1. Triacylglycerol Triglycerides R-COO-CH 2 R-COO-CH R-COO-CH 2 Triglycerides found in seeds and animal adipose. Diglycerides found in plant leaves, one fatty acid is replaced by sugar (galactose).

2. Most Common Fatty Acids in Di- and Triglycerides Fatty acidCarbon:Double bondsDouble bonds Myristic14:0 Palmitic16:0 Palmitoleic16:1 Cis-9 Stearic18:0 Oleic18:1 Cis-9 Linoleic18:2 Cis-9,12 Linolenic18:3 Cis-9,12,15 Arachidonic20:4 Cis-5,8,11,14 Eicosapentaenoic20:5 Cis-5,8,11,14,17 Docosahexaenoic22:6 Cis-4,7,10,13,16,19 CH 3 (CH 2 ) n COOH

3. Triglyceride Containing Linoleic Acid Omega-6

4. Linolenic Acid Omega-3

5. Fatty Acid Isomers

6. Lipid Content of Feeds Forages Fat content is low: 1 to 4% of dry matter High proportion of linolenic acid (18:3) Diglycerides in fats of leaves Grains Fat content variable: 4 to 20% of dry matter High proportion of linoleic acid (18:2) Triglycerides in oils of seeds

7. Lipid Digestion - Rumen DigalDiglyMonogalDigly Galactose PropionateDiglyceride Glycerol TriglyerideFatty acids Saturated FA CaFACa ++ Feed particles  -galactosidase  -galactosidase Lipase Anaerovibrio lipolytica H + Reductases Lipase

8. Fat Digestion Digestibility influenced by: Dry matter intake Decreases with greater intake Amount of fat consumed Digestibility decreases 2.2% for each 100 g of FA intake (Response is variable) Degree of saturation Digestibility decreases with increased saturation Maximal digestion with fats having Iodine values greater than 40

9. 1. Minimal degradation of long-chain fatty acids in the rumen Fatty acids not a source of energy to microbes 2. Active hydrogenation of unsaturated fatty acids 3. Microbial synthesis of long-chain fatty acids in the rumen (15g/kg nonfat org matter fermented) 4. No absorption of long chain fatty acids from the rumen More fat leaves the rumen than consumed by the animal Lipids leaving the rumen 80 to 90% free fatty acids attached to feed particles and microbes ~10% microbial phospholipids leave the rumen Small quantity of undigested fats in feed residue Lipid Metabolism - In the Rumen

10. Synthesize C 18:0 and C 16:0 in 2:1 ratio using acetate and glucose (straight-chain even carbon #). If propionate or valerate used, straight-chain odd carbon fatty acids synthesized. Branched-chain VFA used to produce branched chain fatty acids. About 15 to 20% of microbial fatty acids are mono- unsaturated. No polyunsaturated fatty acids are synthesized. Some incorporation of C 18:2 into microbial lipids. Microbial Fatty Acid Synthesis

11. Hydrogenation of Fatty Acids in the Rumen Polyunsaturated fatty acids (all cis) Isomerase (from bacteria) Needs free carboxyl group and diene double bond Shift of one double bond (cis & trans) Hydrogenation Hydrases (from bacteria, Hydrogenated fatty acid mostly cellulolytic) (stearic and palmitate)

12. Hydrogenation of Fatty Acids in the Rumen All unsaturated fatty acids can be hydrogenated Monounsaturated less than polyunsaturated 65 to 96% hydrogenation Numerous isomers are produced Biohydrogenation is greater when high forage diets fed Linoleic acid depresses hydrogenation of FA

13. Conjugated Linoleic Acid - Rumen Most Common Pathway (High Roughage) Linoleic acid (cis-9, cis-12-18:2) Conjugated linoleic acid (CLA, cis-9, trans-11- 18:2) Vaccenic acid (Trans-11-18:1) Stearic acid (18:0) Cis-9, trans-12 isomerase Butyrivibrio fibrosolvens

14. CLA Isomers - Rumen (High Concentrate) Low Rumen pH Linoleic acid (cis-9, cis-12-18:2) Cis-9, trans-10 isomerase CLA Isomer (trans-10, Cis-12-18:2) This isomer is inhibitory to milk fat synthesis. Trans-10-18:1

15. Linolenic Acid – Oleic Acid Linolenic acid (cis-9, cis-12, cis-15-18:3) (Cis-9, trans-11, cis-15-18:3) Trans-11, cis-15-18:2 Trans-11-18:1 (vaccenic acid) Oleic acid cis-9 (18:1)Stearic acid (18:0)

16. CLA absorbed from the intestines available for incorporation into tissue triglycerides. Reactions from linoleic acid to vaccinic acid occur at a faster rate than from vaccinic acid to stearic acid. Therefore, vaccinic acid accumulates in the rumen and passes into intestines where it is absorbed. Quantities of vaccinic acid leaving the rumen several fold greater than CLA.

17. Conversion of Vaccinic Acid to CLA In mammary gland and adipose Trans-11-18:1 CLA, cis-9, trans-11 18:2 Stearoyl CoA Desaturase ‘  9 -desaturase’ This reaction probably major source of CLA in milk and tissues from ruminants. Also transforms PalmiticPalmitoleic StearicOleic

18. Potential Value of CLA in Foods of Ruminant Origin Anticarcinogenic Lab animals given chemicals to cause cancer Reduce atherosclerosis Direct evidence with rabbits Indirect evidence with humans Reduce fat accumulation in the body Laboratory animals and pigs Evidence not conclusive with humans

19. CLA Content of Foods CLA isomers cis 9, trans 11 Foodmg/g fat% Beef4.385 Pork0.682 Chicken0.984 Milk5.592 Colby cheese6.192 Corn oil0.239

20. Increasing CLA in Foods of Ruminant Origin Grazing grass increases CLA concentration in meat and milk from ruminants Feeding Ca-salts of unsaturated fatty acids Processing full fat soybeans to release oil Extrusion, roasting, heating temperature Feeding fish oil Feeding high oil corn - minimal effects Control milk: 3 to 4 mg CLA/g fatty acids Experimental milk: 5 to 25 mg CLA/g fatty acids Less response if high-concentrate diets are fed

21. Increase in trans-10, cis-12-18:2 CLA isomer when unsaturated oils fed in high-grain diets Low rumen pH seems to increase trans fatty acids in the rumen Decrease milk fat Trans fatty acids increase in low fat milk High Concentrations of CLA Isomers

22. Concentrations of Omega-3 and Omega-6 Fatty Acids with Time Fed Grain - Cattle Duckett et al., 1993

23. Ratio of Omega-6:Omega-3 Fatty Acids with Time Fed Grain - Cattle

24. Stearoyl CoA Desaturase (  9 -Desaturase) in Wagyu and Holstein Steers WagyuHolstein Muscle3.30.8 Adipose132.139.5 Mono Unsat, %57.353.4 Yang et al., 1999

25. cis9 trans11 CLA Concentrations in Milk from Different Farms in Northeast Iowa

26. Oleic Acid in Milk and Tissues Oleic acid (18:1) is predominant fatty acid in ruminant fat. Stearic acidOleic acid Delta-9 desaturase Delta-9 desaturase found in ruminant adipose and mammary gland

27. Fatty Acid Concentrations % by Wt FA Alf Grass CornSBBacPro Beef Mut 14:00.91.100.13.91.53.72.6 16:033.916.910.910.331.037.824.223.0 18:03.82.01.83.815.013.513.525.8 16:11.22.500.24.06.86.01.9 18:13.03.424.122.86.011.543.737.9 18:224.013.258.051.02.76.32.62.2 18:331.061.30.76.81.04.7

28. Postruminal Fat Digestion and Absorption Fatty acids from the rumen mostly saturated No absorption of fatty acids from the rumen Fatty acids attached to feed particles, Ca and microbes dissociate in the acid environment of the abomasum pH of duodenum and jejunum remains acidic in ruminants - Affects solubility of fatty acids in aqueous environment Fatty acid emulsification and micelle formation in the small intestine is essential for efficient absorption Fatty acids absorbed predominantly from the jejunum into lymph

29. IntestineLiverPancreas Free fatty acids Bile saltsMicelle Phospholipases LecithinLysolecithin PhospholipidsFatty acids Epithelial cell TriglyceridesLymph Fatty acidsChylomicrons x Fatty Acid Absorption Bile of ruminants contains predominantly taurine-conjugated bile acids rather than glycine conjugate. The taurine conjugate is more effective at acid pH

30. In digestion and metabolism of fats: No energy lost as methane No energy lost in the urine So: Digestible energy = metabolizable energy Energy value of fat determined by digestibility Digestibility of supplemental fats is variable Use of metabolizable energy from fat is about 80% or ME x 0.80 = Net Energy Gross Energy Tallow - 9.2 Mcal/kg Free fatty acids - 9.39 Mcal/kg Ca salts of free fatty acids - 8.03 Mcal/kg Energy Value of Fats

31. Effects of Fats on Rumen Fermentation Effects of adding fat to ruminant diets Reduced feed intake Reduced fiber digestion Reduced milk fat Increase propionate/acetate ratio Polyunsaturated fats more inhibitory than saturated fats Feeding oil seeds of polyunsaturated fats less inhibitory Up to 3% of diet as tallow or yellow grease can be fed without major effects

32. Mechanism of Inhibition Lipids coat feed particles Interfere with microbial attachment Interfere with attachment of enzymes Complex Ca Direct antimicrobial effects Cytotoxic effects on cell membranes Interfere with energy metabolism Free carboxyl group needed Triglycerides less toxic than free fatty acids Ca salts of fatty acids less toxic

33. Metabolic Pathways in Ruminant Adipose Adipose CellTriglycerides Glycerol-3-P Free fatty acids Glycerol NADPH Acetate Glucose Glucose GlycerolNEFA VLDLAcetate Bloodtriglycerides Lipoprotein lipase

34. Adding Fat to Ruminant Diets Ruminant feeds normally contain low levels of fats or oils - usually 2 to 4%. Why add fat? Increase energy density in the diet Fat 2.5 times more energy Increase milk production or gain (Benefits should be greater than costs) Secondary benefits: Improve diet and pellet characteristics Reduces dust Lubricate feed processing equipment Pellet mills, mixers, etc

35. Adding Fat to Ruminant Diets Need to add proper level and kind of fat How much fat is in basal diet Kind of fatty acids in basal diet Level of production Potential limitations Hydrogenated fats less digestible Unsaturated fatty acids depress fiber digestion Decreased feed intake Produce trans fatty acids and reduce milk fat Usually limit the quantity of added fat to less than 5% of total diet of ruminants

36. Types of Fat Fed to Ruminants Rumen inert (Protected) Ca salts of fatty acids, hydrogenated fats Have little if any effects on fiber digestion in the rumen Sold commercially in dry form Easy to mix Expensive source of fat Unprotected Animal fats (tallow, grease, etc) More difficult to mix - Cold weather - Melt fats Most commonly used as feed Plant oils (soybean, corn, etc) Unsaturated fatty acids depress fiber digestion Usually cost prohibitive Whole oil seeds Soybeans, cotton seeds, high-oil corn Oils are not as readily available Less effect on rumen fermentation Easiest for smaller producers to feed

37. Finishing Steers - Rolled Barley 305 kg steers fed 88% concentrate diet Blended fats: yellow grease and animal + vegetable

38. Finishing Steers - Rolled Barley Steers fed 88% concentrate diet Blended fats: yellow grease and animal + vegetable

39. Finishing Steers - Rolled Corn 350 kg steers fed 93% concentrate diet

40. Adding Fat to Lactation Diets Factors affecting response to supplemental fat: Basal diet Digestibility of corn silage affected more than other roughages Stage of lactation Energy balance Greater response when cow needs energy Composition of added fat Unsaturated - saturated fatty acids Availability of fat in the rumen Amount of supplemental fat Response is curvilinear

41. Lactation Diets Supplement during peak lactation From 7 - 8 weeks to 11 - 15 weeks Amount to feed Milk production reaches maximal efficiency when fatty acids contribute 16% of ME Equates to about 600 to 700 g of supplemental fat per day Will support about 3.5 kg increase in milk Total dietary fat should not exceed 6 to 7% of dietary DM

42. Lactation Diets Full fat oil seeds Available oil increased with processing Extruding - heat Usually minimal effects on rumen fermentation Unprotected fats Tallow - saturated fatty acids Add up to amount that will not affect rumen fermentation Protected fats Use if addition of unprotected fat does not meet the energy needs More expensive

43. Adding Fat - Lactation 50% corn silage

44. Adding Fat - Lactation Corn silage, alfalfa hay & cottonseed hulls Choice white grease

45. Adding Fat - Lactation Corn silage, alfalfa hay & cottonseed hulls Choice white grease

46. Effects of Supplemental Fat on Reproduction Variables Animal: Body condition score, age (parity), nutrients available Type of fat: Digestibility, fatty acid composition, quantity of fat Research is inconclusive on response to added fat, unless control animals are energy deficient Response Metabolic hormones – Insulin, growth hormone, IGFs Cholesterol – Progesterone concentrations LH secretion and follicular development Prostaglandin synthesis –PGF 2 