Lipids

structure of a fatty acid

lipids contain one or more fatty acids and therefore fatty acids are considered the basic unit of lipids At one end of the molecule there is a carboxyl group (COOH). This is carbon 1 (C1) of the fatty acid. The carboxyl group gives the fatty acid its acidic properties. At the other end of the molecule is a methyl group (CH3). In between is the hydrocarbon chain of the fatty acid. Palmitic acid is an example of a fatty acid with 16 carbon atoms Linoleic acid, linolenic acid, and arachidonic acid are essential fatty acids.

triglyceride digestion in the rumen

major enzyme important in hydrolysis of lipids in the rumen is bacterial lipase. The source of the enzyme is the microorganisms. It hydrolyzes triglycerides completely forming glycerol and 3 fatty acids. It also hydrolyzes glycolipids completely to form glycerol, free fatty acids, and sugars.

ketone bodies

normally produced in liver and epithelial cells of the rumen wall during absorption of the VFA. Butyrate is converted to β-hydroxybutyrate which is a ketone body. A second ketone body, acetoacetate, is produced by liver. Both of these are used by cells to provide energy.

hydrophilic

Choline is polar and gives the molecule hydrophilic (water loving) characteristics. The hydrophilic characteristics promote the association of the molecule with water.

list common feed sources of the essential fatty acids

Common feedstuffs contain significant amounts of linoleic acid (w-6), particularly plant oils. Flax oil is an excellent plant source of alpha-linolenic acid. The longer chain ω-3 fatty acids are found in oils from coldwater fish. Salmon oil is a good example. Arachidonic acid is found in animals products only. Sources of arachidonic acid include fish oils, pork fat (lard), and poultry fat.

fatty liver

defined by triglyceride accumulation in liver. Triglyceride concentration of around 3% is normal. Greater than 10% triglyceride is abnormal.

d. emulsification, hydrolysis, micelle formation, chylomicron formation

hoose the order for these general steps of lipid digestion. Select one: a. emulsification, hydrolysis, chylomicron formation, micelle formation b. micelle formation, emulsification, chylomicron formation, hydrolysis c. hydrolysis, micelle formation, chylomicron formation, emulsification d. emulsification, hydrolysis, micelle formation, chylomicron formation

emulsification

in small intestine; first step in lipid digestion. This process breaks large fat globules into small droplets to increase solubility in the aqueous environment. Bile salts which are produced in the liver and phospholipids are amphipaths (or detergents) and have an important role in the emulsification process. As fats and oils enter the duodenum and mix with bile salts and phospholipids, emulsification results. Emulsified droplets have a polar portion composed of bile salts and phospholipids on the outer surface and an interior of triglyceride which is nonpolar.

acetic acid

(2 carbons) is the major VFA produced. It is primarily oxidized in the TCA cycle (citric acid cycle) providing a source of energy for cells of the body. Use of acetate for energy allows the animal to conserve glucose for other functions. Acetate is the precursor for synthesis of long chain fatty acids (C16 and C18) by adipose cells. Long chain fatty acids derived from acetate are used to form triglycerides for fat storage.

butyric acid

(4 carbons) is converted to β-hydroxybutyrate (a ketone body) during absorption. β-hydroxybutyrate is metabolized by cells and is a significant source of energy. Ketone bodies are important in metabolism of ruminants at all times including post-feeding. In many species, ketone bodies have a significant metabolic role under fasting conditions only.

biohydrogenation

(adding H to the double bonds) by the microorganisms to LCFA Because of the biohydrogenation process in the rumen, diet has little effect on the composition of fatty acids in body fat. Unsaturated fatty acids are hydrogenated to saturated fatty acids by rumen microorganisms.

fate of end products.

1. Glycerol and sugars, such as galactose, are fermented by the microorganisms forming volatile fatty acids (VFA). The VFA are passively absorbed from the rumen. 2. Long chain fatty acids (C16, C18) undergo the process of biohydrogenation (adding H to the double bonds) by the microorganisms. They may be completely hydrogenated forming saturated fatty acids or partially hydrogenated forming trans fatty acids. Long chain fatty acids are not soluble and are not absorbed from the rumen and pass to the small intestine with the digesta.

major functions of long chain fatty acids in the body

1. energy - Long chain fatty acids function to supply energy to cells and serve as a carrier for fat soluble vitamins. Some of the long chain fatty acids are essential fatty acids (EFA) which have specific roles. - energy: oxidized in the mitochondria of cells to produce energy. The process of fatty acid oxidation is termed β-oxidation. 2. storage and mobilization - Following a meal, nutrient supply exceeds demand and cells store energy for later use. Increased plasma insulin concentration following a meal promotes the uptake and storage of fatty acids in adipose tissue cells (adipocytes).Insulin increases the production of LPL by adipocytes. This will promote hydrolysis of triglycerides in chylomicrons, uptake by adipocytes of the fatty acids produced, and storage of these fatty acids in the form of triglyceride. An animal has almost a limitless ability to accumulate triglyceride.Triglyceride provides a source of energy for the body when needed. During fasting or periods of under-nutrition, insulin concentration decreases. As a result, the enzyme, hormone sensitive lipase increases in adipocytes. This enzyme hydrolyzes stored triglyceride to form glycerol and fatty acids. These components leave the cell. The fatty acids associate with albumin and travel to other body tissues where they are removed and used as a source of energy. 3. carrier for fat soluble vitamins - Fat soluble vitamins are essential nutrients that are required in very small amounts. Because of this, fat in the diet is important for efficient absorption of the fat soluble vitamins. Digestion of dietary fats and oils produces mixed micelles in the lumen of the small intestine. Fat soluble vitamins are incorporated into the core of mixed micelles to increase their solubility in the GI tract and promote absorption. Following absorption, fat soluble vitamins are incorporated into chylomicrons. This provides a mechanism to enhance their solubility as they enter the vascular system.

three things that are affected by the number of double bonds in a fatty acid.

1. reactivity (increases as number of double bonds increases. A more reactive fatty acid has increased susceptibility to autooxidation. As PUFAs oxidize, they produce breakdown products that have off odors and flavors. This process leads to formation of rancid fatty acids) and oxidation (increases at greater temperatures. In feed, this process will increase if storage is outdoors in the summer because of the heat. Antioxidants are added to feeds to decrease oxidation. Some of the antioxidants added are synthetic such as BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), and ethoxyquin. Vitamin E is a naturally occurring antioxidant) 2. physical structure - As the number of double bonds increases, the melting point decreases. Unsaturated fatty acids are usually liquids at room temperature. Saturated fatty acids with more than 10 carbon atoms are solids at room temperature. Vegetable oils contain many PUFAs and are liquids. Fats, such as beef tallow or lard from pigs, have more saturated fatty acids and are solids at room temperature. 3. iodine value - higher value indicates a more unsaturated fatty acid.

structural classification with emphasis on triglycerides

1. simple lipids - esters of alcohol and fatty acids. There are two subcategories to the simple lipids. A). Neutral fats or oils are esters of the alcohol, glycerol, and fatty acids. *** Triglycerides are the major example and the most common form of lipids in feeds. The second subcategory is the B). waxes. Waxes are esters of an alcohol other than glycerol and fatty acids. Waxes have little nutritional value but serve a protective function in plants and animals. Two examples are lanolin from wool and the waxes on leaves of plants. 2. compound lipids - Compound lipids contain groups in addition to alcohol + fatty acids. Two examples are A). phospholipids [property of phospholipids is that they have both a polar and nonpolar portion to their structure. ] and B). glycolipids [Glycolipids are composed of glycerol, two fatty acids and a sugar; galactolipid. These are commonly found in grasses.]. 3. derived lipids - Derived lipids are derived from simple of compound lipids by hydrolysis. They include fatty acids, glycerol, and other alcohols. 4. Steroids - synthesized in the body and have an important role in digestion or metabolism. They have a common basic ring structure. They are amphipathic molecules that have an important role in fat digestion. Steroid hormones such as glucocorticoids, estrogens, and androgens have many important roles in the body and are also in this category.

rancidity

A more reactive fatty acid has increased susceptibility to autooxidation. As PUFAs oxidize, they produce breakdown products that have off odors and flavors. This process leads to formation of * rancid fatty acids.

d. They must be treated by heat to remove the trypsin inhibitors.

All of the following are accurate in describing fats and oils in feed except: Select one: a. They increase caloric density b. They decrease dustiness. c. They enhance palatability. d. They must be treated by heat to remove the trypsin inhibitors. e. The fat content in the diet of ruminants must not be greater than 8-9%

a. Unsaturated fatty acids are usually solids at room temperature

All of the following statements accurately describe unsaturated fatty acids except: Select one: a. Unsaturated fatty acids are usually solids at room temperature b. They have an increased susceptibility to autoxidation c. They form cis and trans isomers. d. They contain a carboxyl group that gives them their acidic characteristic.

b. emulsification

Bile salts play a major role in this process. Select one: a. esterification b. emulsification c. coprophagy d. ruminal acidosis

give practical examples of addition of fat to diets of specific animals

Dairy cow - 4 to 6% added fat This is usually included in early lactation to increase energy without adding more grain. It also gives the flexibility to add energy and maintain fiber levels in the diet. The fiber is needed for proper rumen function. Whole cottonseed is a feedstuff that is often used. Megalac, an escape fat source, is another example. Horse - 8 to 10% added Fat may be added to the diet of high performance horses. The fatty acids provide energy for muscle and spare glucose because a greater proportion of the energy used by muscle is generated from fat. Vegetable oils, such as corn oil, linseed oil, or canola oil are often added. Pig - 3 to 7% added Fat may be added to the diet of lactating sows to increase energy density. A variety of fats or oils may be added including corn oil, soybean oil, poultry fat, lard, or tallow. Working dogs - 20% added The extreme energy demands of working dogs require added dietary fat. Usually animal sources are added such as poultry fat, lard, or tallow. For other dogs, that do not have these extreme energy requirements, the diet contains lesser amounts of added fat. In addition to providing energy a small amount of fat or oil increases palatability and decreases dustiness of the diet.

occurrence, causes, and prevention or treatment of diabetes mellitus.

Diabetes occurs in dogs (1 in 500) and in cats (1 in 400). It occurs most frequently in adults and is often associated with obesity. It occurs infrequently in cattle, pigs, or sheep. Insulin resistance occurs in horses. One cause is an absolute lack of insulin (termed Type I diabetes) due to inadequate production by the pancreas. A second cause is a relative lack of insulin (termed Type II diabetes). In the case of Type II, insulin is present but the tissues don't respond as well to the hormone. There is a decreased sensitivity to the hormone. Insulin responsive tissues are muscle, adipose, and liver. Insulin resistance in horses is similar to Type II diabetes. Treatment will depend on the cause. In some cases daily insulin injections are required to regulate blood glucose concentration. Medications to improve tissue sensitivity to insulin can be used also. In addition to drugs, exercise and diet have a role in treatment. Exercise increases uptake of glucose by muscle cells independent of insulin. Because of the large muscle mass in the body, increasing glucose uptake by the cells will contribute to decreasing hyperglycemia. The objectives for dietary treatment are to minimize highs and lows in blood glucose concentration and to promote weight loss if the animal is overweight. There are two approaches to accomplish these objectives: changing meal frequency and changing composition of the diet. Increasing meal frequency and consuming smaller meals will help. This approach will result in a smaller amount of glucose being absorbed following a meal and therefore less of an increase in blood glucose concentration.

occurrence, causes, and prevention or treatment of fatty liver

Fatty liver also occurs in laying hens on a high carbohydrate diet. In this case the animal is fed excess energy. Lipogenesis takes place in the liver of birds. Dietary glucose is absorbed and converted to long chain fatty acids in liver. The triglycerides remain in the liver until they are transported out of the liver for storage in adipose tissue. The liver may accumulate 30-50% triglyceride. The result is an enlarged liver that may hemorrhage and rupture. The syndrome leads to decreased egg production and increased mortality. Fatty liver occurs in association with ketosis or other conditions of undernutrition. The common factor in these cases is increased lipolysis and triglyceride mobilization from adipose tissue due to undernutrition. The fatty acids are taken up by the liver. Some of the fatty acids are combined with glycerol to form triglycerides. The triglycerides remain in the liver until they are transported out to provide energy for body tissues. Note that metabolically these two situations for development of fatty liver are the opposite of one another. The cause of fatty liver is that the normal mechanisms to transport triglyceride out of liver are not adequate. A lipoprotein called a very low density lipoproteins (VLDL) must be formed in the liver to transport fat out of liver and deliver it to body tissues. This is a lipid-protein complex similar to a chylomicron that has triglyceride at its core. The liver does not produce these in adequate amounts to prevent build up of triglyceride. For laying hens, the treatment is to alter the composition of the diet to decrease the amount of energy consumed by the hen. Removal of some corn from the diet and replacing it with feedstuffs having a lower energy value will produce a diet with lower metabolizable energy. For fatty liver occurring in conjunction with ketosis or other conditions of negative energy balance, the primary condition of energy intake must be addressed.

esterification

In the case of a triglyceride, a condensation reaction takes place as each fatty acid forms an ester bond with glycerol.

EFAs

Linoleic acid has 18 carbon atoms and 2 double bonds. Note that the double bonds are between carbons 9 and 10 and between carbons 12 and 13, with the carboxyl carbon numbered as carbon 1. The body cannot make the double bond between carbons 12 and 13 and therefore the fatty acid is essential. Linoleic acid is an omega-6 fatty acid. The first double bond from the methyl end begins on carbon 6. The second EFA is alpha linolenic acid. This fatty acid has 3 double bonds. There is more than one fatty acid isomer with 18 carbon atoms and 3 double bonds. Therefore, alpha is a very important part of the name to indicate the specific fatty acid. Alpha linolenic acid is an omega-3 fatty acid. The first double bond from the methyl end begins on carbon 3. The third EFA is arachidonic acid. This fatty acid has 4 double bonds and 20 carbon atoms in the chain. It is also an omega-6 fatty acid.

LCFA

Long chain fatty acids are insoluble in water. The diet is the major source of LCFA. They are absorbed from micelles in the small intestine and incorporated into chylomicrons for transport to body tissues. They have a gross energy value of 9.45 kcal/g. Long chain fatty acids are insoluble in water. The diet is the major source. They are absorbed from micelles in the small intestine and incorporated into chylomicrons for transport to body tissues. They have a gross energy value of 9.45 kcal/g. Dietary fats and oils are often added to the diet to increase energy density. Some LCFA are essential in the diet. We will describe the function of all fatty acids and then distinguish the functions of essential fatty acids.

amphipath

Molecules that have both a hydrophilic portion and a hydrophobic portion - phospholipids; They have an important role in digestion of lipids and function as detergents.

b. arachidonic acid

Most animals have 2 essential fatty acids, but cats have 3 essential fatty acids. Which of the following is the ADDITIONAL essential fatty acid for the cat? Select one: a. taurine b. arachidonic acid c. linoleic acid d. alpha linolenic acid

general types of fatty acids in lipids of fats or oils

Most fatty acids in nature are cis isomers. Unsaturated fatty acids are usually liquids at room temperature. Saturated fatty acids with more than 10 carbon atoms are solids at room temperature. Vegetable *oils contain many PUFAs and are liquids. *Fats, such as beef tallow or lard from pigs, have more saturated fatty acids and are solids at room temperature.

Pancreatic lipase

Pancreatic lipase hydrolyzes fatty acids in position 1 and 3 of the triglyceride to produce a 2-monoglyceride and free fatty acids. Fatty acids with 12 carbon atoms or less are relatively soluble in water and are passively absorbed. Fatty acids with greater than 12 carbon atoms are not water soluble. These will be incorporated into mixed micelles.

occurrence, causes, and prevention or treatment of ketosis

Problems associated with elevated ketone bodies in blood include metabolic acidosis. In addition, as the concentration of ketone bodies in blood increases, they spill over to the urine. Water follows which can lead to dehydration. Acetoacetate is toxic to the central nervous system. Ketosis occurs in high producing dairy cows in early lactation. Usually this is in the first 3-8 wks of lactation. Incidence is 2-15% of cows. The situation leading to ketosis is increased milk production without an adequate increase in feed intake. Approximately 1% of cases die and 5% are culled. Most cows usually recover. Pregnant ewes and does with 2 or more fetuses, are also susceptible to ketosis during the last month of gestation. They often decrease feed intake due to pressure of fetus on rumen. Other general situations where ketosis may occur in any animal are starvation, consuming a high fat, low carbohydrate diet, or as a consequence of diabetes. The causes of ketosis are hypoglycemia and negative energy balance. Prevention of ketosis is the best treatment. Feeding glucose precursors, such as propylene glycol, provides substrate the liver can use to synthesize glucose. This can be incorporated into a grain mix. In the short term, an intravenous glucose solution can be given to provide an immediate source of glucose for the animal. This is not a good long term treatment because of the quantity of glucose that is needed. Injection of glucocorticoid hormones can be used to promote gluconeogenesis. The goal of treatment is to increase glucose concentration and decrease lipid mobilization.

hard fat

Ruminants have "hard fat" in body tissues due to a larger portion of saturated fatty acids. The hard fat refers to the fact that the fat is a solid at room temperature and has a relatively high melting point.

b. most are produced by microbes

Select from the following statements the INCORRECT description of long chain fatty acids. Select one: a. relatively insoluble in water b. most are produced by microbes c. packaged in chylomicrons to be transported d. energy per gram is 9.45 kcal/g

b. The primary source of VFAs is from feed, and the primary source of LCFAs is from microbes.

Select the INCORRECT comparison of VFAs and LCFAs. Select one: a. VFAs are very soluble in water, and LCFAs have a low solubility in water. b. The primary source of VFAs is from feed, and the primary source of LCFAs is from microbes. c. VFAs produce energy similar to carbohydrates, and LCFAs produce 9.45 kcal/g. d. They are transported by different mechanisms through the body.

hydrophobic

The long chain fatty acids are nonpolar and give the molecule hydrophobic (water fearing) characteristics. Hydrophobic molecules do not associate with water.

functions of the EFA.

The EFA are important to the proper functioning of biological membranes. They are also precursors to a group of lipid families termed eicosanoids. 1. biological membranes - structure is a phospholipid bilayer with proteins on both surfaces as well as spanning through the membrane. The fatty acids are part of the structure of the phospholipids in the membrane. Because the EFA are polyunsaturated fatty acids they contribute to a more open structure of the phospholipids and function to give the membrane fluidity. The function of the biological membrane is to regulate the cellular environment. Membrane fluidity is important for transport of nutrients through the membrane. It is also important for cell regulation. Hormone receptors are located on the outer surface of the membrane and have mobility to function. 2. eicosanoids - precursors to a group of lipid families termed eicosanoids. There are four families of eicosanoids. For each family, there is an omega-3 series of compounds and an omega-6 series of compounds. The parent compound for each series is the respective 20C fatty acid as shown in Table 3. The parent eicosanoid for the omega-6 (ω-6) series is arachidonic acid and for the omega-3 (ω-3) series is eicosapentaenoic acid (EPA). The four families are: prostaglandins, thromboxanes, leukotrienes, and prostacyclins. Eicosanoids are lipids with hormone-like action in the body. They act as signaling molecules. They are part of the complex control of many body systems. They affect the nervous system, immune system, reproductive system, blood clotting, gastrointestinal function, and many more processes.

a. acetic acid

The VFA that makes the most significant contribution to oxidation in the body is __________. Select one: a. acetic acid b. lactic acid c. butyric acid d. propionic acid

d. 10

The body cannot make fatty acids with double bonds past which carbon (counting from the carboxyl end of the molecule)? Select one: a. 2 b. 4 c. 7 d. 10

omega-6 fatty acids

The first double bond from the methyl end begins on carbon 6.

b. acetic acid, propionic acid, and butyric acid

The main volatile fatty acids produced by microbes in the GI tract are: Select one: a. linoleic acid and alpha linolenic acid b. acetic acid, propionic acid, and butyric acid c. linoleic acid, alpha linolenic acid, and arachidonic acid d. acetic acid and butyric acid

eicosanoids

They act as signaling molecules. They are part of the complex control of many body systems. They affect the nervous system, immune system, reproductive system, blood clotting, gastrointestinal function, and many more processes.

trans fatty acids

Trans isomers are formed when each hydrogen atom is on the opposite side of the double bond. Trans isomers are produced by microorganisms in the rumen and may be found in ruminant products. Trans isomers are produced also during industrial processing of PUFA to form saturated fatty acids. Some of the partially hydrogenated fatty acids from this process have the trans isomer form.

lipoprotein

Triglycerides are packaged into a lipoprotein transport to body tissues ex: chylomicron

c. a detergent in the GI tract that helps to emulsify fat

What is an amphipath? Select one: a. an inactive precursor important in digestion of protein b. an enzyme important in digestion of lipid c. a detergent in the GI tract that helps to emulsify fat d. a nutrient that is passively absorbed by the rumen

a. a member of a group of lipid families

What is an eicosanoid? Select one: a. a member of a group of lipid families b. an essential fatty acid needed by most animals c. a protein that is important in promoting lipogenesis d. what remains of the amino acid after deamination

b. propionic acid

Which of the following fatty acids is used in the formation of glucose in the ruminant? Select one: a. butyric acid b. propionic acid c. arachidonic acid d. linoleic acid

c. linolenic

Which of the following is an essential fatty acid? Select one: a. butyric b. palmitoleic c. linolenic d. caproic

hypoglycemia

abnormally low blood sugar usually resulting from excessive insulin or a poor diet

diabetes mellitus

absolute or relative lack of insulin. As a result, the body is unable to maintain glucose homeostasis An associated problem with diabetes is hyperglycemia. This can lead to glucose in the urine if not controlled. Glucose in urine can lead to osmotic dieresis in that water will follow glucose into the urine. This can then result in dehydration. Ketosis is also associated with diabetes due to intracellular glucose deficiency even though glucose may be elevated in plasma. As a result, lipolysis increases to mobilize stored triglycerides to provide energy for body cells. The concentration of fatty acids increases and there is a greater production of ketone bodies by the liver.

negative energy balance

decreased feed intake

major function of each VFA in the body.

acetic - energy through TCA cycle propionic - gluconeogenesis butyric - energy (keytone bodies) VFA have the same potential uses in metabolism of simple-stomached animals as in ruminants. They make a significant contribution to energy needs of horses and other herbivores; they make a lesser contribution in omnivores and carnivores

cis fatty acid

based on the orientation of the hydrogen atoms around the double bond. Cis isomers are formed when the hydrogen atoms are on the same side of the double bond. Most fatty acids in nature are cis isomers.

post-gastric fermentation

cecum/colon VFA are derived from post-gastric fermentation (cecum/colon). The cell wall of forages in the diet are digested by microbial enzymes located here. Other dietary components that are not hydrolyzed in the small intestine may also be hydrolyzed by microbial enzymes. The products of hydrolysis are metabolized by the microorganisms. The VFA are an end product of microbial metabolism.

lipoprotein lipase

enzyme that hydrolyzes triglycerides in lipoproteins is Lipoprotein lipase (LPL). This enzyme is located on the surface of endothelial cells that line capillary beds in body tissues. Hydrolysis of triglycerides produces glycerol + fatty acids. The fatty acids are then taken up by cells and used for several different functions. Glycerol stays in circulation until it is removed by the liver.

saturated fatty acid

has two hydrogen atoms bonded to each of the carbon atoms in the hydrocarbon chain. Palmitic acid is an example of a saturated fatty acid.

polyunsaturated fatty acid (PUFA)

has two or more double bonds monounsaturated fatty acid has one double bond A double bond is formed when two hydrogen atoms are removed from the hydrocarbon chain. Linoleic acid is an example of a polyunsaturated fatty

rumen-protected fat

not metabolized by the microorganisms. It will be digested in the small intestine. fats that may be included in the diets of ruminants that are formulated to prevent hydrolysis of dietary fat by rumen microbes. These are often added to diets of lactating cows in early lactation to increase energy density of the diet without having a negative impact on rumen fermentation.

propionic acid

odd number of carbon atoms (3 carbons) which is significant to its function. The major use of propionate is synthesis of glucose in the process of gluconeogenesis. This is a continual process for the ruminant because it never absorbs enough dietary glucose to meet its metabolic needs.

fat quality

one consideration when choosing a source of fat to add to the diet. This is more of a problem with PUFA than saturated fatty acids. The concern is the potential for oxidation leading to rancidity. When a source of unsaturated fat is added to the diet, antioxidants are added also. Examples of antioxidants include vitamin E, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and ethoxyquin.

micelles

organized droplets containing lipid digestion products including 2-monoglycerides and free fatty acids and bile salts. They are arranged with the polar portion of the molecules toward the exterior of the droplet and the nonpolar portion toward the interior. Digestion products are absorbed from the mixed micelle into the intestinal cell.

lipolytic

pancreatic lipase. This enzyme promotes lipolysis in the lumen of the small intestine. hydrolyzes triglycerides to free fatty acids and monoglycerides.

pre-gastric fermentation

rumen

VFA

short chain fatty acids that are soluble in water, primarily derived from microbial metabolism in the GI tract, absorbed passively where they are produced, and have a gross energy value closer to carbohydrates than to lipids. The importance of VFA in metabolism varies across species. They are more significant and produced in greater quantities in herbivores compared to omnivores or carnivores. Within the herbivores, there is greater production in ruminants than in animals with post-gastric fermentation only. derived from pre-gastric (rumen) and post-gastric (cecum/colon) fermentation. They are very important in ruminant metabolism.

ketosis

situation of elevated ketone bodies in blood. This condition is most common in ruminants.

omega-3 fatty acids

the first double bond from the methyl end begins on carbon 3.

iodine value

the grams of iodine that react with 100 g of fat. Because the iodine reacts at the double bonds, it is a measure of the degree of unsaturation or number of double bonds. A higher value indicates a more unsaturated fatty acid.

chemical and specific enzymatic components of digestion of triglycerides

the pancreas secreted pancreatic lipase. This enzyme promotes lipolysis in the lumen of the small intestine. The liver secretes bile acid. The bile acid results in solubilization of lipid components in micelles. Fatty acids are absorbed in the jejunum. They will be delivered to body tissues in the lymphatic system. 1. mouth - Salivary lipase - little contribution 2. stomach - Gastric lipase is secreted by the chief cells of the stomach. It is active at an acidic pH. It too makes a minor contribution to lipid digestion. 3. A). emulsification (As fats and oils enter the duodenum and mix with bile salts and phospholipids, emulsification results); **Pancreatic lipase is secreted by the pancreas into the duodenum. This is the major enzyme of lipid digestion. It hydrolyzes triglycerides to free fatty acids and monoglycerides. *Colipase is also secreted by the pancreas. It is required for full activity of pancreatic lipase. B). miscelles C). chylomicron (Once inside the intestinal cell, triglycerides are formed in the smooth endoplasmic reticulum of the cell by esterification of the 2-monoglycerides and fatty acids. Triglycerides are packaged into a lipoprotein called a chylomicron for transport to body tissues) D). Chylomicrons enter the lymphatic system and eventually reach the vascular system to transport lipids to body tissues.

hydrogenation

the process of converting unsaturated fats to saturated fats by adding hydrogen

essential fatty acids (EFA) - characteristics

these are fatty acids that have a structure important to body function that the body cannot make. The key reason they are essential relates to the location of the double bonds in the fatty acids. Numbering the hydrocarbon chain beginning at the carboxyl end, the body cannot insert double bonds between carbon 10 and the methyl end of the fatty acid chain. The body can insert a double bond at carbon 9. The EFA provide both omega-3 and omega-6 fatty acids.

***triglyceride

three fatty acids esterified to the glycerol molecule. Depending on the type of fatty acid, triglycerides may be solids (fats) or liquids (oils) at room temperature. Triglycerides that are composed primarily of saturated fatty acids will have greater intramolecular forces associated with the fatty acid chains, have a higher melting point, and exist as solids at room temperature. In contrast, triglycerides that have a greater proportion of unsaturated fatty acids (cis isomer) have fewer interactions between the fatty acid chains, have a lower melting point, and exist as liquids at room temperature. It is the orientation of the hydrogen atoms around the cis double bond that contributes to the more open structure of the triglyceride. Formation of a triglyceride is an example of a condensation reaction in which water is removed from the molecule and is a product of the reaction In the case of a triglyceride, a condensation reaction takes place as each fatty acid forms an ester bond with glycerol. This is termed esterification. Breaking down a triglyceride is an example of an hydrolysis reaction. Water is a substrate in the reaction. It is termed de-esterification.