Tom Jenkins, Professor Department of Animal & Veterinary Sciences Rumen Transformations of Lipid

Review of Dietary Lipid Fatty acids are most important lipid fraction. Majority of fatty acids are bound to glycerol as simple or compound lipids. Majority of fatty acids are unsaturated.

Rumen Transformations of Lipid Learning Objectives What happens to dietary lipid as it passes from the diet to the intestines and is metabolized by rumen microorganisms? What are the intermediates and end products that accumulate in the rumen from lipid metabolism? How does lipid transformations in the rumen affect animal performance?

Rumen Transformations of Lipid Compounds Extracted in Fat Test? Biohydrogenation Compound Simple Lipolysis MUFA PUFA Microbial Lipid SynthesisVFA

Rumen Transformations of Lipid How Does Dietary Lipid Change as it Passes Through the Rumen? 47.9 lb. DMI 60% Forage (mainly corn silage, 5 lbs. alfalfa hay) From CPM for Dairy v.3.0.8

Intake 892 g FA (<10% FFA) 2 g C18:0 219 g C18:1 440 g C18:2 37 g C18:3 Rumen Transformations of Lipid Rumen FA Transformations Outflow 876 g FA C18:0 C18:1 C18:2 C18:3 From CPM for Dairy v Large Intestine Small Intestine Rumen Omasum Abomasum Reticulum Esophagus Rumen

CH HHHHHHHHHHHHHHHHH CCCCCCCCCCCCCCCCC HHHHHHHHHHHHH O OH Rumen Transformations of Lipid Biohydrogenation Unsaturated (18:2) Stearic (18:0)

Rumen Transformations of Lipid Biohydrogenation Unsaturated Fat H C H C H H H C H H C H C

Rumen Transformations of Lipid Biohydrogenation H C H C H H H C H H C H C H H

Rumen Transformations of Lipid Biohydrogenation Saturated Fat H C H C H H H C H H C H C H H

Rumen Transformations of Lipid Biohydrogenation Unsaturated (18:2) CLA (18:2) trans (18:1) Stearic (18:0)

Rumen Transformations of Lipid Biohydrogenation Unsaturated Fat H C H C H C H H C H C

Rumen Transformations of Lipid Biohydrogenation H C H C H H C H H C H C

Rumen Transformations of Lipid Biohydrogenation H C H C H C H H C H C CLA

Rumen Transformations of Lipid CLA Intermediates in Digesta Linoleic (18:2) cis–9 trans–11 (18:2) trans–11 (18:1) Stearic (18:0) From Teter, B.B., and T.C. Jenkins In Advances in Conjugated Linoleic Acid Research, Vol. 3

Rumen Transformations of Lipid Point 1–Diet Can Change BH Linoleic Acid (cis–9, cis–12 C18:2) Conjugated Linoleic Acid (cis–9, trans–11 CLA) trans–11 C18:1 Stearic (C18:0) Conjugated Linoleic Acid Isomers trans–C18:1 Isomers Stearic (C18:0) Altered Pathways

Rumen Transformations of Lipid Point 2 MINOR intermediates of biohydrogenation can have MAJOR effects on animal performance and human health

Rumen Transformations of Lipid Impact of Rumen Lipid Metabolism Affects human health Meat and milk higher in saturated fat Bioactive metabolites Anti-carcinogenic Anti-atherogenic Enhance immune system

Rumen Transformations of Lipid Impact of Rumen Lipid Metabolism Affects animal performance Supply of essential fatty acids– reproduction Fatty acid antimicrobial effects– production Bioactive metabolites Milk fat depression

Rumen Transformations of Lipid Question Match each of the below from the list of answers shown on the right. One answer per blank. 1.___ Abbreviation of the major fatty acid consumed by dairy cows 2.___ Increases FFA in rumen contents 3.___ Abbreviation of the CLA normally produced in the rumen 4.___ Greatly reduces the supply of essential fatty acids to body tissues A.Biohydrogenation B.cis–9, trans–11 18:2 C.Lipolysis D.cis–9, cis–12 18:2 E.trans–11 C18:1 F.Peroxidation

Rumen Transformations of Lipid Question Which of the below is the best substrate for the synthesis of CLA in the rumen? A.Omega–9 fatty acids B.Essential fatty acids C.Saturated fatty acids D.None of the above

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