Chapter 8 Lipids.
G. G. PEARL, 1995
The term lipid includes the fats and the oils. Lipids are important constituents of every cell of the body. Their content in feedstuffs varies considerably. As a component of livestock feed, lipids are generally in the form of triacylglycerol (formerly named triglyceride). Triacylglycerol in feed may deteriorate, so it is important that livestock feeders be familiar with the terms and processes that are used to assess lipid quality. In this chapter, the digestion and absorption of ingested lipid in feed is also described.
IMPORTANCE OF LIPIDS
Lipids are a diverse group of molecules that are insoluble in water but soluble in nonpolar solvents such as ether, chloroform, and benzene. Like carbohydrates, lipids are compounds of carbon, hydrogen, and oxygen, but they contain a much higher percentage of hydrogen than carbohydrates. The lipid group includes triacylglycerol, phospholipids, glycolipids, and lipoproteins. From the standpoint of animal nutrition, the triacylglycerols are the most important lipid.
[FIGURE 8-1 OMITTED]
In the body, lipids serve as structural components of membranes, protective coatings on the surface of animals, cell-surface components concerned with cell recognition and tissue immunity, and storage and transport forms of metabolic fuel. In the feed, lipids increase energy density, reduce dustiness, enhance palatability, lubricate mixing and handling equipment, and act as a medium for dietary sources of the fat-soluble vitamins.
A challenge faced by everyone involved in feeding livestock is to meet the energy requirement for growing animals and high producers. The first step in boosting energy content of herbivore rations is to substitute grains for forages. But this measure alone does not achieve the performance potential of some animals, even with the highest level of grain that can be fed without negatively affecting animal health. In comparison to carbohydrate and protein, fat contains more than twice the amount of energy per pound (Figure 8-1). Adding fat will increase energy density in rations for all types of domestic animals.
STRUCTURE OF TRIACYLGLYCEROLS
Triacylglycerols are glycerol esters of fatty acids. As part of the triacylglycerol, each fatty acid is an acyl group (Figure 8-2). Glycerol is a three-carbon compound with hydroxyl (--OH) groups attached to each carbon. Each of these --OH groups is available to bond to a fatty acid. The term ester refers to the type of linkage between the --OH group of the glycerol and the fatty acid (Figure 8-3). A glycerol molecule whose three--OH groups have participated in bonds with long-chain fatty acids is called a triacylglycerol.
The glycerol is often referred to as the "backbone" of the triacylglycerol molecule. There are many possible fatty acids that may be attached to the glycerol backbone. The nature of these fatty acids gives each triacylglycerol its own unique characteristics. When triacylglycerols contain a high percentage of saturated fatty acids such as ruminant fat or pork fat (lard), they are usually solid at room temperature. Triacylglycerols that are solid at room temperature are generally referred to as fats. Triacylglycerols that contain a high percentage of unsaturated fatty acids such as corn oil, soybean oil, and canola oil are usually liquid at room temperature. Triacylglycerols that are liquid at room temperature are generally referred to as oils. Triacylglycerol as a feed ingredient is usually referred to as simply fat and that is the convention that will be used from this point forward in this text.
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Biohydrogenation: Saturation of fatty acids by microbial activity. Bypass or inert fats: A fat that when fed to a ruminant animal, has no effect on rumen microbe activity.
Chain length: Number of carbons in a fatty acid.
Ester: The type of bond used in the attachment of a fatty acid to glycerol.
Fatty acid: Fatty acids are examples of carboxylic acids, C[H.sub.3] --[(C[H.sub.2]).sub.n]--COOH.
Free fatty acid: A fatty acid that is not attached to glycerol; usually used in reference to fat quality.
Hydrogenated fat: A fat whose component fatty acids have been chemically saturated.
Iodine value: Ameasure of the degree of unsaturation of a fat. Each double bond takes up two atoms of iodine, so unsaturation is quantified as the number of centigrams of iodine absorbed/gram of fat.
LCFA: The longer fatty acids (roughly 14 or more carbons) are often referred to in nutrition as LCFA (long-chain fatty acids).
Lipolysis: The activity of breaking ester bonds to cleave fatty acids from glycerol.
Melting point: The temperature at which solidified fat becomes liquid.
Nonesterified fatty acid: Same as free fatty acid; usually used in reference to fat metabolism.
Prilled fat: Fat that has been processed into small spherical shapes.
Protected fat: Fat treated to prevent biohydrogenation and increase rumen inertness.
Saturated fat: A fat comprised of glycerol and of mostly saturated fatty acids. The fatty acids are "saturated" with respect to hydrogen. A saturated fatty acid has no double bonds between carbon atoms. It is usually solid at room temperature.
Tallow: A mixture of animal fat with a titer above 40.
Titer: The temperature at which liquefied fat becomes solid. Titer may be as much as 3[degrees]C higher than melting point.
Triacylglycerol: A molecule of glycerol plus three fatty acids. Formerly described as triglyceride.
Unsaponifiable matter: Portion of fat source that will not react to form a soap (Figure 8-4). Unsaponifiable matter is used to assess fat quality and purity.
Unsaturated fat: A fat comprised of glycerol and of mostly unsaturated fatty acids. The fatty acids are "unsaturated" with respect to hydrogen. An unsaturated fatty acid has at least one double bond between its carbon atoms. It is usually liquid at room temperature.
[FIGURE 8-4 OMITTED]
The judgment of fat quality is made based on unsaponifiable matter, free fatty acid content of the fat, and degree of saturation in the fatty acids bonded to the glycerol. Fats of poor quality or fats that are kept under poor storage conditions will begin to fall apart. The process of falling apart in fats is described as turning rancid.
When fats turn rancid, the molecules of fat decompose, creating free fatty acids and new molecules. The presence of free fatty acids in the fat source indicates that the ester bonds in triacylglycerols have been broken. The level of free fatty acids in a feed fat gives an indication of the structural integrity of the triacylglycerols in the fat source. New molecules created as fats decompose will have reduced palatability and may even be toxic. As fats turn rancid, they will destroy fat soluble vitamins.
Pure fat (made of 100 percent triacylglycerol) will be 100 percent saponifiable (0 percent unsaponifiable matter). That is, the fatty acids linked to the glycerol should all react in potassium or sodium hydroxide solution to form soaps. The material in a fat sample that does not form a soap is not part of a triacylglycerol and would, therefore, depress fat purity and quality.
In ruminant nutrition, fat quality is assessed by fat hardness. A hard fat is one that is solid at animal body temperature. In solid form, the fat is less likely to interfere with microbial activity in the rumen. This characteristic of noninterference is described as rumen inertness. Fat hardness is measured using titer and iodine values (Table 8-1).
DESCRIBING FATTY ACIDS
Fats and the fatty acids that comprise them are described as saturated and unsaturated. These terms refer to the status of hydrogen in the fatty acid: a fatty acid is saturated or unsaturated with respect to the hydrogen. Examples of saturated fatty acids are palmitic acid and stearic acid. No more hydrogens can be added to either palmitic or stearic acid. Examples of unsaturated fatty acids are linolenic acid and linoleic acid. These fatty acids can accept additional hydrogens and in doing so, will become more saturated. Fats contain a mixture of fatty acids. When a fat is described as saturated or unsaturated, the description is in reference to the nature of the fatty acids in the fat.
There are three systems used to describe the fatty acids, which along with glycerol, make up fat. All systems use carbon length and double bond information about the fatty acid.
The first system involves counting the carbons and the double bonds starting from the carboxyl end (--COOH) and giving the location of the double bonds. The first number denotes the number of carbons. The second number, preceded by a colon, gives the number of double bonds. The third number, designated as delta (DELTA]), indicates the number of carbon atoms counting from the carboxyl terminal to the first carbon participating in each double bond. Using this method, linolenic acid would be 18:3 ([DELTA]9,12,15). Stearic acid would be 18:0 (Figures 8-5 and 8-6, respectively).
The second system involves counting the double bonds starting from the methyl or omega end (--CH3). The carbon length and number of double bonds is designated similarly to the first method described. The third number, designated as n-, indicates the number of carbon atoms counting from the methyl terminal to the first double bond. Using this system, linolenic acid would be identified as 18:3(n-3) and could be described as an omega-3 fatty acid. Stearic acid would be 18:0.
A third system for identifying fatty acids is to simply give the number of carbons and the number of double bonds. Linolenic acid, then, would be 18:3 and stearic acid would be 18:0.
As can be seen from Tables 8-2a and 8-2b, most fatty acids contain an even number of carbons. The most abundant are those with chains between 14 and 22 carbon atoms long.
[FIGURE 8-5 OMITTED]
[FIGURE 8-6 OMITTED]
THE REQUIREMENT FOR FATTY ACIDS
Unlike protein nutrition, which is mostly about meeting the requirement for essential amino acids, fat nutrition is not primarily about meeting the requirement for essential fatty acids. Fat nutrition is usually about meeting energy requirements. This is because most livestock diets made with usual feedstuffs will meet the animal's requirement for essential fatty acids. The fatty acids most often described as being essential for livestock are linoleic acid, 18:2 ([DELTA]9,12) or 18:2(n-6), arachidonic acid, 20:4 ([DELTA]5,8,11,14) or 20:4(n-6), and linolenic acid, 18:3 ([DELTA]9,12,15) or 18:3(n-3).
Animals are unable to synthesize n-6 or n-3 fatty acids de novo or to interconvert one series of fatty acids to another. However, most animals do possess the enzymes needed to convert one fatty acid to another fatty acid within the same series. Essential fatty acid requirements, therefore, may be expressed in terms of the two series rather than the individual fatty acids. Furthermore, the n-3 series is less likely to be deficient in usual diets and is not considered in balancing rations for most livestock. Fish and cats may be exceptions. Under at least some physiological conditions, for example, some types of fish may not be able to convert 18-carbon fatty acids to longer-chain, more unsaturated fatty acids of the same series (Owen, Adron, Middleton, & Cowey, 1975). In cats, there is apparently only limited ability to synthesize arachidonic acid from other n-6 fatty acids and so arachidonic acid may be a conditionally essential fatty acid for cats.
Linoleic acid is involved in maintenance of membrane function. Arachidonic acid is involved in the production of compounds called eicosanoids, which are needed for normal reproduction and platelet aggregation. A deficiency in the essential fatty acids may result in coarse hair coat, hair loss, skin lesions, or abnormalities in the reproductive system, adrenal glands, kidney, and liver (MacDonald, Anderson, Rogers, Buffington, & Morris, 1984).
FAT CONTENT OF FEED
The fat content of feedstuffs varies. The usual feedstuffs such as forages and grains contain 2 to 4 percent fat on a dry matter basis. On a dry matter basis, brewer's grains and distiller's grains contain about 10 percent fat and whole oilseeds such as soybeans and cottonseed contain about 20 percent fat. Rich sources of omega-6 fatty acids include plant oils and animal fats. Rich sources of omega-3 fatty acids include fish oils and flax.
Ingested fats and oils do not mix in the water moving through the digestive tube. For absorption to take place, the system uses emulsifiers to suspend small globules of fat in the water. The emulsifiers used are bile and phospholipids. Bile is made in the liver and secreted into the duodenum. Phospholipids look like triacylglycerols, except at least one fatty acid has been replaced by a compound containing phosphorus. Lecithin is an important type of phospholipid. Fish diets generally contain high levels of fat, and lecithin is often added to ensure that the dietary fat is emulsified adequately.
The small globules of fat are more efficiently attacked by the pancreas's fat-digesting lipase enzyme than is nonemulsified fat. During digestion, lipase breaks down triacylglycerols into free fatty acids and monoacylglycerols or glycerol. Glycerol and short-chain fatty acids are absorbed directly into the bloodstream. The LCFA and the monoacylglycerols are coated in bile salts. These emulsified fat packets are called micelles. Micelles are transported through the watery intestinal environment to the site of absorption at the intestinal wall. The LCFA and monoacylglycerols diffuse into the cells, leaving the rest of the micelle behind. Inside the intestinal cells, the monoacylglycerols and LCFA are then rebuilt into new triacylglycerols.
In intestinal cells, triacylglycerols are packaged into lipoproteins. Lipoproteins contain both lipid and protein.
Short-chain fatty acids and glycerol, as well as carbohydrates, proteins, minerals, water soluble vitamins, and water, will pass from the intestinal cell into the blood vessels of the mesentery during absorption. The mesenteric blood vessels carry absorbed materials to the portal vein and on to the liver. However, the lipoproteins made from monoacylglycerols and LCFAare passed from the intestinal cells into the lymphatic system during absorption in most species of domestic animals. In all livestock except poultry, absorbed lipoproteins move into the lymphatics, thereby bypassing the liver. The lymphatic system merges with the circulatory system at veins in the neck. At this location, the lipoproteins enter the blood. In poultry, absorbed fat is carried directly to the portal circulation and to the liver.
Outside the intestinal cell, the lipoproteins made from absorbed monoacylglycerols and LCFA are often called chylomicrons. Binding structures called apolipoproteins are embedded on the surface of a chylomicron. An enzyme called lipoprotein lipase is responsible for hydrolysis of circulating triacylglycerols in chylomicrons. This enzyme is located on the inside wall of blood vessels and it binds the apolipoprotein. The triacylglycerols inside the chylomicrons are then hydrolyzed into fatty acids and glycerol.
Cells in the vicinity of the fat hydrolysis absorb most of the fatty acids and glycerol. If the animal needs energy to meet its energy requirement, the cells may prepare the fatty acids for entrance into the tricarboxylic acid (TCA) cycle where they are oxidized for fuel. If the intake of energy is in excess of the animal's requirement, the cells may use the absorbed fatty acids to reform triacylglycerols and put them into storage. Adipose tissue is made of cells that specialize in fat storage. Concentrations of adipose tissue are called fat depots.
Absorption of monoacylglycerols and LCFA is summarized in Figure 8-7.
[FIGURE 8-7 OMITTED]
FAT STORAGE IN MONOGASTRICS AND RUMINANTS
In monogastrics, fatty acids are usually not changed from the point of ingestion to the point of storage in fat depots. This means that the same fatty acids in the feed fat are present in the micelles in the small intestine, the chylomicrons in the blood, and in the reformed triacylglycerols in fat depots. The triacylglycerols of fat depots in monogastrics, therefore, tend to have a similar fatty-acid composition to that of dietary fat. This explains the cause for "soft pork," a problem in the swine industry occurring as a result of feeding a diet rich in unsaturated fat (Averette Gatlin, See, Hansen, & Odle, 2003).
In ruminant animals, however, fatty acids are changed by the action of the microbes in the rumen. The microbes in the rumen obtain energy by oxidizing organic compounds, primarily carbohydrates. The oxidation of one substance requires the presence of an oxidizing agent, something that can be reduced. In most biological situations, oxygen serves as the ultimate oxidizing agent, accepting hydrogen to become water (H2O). However, there is little oxygen in the rumen. Microbes in the rumen must reduce all potential oxidizing agents including unsaturated fats. When an unsaturated fat is reduced, it becomes a more saturated fat. The triacylglycerols of fat depots in ruminants, therefore, tend to contain saturated fat regardless of the type of fat in the diet.
It should be noted, however, that for both monogastrics and ruminants, where energy intake is in excess of current needs, triacylglycerols may be manufactured from any absorbed compound that contains energy and stored in fat depots. The composition of this fat is not related to either dietary fat or microbial activity.
DIETARY FAT AND HUMAN HEALTH
In human nutrition, studies have suggested that diets rich in omega-3 fatty acids reduce blood cholesterol and triacylglycerol levels (Simopoulos, 2002). A major source of omega-3 fatty acids in human diets is fish oil.
Conjugated linoleic acid (CLA) has been shown to inhibit carcinogenesis in experimental animals (National Research Council, 1996). In most types of unsaturated fatty acids, the double bonds are separated by a single --C[H.sub.2]-- (methylene) group. For example, --CH = CH--C[H.sub.2]--CH = CH--. An exception exists in the conjugated fatty acids where there the carbons participating in adjacent double bonds are bonded (conjugated) to each other. For example, --CH = CH--CH = CH--. Dairy products are the major source of CLA in human diets (Bauman, Corl, Baumgard, & Griinari, 1998).
There is epidemiological evidence that trans fatty acids may increase the risk of heart disease (Willett, Stampfer, Manson, Colditz, Speizer, Rosner, Sampson, & Hennekens, 1993) in humans. In the diet of the U.S. adult, 80 to 90 percent of trans fatty acids are consumed via partially hydrogenated vegetable oils (Feldman, Kris-Etherton, Kritchevsky, & Lichtenstein, 1996). Margarine and vegetable shortening are food products made from partially hydrogenated vegetable oils. In manufacturing partially hydrogenated vegetable oils, hydrogen atoms are added to the unsaturated fatty acids in vegetable oil through an industrial hydrogenation (chemical reduction) process. As hydrogens are added, double bonds are eliminated and the fatty acid becomes more saturated with respect to hydrogen. This results in a more stable fatty acid and one with a higher melting point, which is the goal in making margarine and vegetable shortening from vegetable oils. Another change to the unsaturated fat takes place during the industrial hydrogenation process. Some of the unsaturated bonds are transformed to a trans configuration.
As vegetable oils, the hydrogens are usually both on the same side of the double bond. This is called the cis configuration (Figure 8-8). During the process of making margarine and vegetable shortening, some of the double bonds are changed so that the hydrogens are on opposite sides of the double bond. This is called the trans configuration (Figure 8-9). Trans fatty acids are unsaturated fatty acids that contain a trans double bond. In contrast to the more typical cis configuration, the trans double bond results in a more rigid, linear molecule with a higher melting point.
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[FIGURE 8-9 OMITTED]
Trans fatty acids also occur in nature. The fat in milk produced by cows fed diets deficient in forage has a higher content of trans fatty acids (Chapter 18). It is not clear if trans fatty acids that occur naturally have the same effect on heart health as those produced by hydrogenated vegetable oils.
In the feed industry, both fats and oils are generally referred to as fat. Most feedstuffs contain 2 to 4 percent fat. Though livestock do require essential fatty acids, this requirement is generally met with usual feedstuffs. The triacylglycerols that make up a molecule of fat are composed of a single glycerol molecule bonded to three fatty acids. There is great variety in the types of fatty acids that may be found in fat, and the fatty acid composition of fat determines its feeding value. Measurements of fat quality include titer and iodine value. Supplemental fat can improve a diet by increasing the energy density, reducing dustiness, enhancing palatability, and lubricating mixing and handling equipment. Most ingested fat is absorbed into the lymphatic system, thereby bypassing the liver.
1. Relate the following terms to one another in a single sentence: lipid, fat, oil, saturation, unsaturation.
2. Why is the fat in dairy products and meat products from beef, lamb, and goat highly saturated?
3. Explain why the iodine value of lard (pork fat) is more dependent on the type of dietary fat than is the iodine value of ruminant fat.
4. What is the relationship between rancidity and free fatty acid content of fat?
5. What is the relationship between the purity of a fat sample and its saponification value?
6. What is a triacylglycerol? What is a triglyceride?
7. A fat sample that has a high titer value would have a low iodine value. Explain why.
8. Describe the structure of a fatty acid identified as 18:2(n-6).
9. The requirement for fatty acids is sometimes described as a requirement for a series of fatty acids. One such series would include all those fatty acids in which the first carbon participating in a double bond is the 6th carbon counting from the methyl terminal (omega-6). Explain why the requirement for fatty acids is sometimes expressed as a requirement for a series of fatty acids.
10. Explain the difference between poultry and other domestic animals in how the LCFA derived from triacylglycerol is absorbed into the bloodstream.
Averette Gatlin, L., See, M. T., Hansen, J. A., & Odle, J. (2003). Hydrogenated dietary fat improves pork quality of pigs from two lean genotypes. Journal of Animal Science 81, 1989-1997.
Bauman, D. E., Corl, B. A., Baumgard, L. H., & Griinari, J. M. (1998, October 20-22). Trans fatty acids, conjugated linoleic acid and milk fat synthesis. In Proceedings of the Cornell nutrition conference for feed manufacturers (pp. 95-103). Rochester, NY.
Feldman, E. B., Kris-Etherton, P. M., Kritchevsky, D., & Lichtenstein, A. H. (1996). Position paper on trans fatty acids. Special Task Force Report. American Journal of Clinical Nutrition 63, 663-670.
MacDonald, M. L., Anderson, B. C., Rogers, Q. R., Buffington, C. A., & Morris, J. G. (1984). Essential fatty acid requirements of cats: Pathology of essential fatty acid deficiency. American Journal of Veterinary Research 45, 1310-1317.
National Research Council. (1996). Carcinogens and anticarcinogens in the human diet. Washington, DC: National Academy Press.
Owen, J. M., Adron, J. W., Middleton, C., & Cowey, C. B. (1975). Elongation and desaturation of dietary fatty acids in turbot (Scophthalmus maximus) and rainbow trout (Salmo gairdneri). Lipids 10, 528-531.
Pearle, G. G. (1995, October 24-26). The fats and protein research foundation. In Proceedings Cornell nutrition conference for feed manufacturers (pp. 1-2). Rochester, NY.
Simopoulos, A. P., (2002). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & Pharmacology (Uncorrected Proof).
Willett, W. C., Stampfer, M. J., Manson, J. E., Colditz, G. A., Speizer, F. E., Rosner, B. A., Sampson, L. A., & and Hennekens, C. H. (1993). Intake of trans fatty acids and risk of coronary heart disease among women. Lancet 341, 581-585.
Table 8-1 Fat quality as identified by titer and iodine value Fat source Titer Iodine Value Beef fat 42-47 50-54 Lard (pork fat) 38 65-75 Poultry fat 32 80-85 Vegetable oils Less than 0 105-128 Table 8-2a Fats and their component fatty acids (% of total fatty acids), part 1 Butyric Caproic Carbon Atoms: Double Bonds 4:0 6:0 Butter fat 3.6 2.2 Tallow (mutton) Tallow (beef) Lard Palm oil Chicken fat Peanut oil Cottonseed oil Rapeseed oil Canola oil Oat oil Corn oil Soybean oil Sunflower oil Safflower oil Cod liver oil Linseed oil Menhaden oil Caprylic Capric Carbon Atoms: Double Bonds 8:0 10:0 Butter fat 1.2 2.5 Tallow (mutton) 0.2 Tallow (beef) Lard 0.1 Palm oil Chicken fat Peanut oil Cottonseed oil Rapeseed oil Canola oil Oat oil Corn oil Soybean oil Sunflower oil Safflower oil Cod liver oil Linseed oil Menhaden oil Lauric Myristic Myristoleic Carbon Atoms: Double Bonds 12:0 14:0 14:1 Butter fat 2.9 10.8 0.8 Tallow (mutton) 0.3 5.2 0.3 Tallow (beef) 0.1 3.2 0.9 Lard 0.1 1.5 Palm oil 0.1 1.0 Chicken fat 0.1 0.8 0.2 Peanut oil 0.1 Cottonseed oil 0.1 0.7 Rapeseed oil 0.1 Canola oil 0.1 Oat oil 0.2 Corn oil 0.1 Soybean oil 0.1 Sunflower oil 0.1 Safflower oil 0.1 Cod liver oil 3.2 Linseed oil Menhaden oil 7.3 Pentadecanoic Palmitic Palmitoleic Carbon Atoms: Double Bonds 15:0 16:0 16:1 Butter fat 2.1 26.9 2.0 Tallow (mutton) 0.8 23.6 2.5 Tallow (beef) 0.5 24.3 3.7 Lard 0.1 26.0 3.3 Palm oil 44.4 0.2 Chicken fat 0.1 25.3 7.2 Peanut oil 11.1 0.2 Cottonseed oil 21.6 0.6 Rapeseed oil 3.8 0.3 Canola oil 4.1 0.3 Oat oil 17.1 0.5 Corn oil 10.9 0.2 Soybean oil 10.6 0.1 Sunflower oil 7.0 0.1 Safflower oil 6.8 0.1 Cod liver oil 13.5 9.8 Linseed oil 5.3 Menhaden oil 19.0 9.0 Margaric Margaroleic Stearic Carbon Atoms: Double Bonds 17:0 17:1 18:0 Butter fat 0.7 12.1 Tallow (mutton) 2.0 0.5 24.5 Tallow (beef) 1.5 0.8 18.6 Lard 0.4 0.2 13.5 Palm oil 0.1 4.1 Chicken fat 0.1 .01 6.5 Peanut oil 0.1 0.1 2.4 Cottonseed oil 0.1 0.1 2.6 Rapeseed oil 1.2 Canola oil 0.1 1.8 Oat oil 1.4 Corn oil 0.1 2.0 Soybean oil 0.1 4.0 Sunflower oil 0.1 4.5 Safflower oil 2.3 Cod liver oil Linseed oil 4.1 Menhaden oil 4.2 Table 8-2b Fats and their component fatty acids (% of total fatty acids), part 2 Oleic Linoleic Linolenic Carbon Atoms: 18:2 18:3 Double Bonds 18:1 n-6 n-3 Butter fat 28.5 3.2 0.4 Tallow (mutton) 33.3 4.0 1.3 Tallow (beef) 42.6 2.6 0.7 Lard 43.9 9.5 0.4 Palm oil 39.3 10.0 0.4 Chicken fat 37.7 20.6 0.8 Peanut oil 46.7 32.0 Cottonseed oil 18.6 54.4 0.7 Rapeseed oil 18.5 14.5 11.0 Canola oil 60.9 21.0 8.8 Oat oil 33.4 44.8 Corn oil 25.4 59.6 1.2 Soybean oil 23.2 53.7 7.6 Sunflower oil 18.7 67.5 0.8 Safflower oil 12.0 77.7 0.4 Cod liver oil 23.7 1.4 0.6 Linseed oil 20.2 12.7 53.3 Menhaden oil 13.2 1.3 0.3 Arachidic Gadoleic Arachidonic Carbon Atoms: 20:4 Double Bonds 20:0 20:1 n-6 Butter fat 0.1 Tallow (mutton) Tallow (beef) 0.2 0.3 Lard 0.2 0.7 Palm oil 0.3 Chicken fat 0.2 0.3 Peanut oil 1.3 1.6 Cottonseed oil 0.3 Rapeseed oil 0.7 6.6 Canola oil 0.7 1.0 Oat oil 0.2 2.4 Corn oil 0.4 Soybean oil 0.3 Sunflower oil 0.4 0.1 Safflower oil 0.3 0.1 Cod liver oil 7.4 1.6 Linseed oil Menhaden oil 2.0 0.2 Eicosa- pentaenoic Behenic Erucic Carbon Atoms: 20:5 Double Bonds n-3 22:0 22:1 Butter fat Tallow (mutton) Tallow (beef) Lard Palm oil 0.1 Chicken fat Peanut oil 2.9 Cottonseed oil 0.2 Rapeseed oil 0.5 41.1 Canola oil 0.3 0.7 Oat oil Corn oil 0.1 Soybean oil 0.3 Sunflower oil 0.7 Safflower oil 0.2 Cod liver oil 11.2 5.1 Linseed oil Menhaden oil 11.0 0.6 Docosa- Iodine hexaenoic Lignoceric Value Carbon Atoms: 22:6 Double Bonds n-3 24:0 -- Butter fat 25-42 Tallow (mutton) 35-46 Tallow (beef) 40-55 Lard 48-65 Palm oil 50-55 Chicken fat 74-80 Peanut oil 1.5 84-100 Cottonseed oil 98-118 Rapeseed oil 1.0 100-115 Canola oil 0.2 100-115 Oat oil 105-110 Corn oil 118-128 Soybean oil 123-139 Sunflower oil 125-140 Safflower oil 140-150 Cod liver oil 12.6 155-173 Linseed oil 169-192 Menhaden oil 9.1 170-200
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|Author:||Tisch, David A.|
|Publication:||Animal Feeds, Feeding and Nutrition, and Ration Evaluation|
|Date:||Jan 1, 2006|
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