Chapter 8 lipids animal nutrition

Where are the fatty acids in milk derived from in the body?(3)

a. Circulating triacylglycerol. b. Circulating nonesterified fatty acids originating from adipose tissue. c. De novo fatty acid synthesis in the mammary gland.

What are the 3 dietary essential fatty acids and which ones are most important?

linoleic, linolenic, and arachidonic acids. The first two are the most important and must be in the diets of all animals. a. These can't be synthesized by mammalian tissue. b. They are precursors of a number of highly unsaturated fatty acids produced in the body.

Adrenal corticoids function

(adrenal steroids}are involved in carbohydrate and protein metabolism, fluid and electrolyte balance, blood pressure regulation, stress resistance and more.

Estrogens and progesterone function

(female sex hormones) regulate estrus, reproductive cycles; influence protein and nucleic acid and lipid metabolism; and regulate normal bone metabolism.

Androgens function

(male sex hormones) are responsible for secondary sex characteristics, sperm maturity, activity of accessory glands of the genital tract, and promotion of N retention.

What is Ralgro and what is it used for?

(zeranol) is a pseudosterol used as a growth implant in beef cattle. (Note: It is not a sterol, but a pseudosterol.)

What are the important steroid hormones discussed?

- Many hormones are steroids synthesized from cholesterol by the adrenal cortex, gonads, corpora lutea, and placenta. 1. Adrenal corticoids 2. Estrogen and progesterone 3. Androgens

What happens to the Acetyl CoA made from beta oxidation

-entry into citric acid cycle -synthesis of long chain fatty acids -acetylation reactions -steroid synthesis -ketone body formation

How to increase HDL (high-density lipoproteins) levels

-exercise -eating beef

Plaque

-form along walls of arteries and cause thickening/hardening of arteries (arteriosclerosis) -cholesterol is main constituent -lead to blood clots and heart attack

Ketogenesis

-formation of ketones -continuous process -problems arise when present in excess -ketones are usually removed rapidly from blood by muscle and used to supply energy

Why is the body fat of a ruminant more saturated than a nonruminant

-many lipids are highly unsaturated plant fats, but highly reducing condition of the rumen hydrogenates them quickly to produce more saturated fatty acid

Do water soluble lipid molecules need to go through the micelle mechanism?

-no, fatty acids with less than 12 C are absorbed directly into the blood

Adipose Tissue

-specialized connective tissue that has a central role in energy metabolism for the whole animal -takes excess energy from blood and converts to triglyceride and stored there -function is under nervous and endocrine control -Have both nerve and blood supply

What affect does body fat have on percentage that is total body that is water

-the more fat, the less water

Where do the most lipids come from that ruminants consume

-triglycerides from seeds -galactolipids from leaves

What lowers cholesterol?

-vegetable fats // polyunsaturated fats

Define phospholipids, identify where they are found, and state what they do.

1. A heterogeneous group of compounds classified together because they have ester phosphorus present. 2. They occur in every living animal cell. Probably the major component of membranes (cell walls and internal cell bodies). They form stable complexes with lipids, carbohydrates and proteins to help with cell organization. 3. Other functions include Mitochondrial enzyme systems and lipid transport because of their emulsifying properties

What is the importance of fatty acids to nutrition?

1. Almost all naturally occurring lipids contain one or more fatty acids 2. All neutral fats and some other lipids also contain the trihydric sugar alcohol glycerol, which is more like the carbohydrates. 3. Most fatty acids found in nature are straight chained, monocarboxylic acids.

What is the average percent elemental composition of lipids?

1. Carbon 77% 2. Hydrogen 12% 3. Oxygen 11%

2.What are the four major functions of lipids in the animal body?

1. Energy supply 2. Source of essential fatty acids 3. Carrier for the absorption of fat-soluble vitamins from gut 4. Play an important role in cell membranes

What are five benefits to using fats as an energy source

1. Fats give more energy than carbohydrates. Greater energy density in a ration 2. Feeding fats can be especially useful for high producing animals. 3. Some forms of fat can be very cost effective feeds at times. This allows us to lower overall feed costs. 4. At the cellular level the oxidation of fatty acids to CO2 is a major means of metabolic energy production. 5. Fats are very digestible forms of feed energy.

Name the lipids of greatest importance in nutrition. (4 of them)

1. Fatty acids 2. Glycerol 3. Mono-, di-, and triglycerides 4. Phospholipids

Precursors for fatty acid biosynthesis

1. Glucose is the principal fatty acid precursor in monogastric animals. 2. Acetate and much smaller amounts of alpha-hydroxybutyrate are the principal fatty acid precursors in the ruminant mammary gland.

Name some sources of fat for livestock diets.

1. In plants we find fats primarily in seeds (oilseeds, soy beans, cotton seeds 18-25% lipid while grains, corn, wheat contains 2-4%) 2. Use of pure sources of fat such as tallow from beef and lard from hogs Protected fats such as megalac and energy booster bypass not digested in rumen. Increases energy density of ration

What controls gastric emptying?

A complex feedback mechanism controls gastric empytying. The presence of lipid in the duodenum controls the rate of emptying. This mechanism allows for time to get lipids digested and absorbed. Once the small intestine finishes with a load and the digested fats move on down the tract for absorption, another load is dumped from the stomach

What are lecithin?

A phospholipid that is a white, waxy substance that quickly oxidizes to brown when exposed to oxygen.

What is a terpene?

Are lipids that have isoprene-type structure

What is a sterol?

Are lipids with complex phenanthrene-type ring structures

Define lipids

Are organic compounds that are relatively insoluble in water but relatively soluble in organic solvents and serve important biochemical and physiological functions in plants and animal tissues

What is a derived lipid?

Are substances derived from the previous groups by hydrolysis They include fatty acids, glycerol, and other alcohols.

What is the name of the process used to degrade fatty acids?

Beta oxidation resulting in the removal of two carbons from the carboxyl end of the acid and is repeated to completely degrade fatty acid Makes acetyl COA which goes into citric acid cycle

How are bile acids and cholesterol linked?

Bile acids are cholesterol derivatives (and their function is to emulsify fats to make them water soluble and activate lipases)

What do fish have to do with the discussion around Omega 3 and Omega 6 fatty acids?

Depot fats or adipose tissues of fish contain several long-unsaturated fatty acids that are not present in significant amounts in other animal fats.

What type of emulsion is accomplished in the stomach?

In young, lecithin already emulsifies milk Most dietary fat is in the form of water-insoluble triglycerides (TGs) which are emulsified in the stomach and further emulsified in the small intestine. This is accomplished by the physical action caused by the peristaltic contractions and results in a coarse emulsion similar to what happens when we shake oil and water together

What is the significance of the position of the double bond for omega 3 and omega 6 fatty acids?

It is critical to biological activity

How is glycerol classified?

It is derived lipid

What is the importance of glycerol to nutrition?

It is the alcohol component of all triglycerides common in animal and plant tissues. It is also a component of phosphatides-lecithin, cephalin, and sphingomyelin

What do lecithins do?

Lecithin is commonly used in food processing to keep oils and water together. For instance, in mayonnaise its creamy and smooth because lecithin in egg yolk emulsifies the mix, acting as a bridge to hold them together

What % of lipids are taken up by ruminants?

Less than 5% because most whole plants are a max of 5% lipids

Is linoleic acid a precursor of arachidonic acid? If so then why is arachidonic acid essential?

Linoleic acid is the precursor of arachidonic acid, which is a precursor of prostaglandins. Since arachidonic acid can be synthesized from linoleic by some species, it is required only if linoleic is absent. The cat is a notable exception to this and requires a dietary source of arachidonic.

Name the dietary essential fatty acids. What is different about arachidionic?

Linolenic, linoleic, and arachidionic acid. Arachidonic acid is only essential if linoleic is missing because linoleic is the precursor to arachidonic acid.

3.What is the major enzyme of lipid digestion?

Lipase. There is both gastric and pancreatic lipase

In very low-fat rations fat-soluble vitamin deficiencies have been known to develop. Why do you think this is so?

Lipids are carriers for absorption of fat-soluble vitamins from gut. These vitamins are digested, absorbed, and transported along with fats. Animals on fat-free diets frequently develop fat-soluble vitamin deficiencies.

How does the small intestine of a ruminant treat fats?

Long-chain fatty acids form water-soluble salts, or soaps, and pass on for absorption in the small intestine. Once in the small intestine, they are treated generally the same by a ruminant as a monogastric treats them.

Define fats, oils, and waxes

Fats and oils are esters of fatty acids with glycerol. Waxes are esters of fatty acids with alcohols other than glycerol.

What comprises the largest fraction of lipids in most materials? Make some statement about the energy content of these lipids.

Fats and oils make up the largest fraction of lipids in most material. They have a high energy value (9.45 kcal/gram compared to 4.1 for carbohydrates).

What does increasing the fat content of a ration do for the energy density of the ration?

Fats are concentrated forms of energy. Because of the larger amount of energy per quantity of feed, fat-containing feeds allow us to get greater energy density in a ration.

Why doesn't the fat in milk separate immediately after the cow is milked?

Milk has lecithin in it naturally and this is white it takes several hours for the cream in milk to separate. The lecithin slows down the separation. Thus, milk is a temporary emulsion

What is the primary form of lipids in nature? Define it as well

Mono-, di-, and triglycerides. They are esters of glycerol and fatty acids with the composition being variable with the same or different fatty acids found in all three positions

What are the symptoms of EFA deficiency?

Monogastrics. Dull hair coat with possible hair loss. Scaly condition of skin and necrosis of the tail, failure to grow, and eventual death. Reproduction and lactation are also affected.

Where are most bile salts absorbed and where do they go?

Most are absorbed in the ileum and return to the liver to be resecreted because digestion needs more than the liver can produce

Are lipids polymers composed of one particular kind of building block?

No they are not polymers composed of one particular kind of building block like carbs or proteins

How does bile help lipase do its job?

Pancreatic lipase acts at the oil-water interface of the emulsion particle. Bile from the liver helps to orient the lipase with the triglycerides for hydrolysis. The bile salts also help in forming emulsion droplets. Also helps soulublize monoglycerides/ free fatty acids by forming micelles and increase surface area

What does lipid digestions require in the small intestine?

Pancreatic secretions and secretions from the liver

How does the micelle aid in absorption?

Shuttle the emulsion particle to the brush border of the jejunum where most absorption happens. This is helped by peristaltic movements of the gut

How do "statin" compounds work to lower cholesterol in humans?

Statin compounds are used to lower cholesterol levels in people with certain genetic makeups that result in defects such as type II hyperlipidemia. The compounds act by inhibiting HMG (hydroxymethylgluta) CoA reductase activity (significant enzyme in cholesterol synthesis) which results in the reduction of cholesterol biosynthesis.

Describe the metabolic problem for people with familial Type II hyperlipidemia. (See text pp. 107-108.)

The cause of familial type II hyperlipidemia is the result of a person's liver lacking cell surface receptors for low-density lipoproteins (LDL). This results in a defect that blocks the removal of these lipoproteins in blood. This defect also results in more LDL being produced then normal. Also, since there is a lack of cell surface receptors in the liver they cannot bind to very low density lipoproteins for degradation.

What are the most important factors in determining the physical and chemical properties of a triglyceride?

The chain length and the degree of unsaturation of the individual fatty acids making up the triglyceride

What is the biochemical function of EFA's?

The exact function of EFA's is unknown but it is widely distributed in phospholipids and cholesterol esters. The two probable vital areas for their function are: they are an integral part of the lipid-protein structure of cell membranes and they play an important part in the structure of several compounds called eicosanoids that play a role in the regulation of release of the hypothalamic and pituitary hormones.

Lymph system significance

The lymph system is present in most tissues of the body. Its function in absorption from the gut is a specialization of the overall system. Fluids also pass via osmotic pressure.

Mammary gland

The mammary gland of lactating animals is highly active in triacyglycerol synthesis and secretion into milk.

Describe the fate of triglycerides and galactolipids in the rumen.

The microbial population quickly breaks them down to FA, glycerol, and galactose which is catalyzed by microbially-produced lipases Glycerol is fermented to yield propionic acid Galactose is fermented to VFA's Produces more saturated fatty acids which is why there is more body fats for ruminants than non ruminants

What are some of the causes of fatty livers? (text p. 108)

-caused by accumulation of lipids in liver -fat is 30% wet weight of liver (usually 5%)

What does a phospholipid contain?

Also known as phosphatides, these lipids contain phosphoric acid and nitrogen (N).

What are the benefits of the CLA isomers to humans?

-CLA is an isomer of conjugated linoleic acid. -They protect against cancer, diabetes, atherogenesis, and obesity. They also modulate immune function and bone growth

Generate a list of the known functions of essential fatty acids in the body. You don't need to describe them -just list them.

-Play a role in lipid-protein structure of cell membranes. -Important part in the structure of eicosanoids. -Arachidonic acid helps the biosynthesis of Prostaglandins -Needed in sufficient amounts to prevent many pathological changes in the body

How is a chylomicron transported?

-The chylomicra are released from the mucosal cells and taken up by the lymph system. -In the lymph system each intestinal villus has at its core a central lacteal of the lymph system that takes up the chylomicron. Fluids pass into lymph by osmotic pressure. -The chylomicron travels with lymph fluid. It is dumped into the thoracic duct of the blood stream at the right atrium of the heart and travels to all parts of the body via blood.

What is a simple lipid?

-These are esters of fatty acids with various alcohols Fats, oils, and waxes are simple lipids

What is a compound lipid?

-They are esters of fatty acids but also contain groups in addition to fatty acids and alcohols -Phospholipids, glycolipids, and lipoproteins are the three major types.

How do triglycerides get transported in the blood?

-They combine with cholesterol, cholesterol esters, phospholipid, and protein to form a chylomicron. -Chylomicrons are water miscible and are one of the major in vivo transport forms of fat. -Chylomicrons are very much like micelles. The protein coat around them is especially important as a means of making them water soluble. Without the protein coat, fat is unable to leave the mucosa! cell.

What is the composition of a chylomicron?

-Triglyceride 80% -Cholesterol 2% -Phospholipid 7% -Cholesterol esters 9% -Protein 2%

Useful dietary supplement to prevent heart disease

-Vitamin E supplements -antioxident -prevents the oxidation of lipid material while it is circulating in the blood, which prevents creation of free radicals that cause damage to arteries and makes less susceptible to plaque

Prostaglandins

-biosynthesized from arachidonic acid -variety of metabolic effects: lower BP, stimulate smooth muscle contraction, inhibit norepinephrine-induced release of fatty acids, modulate immune function

What does microbial produced lipase do

-break down lipids consumed into fatty acids, glycerol (fermented to yield propionic acid), and galactose (fermented to VFAs)

What are the nutritional functions of lipids? Briefly describe each.

1. Lipids supply the body with concentrated forms of energy. This occurs as triglycerides are hydrolyzed to glycerol and fatty acids supply the body with concentrated forms of energy. Lipids are very digestible sources of energy with the true digestibility of fats exceeding 80% with some variability in utilization. 2. Lipids also serve as a source of essential fatty acids such as linoleic and linolenic acid which cannot be synthesized by animal tissue in sufficient amounts. The two most likely function of these essential fatty acids is to be an essential part of the lipid-protein structure of cell membranes and play a significant part in the structure of eicosanoids. Eicosanoids help regulate the release of hormones from the hypothalamus and pituitary gland. In addition, arachidonic acid is indirectly linked to essential fatty acids as they they require linoleic acid to be present in order to be synthesized. Arachidonic acid biosynthesizes prostaglandins which has many metabolic effects such as lowering blood pressure, stimulating muscle contraction, and many others. 3. Lipids act as a carrier of fat-soluble vitamins. When fats are digested and absorbed they form micelles. These structures shuttle fat-soluble vitamins to the border of the jejunum where they can be absorbed. Animals that have fat-free diets are more prone to developing fat-soluble vitamin deficiencies. 4. Lastly, lipids also act as integral part of cell membranes

Describe the difference in a saturated and an unsaturated fatty acid.

1. Saturated fatty acids are organic compounds that contain only single bonds between carbon atoms 2. Unsaturated fatty acids are organic compounds that contain one or more double bonds between their carbon atoms. 3. The double bonds of an unsaturated fatty acid are very reactive. This means that unsaturated fatty acids are less stable than saturated fatty acids.

Classify the lipids of importance in nutrition.

1. Simple lipids 2. Compound lipids 3. Derived lipids 4. Sterols 5. Terpenes

What are some variations in fatty acid structure?

1. The chain length varies from 2 carbons to 24 carbons. They also have an even number of carbons in the chain. The first carbon of the.chain is part of a carboxyl group. 2. There are naturally occurring variations such as: odd number of carbons, branched chains, hydroxy acids. These are less plentiful but are found in ruminant animals due to microbial synthesis and subsequent absorption by the animal. 3. The most common fatty acids have 16 or 18 carbons.

What 3 things do all lipids have in common

1. They are water insoluble but are soluble in organic solvents such as benzene, chloroform, and acetone 2. They are actually or potentially fatty acid esters 3. They are utilized by living organisms

Name the important tests for classifying physical characteristics of Lipids.

1. Triglycerides composed of a chain of 10 or more saturated fatty acids will be solid at room temperature. Any triglyceride less than 10 carbons will usually be liquid. 2. Triglycerides containing mostly unsaturated fatty acids are liquids at room temperature. Triglycerides whose composition is only long-chain saturated fatty acids are solids.

Briefly describe fatty acid biosynthesis.

A Fatty acids are synthesized in the microsome from Acetyl CoA. 1. The source of the Acetyl CoA can be carbohydrates, amino acids from degraded fats. 2. The fatty acid chain is assembled two carbons at a time. The carboxyl head of one fragment joins to the methyl tail of another a. The process· is repeated until the desired synthesis is accomplished. b. In actuality, the major fatty acid produced in this way from Acetyl CoA is palmitate. I) Other fatty acids are made by modifications of Palmitate. 2) The general procedures to generate the others are elongation, desaturation, and hydroxylation.

What type of state are lipids in the body in?

A very dynamic state. They are constantly being catabolized and anabolized

Classify fatty acids

Can be unsaturated or saturated. The carboxyl end of a fatty acid is hydrophilic. The carbon end is hydrophobic

What is the most common zoosterol? Sterol?

Cholesterol is the most abundant zoosterol (sterols of animal tissue) and is not found in plants Ergosterol is the most common sterol in plants and with sunlight makes vitamin D

Why isn't fat digested in the stomach?

Gastric lipase functions optimally at pH 5 for fats containing short chains of fatty acids and over pH 7 for long chain fats The pH of the stomach is much lower than this. Therefore not much fat digestion occurs in the stomach Gastric lipase is more important in young where pH is higher in the stomach and the fats in milk are already emulsified (remember lecithin)

Describe the fate of fats in the rumen. (Note: this is not a question about bypass fats.)

Generally, plants are low in percentage of fats (maximum of 5%) thus, adult ruminants take in less than 5% of lipids from their diets. The main sources of fats in ruminant diets are triglycerides from seeds and galactolipids from leaves. Once in the rumen, these lipids are broken down by the microbial population with the help of microbially-produced lipases. The lipase breaks triglycerides and galactolipids to fatty acids, glycerol, and galactose. Glycerol is fermented to yield propionic acid and galactose is fermented to volatile fatty acids. Once digested in the rumen, the short chain fatty acids can either be absorbed through the rumen wall, incorporated into the structure of the rumens microorganisms, or travel further down the digestive tract to the small intestine along with long-chain fatty acids.

0.Explain the significance of glycerol to the structure of a triglyceride.

Glycerol is significant to the structure of a triglyceride because triglycerides are esters of glycerol and fatty acids. Glycerol acts as the alcohol constituent and reacts with an organic acid (fatty acid) to form the ester which makes mono-, di-, and triglycerides. In addition, the position of the fatty acids on the glycerol is significant for absorption and utilization of fats.

Variability in lipids

The term "lipid is a collective term used for a wide variety of substances varying from simple, short-chain fatty acids to large, ver complex molecules They are heterogeneous compounds that are not always chemically related

What do lipids do when an animal has an energy deficit?

The triacylglycerols are hydrolyzed to glycerol and fatty acids and used as metabolic fuel.

Name the fish oils that are important to the discussion about omega 3 and omega 6 fatty acids.

The unique fatty acids in fish oils that set them apart from polyunsaturated fatty acids are: 1. Omega-3 fatty acid 2. Omega-6 fatty acid These fish oils consist of linolenic acid, eicosapentaenic acid, and docosahexaenoic acid

What is there a great deal of attention on in human diets and health?

There is currently a great deal of attention on trans-fatty acids in human diets and health. As of January i 2006 the amount of trans-fatty acids must be listed on food labels.

How do fish oils help people?

There is evidence that indicates a protective effect of fish oils against atherosclerosis in humans

What has been the subject of popular discussion for positive benefits to human health?

There is much scientific and popular discussion about the positive benefits to human health of Omega-3 fatty acids, Omega-6 fatty acids, and of congregated linoleic acid.

What does a lipoprotein contain?

These are lipids that have a protein moiety (part protein)

What does glycolipid contain?

These lipids contain carbohydrates and sometimes nitrogen

What is a micelle and what does it do?

They are sphere shaped water-soluble micelles with polar end on outside and insoluble end on the inside Take up free fatty acids which are dissolved in the interior of the molecule Increase surface area while decreasing diameter of particle Shuttle the emulsion particle to brush border of jejunum for absorption

What happens to short chain acids after digestion by microorganisms (3)

They can be... -absorbed through the rumen wall -incorporated into the structure of the microorganisms -passed down the tract with the feed to the small intestine

How lipids stored in the body

Triglycerides -all tissues but specifically adipose tissue -in very dynamic state

What happens to phospholipids during hydrolysis?

Upon hydrolysis they yield fatty acids, phosphoric acid, and usually glycerol and a nitrogenous base.