim of the current study was to determine whether oxytocin-stimulated PGF was significantly increased when ewes were fed a diet high in n-6 compared with a control diet low in n-6. Merino x Border Leicester ewes (n = 30) received one of two dietary treatments, either high in n-6 (70 % oat grain) or low in n-6 (control diet, 100 % cereal/legume silage). Ewes consumed the diets for 44 days prior to two consecutive oxytocin challenges. Plasma n-6 and PGF metabolite (PGFM) concentrations following oxytocin challenge were greater (P < 0.05) when ewes were fed a diet high in n-6 compared with the control diet. A higher availability of n-6 may have lead to an increased in vivo synthesis of PGF, however, further research is required to determine the exact mechanisms involved.

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Arachidonic acid


Area under the curve


Eicosapentaenoic acid (C20:5n-3)


Fatty acid methyl esters


Limit of detection


Limit of quantification


Omega-3 polyunsaturated fatty acid


Omega-6 polyunsaturated fatty acid


Monounsaturated fatty acids


Prostaglandin metabolite 13,14-dihydro-15-keto PGF


Saturated fatty acids


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We thank Greg Clark, Steven Huckell, Michael Loiterton, Rex Edis, Craig Rodham, the Gulliver family, Jessica Rose, John Broster, and a number of high school work experience students for technical assistance during the collection of samples for the study and Richard Meyer, Peter Hawkins and Jamie Ayton for expert advice regarding the analysis of samples. We also thank John Piltz for valuable contributions in drafting and editing of the manuscript. This study was supported with in-kind contributions of feed analyses from the NSW DPI Feed Quality Service and mineral supplements from AusFarm Nutrition Products. Catherine Gulliver was in receipt of stipends from the Australian Postgraduate Award scheme and the Future Farm Industries Cooperative Research Centre. The authors of this paper did not receive any external funding for the conduct of the study. The authors have all contributed to the production of this manuscript. All contributed to the design and conduct of the study, data interpretation and drafting and editing of the manuscript. This study was conducted without dedicated external funding. This study was supported by in-kind provision of equipment by the Diagnostic and Analytical Systems division of NSW DPI.

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The authors do not have any other financial interests or potential conflicts of interest in connection with this manuscript.

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Correspondence to Edward H. Clayton.

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Gulliver, C.E., Friend, M.A., King, B.J. et al. Increased Prostaglandin Response to Oxytocin in Ewes Fed a Diet High in Omega-6 Polyunsaturated Fatty Acids. Lipids 48, 177–183 (2013).

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  • Prostaglandin
  • Oxytocin
  • FAME
  • Sheep
  • Omega-6
  • Omega-3