Exam 2 Flashcards
Describe, in details, lipid digestion and transport across the intestinal lining.
When lipids enter the rumen they will be broken down through lipolysis and hydrogenation lipods will be then broken down later in the SI by pancreatic lipase and bile salts into the micelles. These micelles will eventually be broken down to smaller particles known as chylomicrons. Chylomicrons will be dumped into the lymphatic system which will then be spread throughout the body by blood.
Describe how VFAs are produced and metabolized.
In ruminants VFAs are broken down into 3 main acids.
Acetic acid, propionic acid, and butyric acid are the end products through fermentation of starches and fibers. Pyruvate forms lactic acid, acetic acid, and fornic acid.
Lactic acid -> propionic acid (propionate)
Acetic acid -> butyric acid (butyrate)
Fornic acid -> waste
Acetic acid acid is the most abundant and used by mammary gland for milk production.
Propionic acid will go through TCA cycle to form glucose
Butyric acid will be used to make ketone bodies
Describe the major events regarding tissue origins and post- secretory metabolic transformation of lipoproteins within plasma compartment in ruminants
lipoproteins include chylomicrons, VLDL, IDL, LDL, and HDL CHYLOMICRONS
VLDL are used for energy because they are more available and low density.
VLDL -> IDL -> LDL
LDL is used for cholesterol transfer by LDL receptors
HDL is the most abundant and used primarily for cholesterol transport
Explain the events that take place in the body when a cow receives a dietary N source
When ruminants receive a N source it will be broke down in the rumen by rumen microbes. This will cause ammonia and CO2. Depending on the energy levels needed and the leftover N will determine how much ammonia will be leftover. Ammonia is converted to urea and brought to the Liver. Some urea will be brought back to rumen through saliva. The remaining will continue and be brought out the body through urine. Rumen Protected N sources will be broken down in Abomasum and SI. It will then be absorbed through the SI
VLDL is a major transporter of
VLDL is assembled in the liver from triglycerides, cholesterol, and apolipoproteins. VLDL transports endogenous products, whereas chylomicrons transport exogenous (dietary) products.
Very-low-density lipoprotein (VLDL) is the transporter of endogenous triglyceride (TG), and, ultimately, through its metabolic product,
What is the major function of apolipoprotein CII
Plays an important role in lipoprotein metabolism as an activator of lipoprotein lipase.
- Protein component of the lipoprotein.
- stabilizes the lipoprotein
- allows lipoproteins to be recognized by receptors on cell surfaces
- stimulates LPL to remove lipids from the lipoproteins
Major source(s) of glucose in the body include
- our body is maintained within a narrow range by the humoral control and a ‘lipostat’ system
- regulated by leptin from adipose tissues
- keeps our accumulated fat stores in check
- Any disturbance in this delicately poised homeostasis could be disastrous as it can lead to obesity and its associated metabolic manifestations
Which one of the following VFAs is most affected when there is low supply of succinate
Propionic acid production was increased by an acid adapted. These were lactate, fumarate, and succinate metabolites that are known to influence propionic acid synthesis.
Name three major functions of rumen microorganisms
Microbial protein production, degradation of feedstuff, transport
What are the major functions of butyric acid
Butyrate: mostly derived from acetate it is not a direct production in it a acetic acid put together. Important in ketones usage as energy. Metabolized by rumen epithelium to ketone bodies. In house energy source. Produces more energy than anything else. Important for ketogenesis. Most of it get absorbed through the rumen wall.
Briefly explain main characteristics of chylomicron compared to that of VLDL
Chylomicrons: These are large triglyceride rich particles made by the intestine, which are involved in the transport of dietary triglycerides and cholesterol to peripheral tissues and liver.
- size of chylomicrons varies depending on the amount of fat ingested
- A high fat meal: large chylomicron
Very low density lipoproteins (VLDL): produced by the liver and are triglyceride rich.
- Similar to chylomicrons the size: VLDL particles can vary depending on the quantity of triglyceride
- Triglyceride production in the liver is increased
- secreted VLDL particles are large: VLDL particles are smaller than chylomicrons
Methane production in the rumen is an important event because
Methane is an especially potent trace gas due to its global warming potential, 25 times that of carbon dioxide, and its 12-year atmospheric lifetime; it is the second largest anthropogenic greenhouse gas, behind carbon dioxide. Methaneis produced in the rumen as a product of normal fermentation of feedstuffs.
Which VFA has shown the lowest impact on feed intake
Absorption
Acetate: 70% rumen lumen, 20% ruminal wall, 50% portal vein
Propionate: 20% rumen lumen, 10% ruminal wall, 10% portal vein
Butyrate: 10% rumen lumen, 9% ruminal wall, 1% portal vein
Which one is the important precursor for synthesis of “butyric acid” in the ruminal carbohydrate degradation?
- originate from the catabolism of triglycerides
- from lactate fermentation by clostridia
- saturated short-chain fatty acid with a 4-carbon backbone
- commonly found in esterified form in animal fats and plant oils.
- produced by both chemical and biochemical routes.
- based on a biochemical method using anaerobic fermentation by Clostridial spp.
Which one of the following catalyzes the synthesis of acetyl Co-A
glycolysis -> pyruvate -> acetyl CoA -> citric acid cycle
The mitochondrial pyruvate dehydrogenase complex then catalyzes the oxidative decarboxylation of pyruvate to produce acetyl-CoA.
Another important use of acetate is as the major source of acetyl CoA for synthesis of lipids.
When ionophores are used, the results include.
- increase feed efficiency and body weight gain.
- used in a variety of cattle production scenarios.
- Growing cattle consume the majority of ionophores
- positive increase in growing cattle performance
- The response to ionophores is related to forage availability, forage quality, and concentration of ionophore used.
- Increases propionate and decreases acetate
What are the advantages and disadvantages of having an established protozoa population in the rumen
Advantages:
- Increase cellulose digestion
- slower fermentation of starch and sugars
- greater VFA production
- Increased transport on CLA and trans-11(18:1) fatty acid to duodenum and meat and milk.
- Degrade cellulose (epidinium),
- Degrade Starch (stored as amylopectin)
- Degrade soluble carbohydrates
Disadvantages:
- Increased rumen protein turn over (reduce efficiency of protein use)
- Increased CH4 production
- development of more virulent
- strains of pathogenic bacteria
Explain how each of the main VFAs is produced in the rumen [Hint: using a chart (schematic) may be useful (7 points)].
- produced in large amounts through ruminal fermentation
- provide greater than 70% of the ruminant’s energy supply
- Acetic, proprionic and butyric acids formed in the rumen: absorbed across the ruminal epithelium, from which they are carried by ruminal veins to the portal vein and hence through the liver.
1. Acetic acid is utilized minimally in the liver and is oxidized throughout most of the body to generate ATP.
2. Proprionic acid is almost completely removed from portal blood by the liver. Within the liver, proprionate serves as a major substrate for gluconeogenesis.
3. Butyric acid, most of which comes out of the rumen as the ketone beta-hydroxybutyric acid, is oxidized in many tissues for energy production.
What are VLDL?
Very low density lipoprotein
Delivers endogenous lipids from the LIVER to FAT and MUSCLE cells with the help of LPL, Becomes IDL
-Mostly triglycerides
What are IDL?
Intermediate Density Lipoprotein Transient Little nutritional impact TAGs are removed…becomes LDL Mostly Triglycerides
What are LDL
Low Density Lipoprotein
Delivers fat and cholesterol to cells (including arteries)
Mostly Cholesterol- neg. impact, Atherogenic; Increases risk for heart disease
What are HDL
- Removes cholesterol from cells and other lipoproteins
- Cholesterol is transported to the liver to be incorporated into bile
What is the tissue origins & post-secretory metabolic transformation of lipoproteins within plasma compartment in ruminants (HINT: use the chart)
Draw it out
What happens?
-Liver: CHL esters to FC to bile; TG & FC synthesis
-ADIPOSE TISSUE: FA to TG
-MUSCLE: FA oxidation
-MAMMARY GLAND: FA to TG
-PERIPHERAL TISSUE: CHL esters to FC to membrane components & steroid synthesis
What happens to the absorption of the peptides through brush border
- Absorption of peptides the primary mode of AA absorption and is more rapid than absorption of free AA
- PEPT1 transports di and tripeptides with ATPase
- Peptides are cleaved to AA in the enterocyte
What happens to absorption of Amino Acids and Brush Border
-AA must cross the brush border (apical) and basolateral (serosal) membranes before reaching the blood
-Most occurs in the duodenum and upper jejunum
-Types: facilitated, sodium dependent, paracellular
Brush Border
-Facilitated transport
Most are sodium dependent
Work in conjunction with an ATPase
Favor: Peptides with high hydrocarbon mass and net electrical charge
BCAA
Neutral
Essential
-Amino acids can compete for specific transporters
What are chylomicrons
- Lipids resynthesized in ER of enterocyte
- Contain TAG, cholesterol esters, phospholipids, and Vitamins A & E in core, with a surface of phospholipids, free cholesterol, and proteins
- Re-formed lipids derived from dietary sources (exogenous lipids)
- Exit enterocyte by exocytosis and transported in blood
What are factors of reduced feed intake
- Ration characteristics: Too much fiber; bulky
- Physiological state: Competition for space: late pregnancy, Sudden & significant increase in energy requirement: early lactation
- Environmental factors: Temperature, humidity, time
What is the difference between Physical fill and Chemostatic
Physical fill: distention of the gut tells the animal to stop eating
Chemostatic: absorbed nutrient in blood is monitored by receptors in brain - tells animal to stop eating
What is gastric distension
“hunger contractions of stomach”
- Physical capacity of the rumen
- Digestibility
- Passage rate
What is Glucostatic theory
Voluntary feed intake is controlled by glucose level
- Relatively constant (up after a meal; low right before a meal)
- Insulin concentrations
- ** UTILIZATION
What is Thermostatic theory
“eat to keep warm & quit to prevent hyperthermia”
In some experiments, cooling/warming the anterior hypothalamus
-> Change in feed intake
What happens when the body is thermostatic
Constant body temperature
- Food intake -> heat production
- Reduced intake -> body reserves
- Over-eating -> activation of heat loss mechanisms
What is Lipostatic theory
Adult: maintaining body fat content
What is Energostatic
Energy supply to specific tissues
Example: in sheep -> GH
-sensory factors: how palatable
Under low dietary CP condition, RDP is a major source of
RDP is the protein broken down in the rumen to microbial protein, and the protein that escapes the rumen is the RUP. In addition to protein, the source and types of carbohydrates are just as important. The balance between sugar, starch, and soluble fiber is essential for a healthy rumen
Under high dietary RDP condition, ruminal NH3 is
Ammonia in this form is known as ammonia gas or anhydrous (“without water”) ammonia. Ammonia NH3 is the foundation for all nitrogen (N) fertilizers. why is ammonia important? Nitrogen is an essential element and a much needed source of nutrition for growing plants
Ruminal degradation of cellulose results in production of
The degradation of cellulose occurs when the β-1,4 linkages are hydrolyzed by cellulase enzymes in Ruminococcus. A type of cellulase, endoglycosidase cleaves the disaccharide cellobiose from cellulose, and another type of enzyme, β-glucosidase hydrolyzes cellobiose and cellodextrins, producing glucose
Why the “gastric hunger” theory could not explain the feed intake regulation by itself
Hunger is a normal sensation that makes you want to eat. Your body tells your brain that your stomach is empty. This makes your stomach growl and gives you hunger pains. Hunger makes some people feel lightheaded or grouchy.
Briefly explain the function and importance of NPN in ruminant nutrition
Ruminants have the ability to metabolize non protein nitrogen like urea into protein. The non-protein nitrogen’s are a less expensive form of protein but must be used correctly. Urea is an example of a non-protein nitrogen (NPN) source. Many NPN compounds can supply nitrogen to the rumen microbes that then build microbial protein in the rumen using this nitrogen.
