Carbohydrates and Carbohydrate Flashcards
are carbs essential as an energy source
- no evidence suggests they require carbs but because their diet is mostly plants its over 50% of their diet
what is the role of carbs in plants
- energy transformations ; for tissue synthesis ( glucose is a major building block, synthesize lipids and amino acids)
- energy reserve ( starch is the most important in plants )
- structural support for living plants ( cellulose and hemicellulose (carbs) lignin (non carb)
what % of carbs is found in the animal body
<1% very little found in animal body
- in the form of glycogen (stored in liver and muscles) and glucose
how do you classify monosaccharides?
which are most important on a nutrient bases
1 sugar unit
- glucose
- fructose (to make sucrose )
- galactose (lactose building block)
how do you classify disaccharides and which are most important ?
2 sugar units
- lactose = milk sugar (made by glucose and galactose )
- sucrose ( made by glucose and fructose)
- maltose = aids in carb digestion in the small intestine (glucose and fructose)
what classifies oligosaccharides
3-10 sugar
how do you classify polysaccharides and which are the most important
- over 10 sugar units
- starch (glucose)
- glycogen (glucose)
- dietary fiber (cellulose hemicellulose)
how can monosaccharides be classified
- number of c atoms
- pentoses and hexoses being the most important
what is a chiral carbon and how is it important to nutrition
chiral carbons are asymmetrical enzymes with D and L forms on the 5 C
- OH on right = D
OH on left = L
- D is recognized by the enzymes of the digestive tract but L is not
where does glucose come from
- commercial produced by hydrolysis of corn starch
- major end product of carb digestion
- ruminants produce FVA
where does galactose come from
- glucose + lactose = found in plants
- component of galactolipids found in plants
where does fructose
- sweetest of all sugars ( fruits and honey)
- component of sucrose
how do you turn B-D ribose to B-D-2- deoxyribose
removal of oxygen from the second carbon
what is the main function of ribose
combined with adenine it makes adenosine and 3 phosphates to make ATP
what is ribitol
compenent of riboflavin (B2)
how can beta and alpha bonds effect monogastric digestion
- monogastric
enzymes can digest alpha bonds like starches but not beta linkages like cellulose
are ruminants able to digest beta bonds
yes, most forages found in ruminant diets are beta linkages
where is lacrose naturally found
in milk
- galactose and glucose in B(1-4) glycosidic bond
broken down by lactase
when is lactase expression most present
- early on in birth, can fade during life span = lactose intollerant
what is maltose used for in digestion
- partial hydrolysis of starch yields maltose
what is the difference between homo/ heteropolysaccharides?
homo - the same monosaccharide units = starch, thats only made of glucose - alpha
heter - made up of more then one monosaccharides
hemicellulose , glucose and others
what are the two different types of starch granuels
- amylose
- amylopectin
What is amylose
- long branch chains of glucose connected by a (1-4) linkage
- soluble in water - bur will adopt hylic structure, reducing the area for enzymes to digest = so its less digested
- 20-30% of starch in cereal grains
- also called resistance starch
what is amylopectin
- branched - chained polymer with a (1-4) and a (1-6) linkages
- compromises 70-80% of starch in cereal grains
- de-branching enzyme a 1-6 requires glucosidase for digestion
- its rapidly digested because of its branched surfaces = more surface area for enzyme to digest it
what is glycogen
- very similar to amylopectin, more highly branched
- a(1-4) and a (1-6) linkages at branch points
- storage form of glucose in animals (readily available energy source)
- stored in liver and muscles
what is the difference between glycogen storage in the liver or in the muscles
- liver = the glycogen is used locally
- muscles = has to travel through the blood stream
what is cellulose
- long linear polymer of repeating glucose units in B(1-4) linkage (starch is a (1-4)
- insoluble in water
indigestible by mammalian enzymes (by fermitative enzymes)
what is hemicellulose
- hterogeneous group of polysaccharide substances
- sugars in backbone, sidechains
- in the backbone (xylose, mannose, galactose)
- arabinose, glucuronic acid, galactose) side chain
- B (1-4) linkages
- makes up cell wall will celulose and lignin
- can be fermented
what is lignin
- not a carb
- highly branched poly-phenolic polymer composed of phenol units with strong bonding
- indigestible by mammalian enzymes ; resistant to microbial enzymes
- plant content of lignin increases as plant matures
what is pectin
- part of the plant cell wall
- not digestible for mammals
- backbone = a(1-4) linked galacturonic acid units
(sugar = xylose, galactose) side chains - microbial fermentation
what is B glucans
- homo polymers of glucopyranose units with B(1-4) and B(1-3) linkages
- water soluble and highly fermentable
- used commercially as functional fiber
how do you combat B glucans in poultry diets and why is it necessary
- because poultry has viscous intensional fluid, it interferes with digestion
- B- glucanase is added to poultry diets containing barely or oats
- without this the nutrients are less digestible
what is soluble xylans
- B linked xylose backbone, arabinose side chains ( cause poor digestibiliy in poultry)
- rye, wheat major sources
why is xylanase added to poultry diets
- its an enzyme to degrade xylans so it can become viscose
what is the difference between dietary and functional fiber
- dietary is the whole plant
- functional is extracted from the plant and bottled
what are the physiological effects of fibers
- soluble in water
- water- holding capacity and viscosity ( slows down gastic functions, to feel full for longer and eat less - reduces food intake, energy and fat absorbtion)
- absorbtion or binding ability ( fiber is able to bind to fat = digestibity goes down, reduction in cholesterol absorbtion)
- degradability/ fermentability ( when fermented in the large intestine, promotes growth of beneficial microorganisms = due to slight pH change from VFA prebiotics)
what are the basics in carbohydrate digestion in monogastrics
- only monosaccharides can be absorbed from GIT (starch has to be broken down into monosaccharides)
- polysaccharides/ disaccharides are hydrolyzed by digestive enzymes to monosaccharides
- source of carbohydrase activity (all the enzymes in the digestive tract)
- mammalian enzymes can only breakdown a linkages
- principle CH2O fed to monogastrics in starch
what are the sources of carbohydrase activity
mouth, pancrease, small intestine epithelial linning ( willi and microvilli)
what is the carb breakdown in the mouth
- short residence time in mouth - starch and dextrins are moving on because of limited time
- salivary amylase - can only breakdown a (1-4) linkages
what is the carb breakdown in the stomach
- pretty much nothing happens to carbs
- HCL is in stomach
- salivary amylase - deactivated from pH, no carb digestion
what is the carb breakdown in the small intestine
- mostly in the first two compartments (duodenum and jejunum)
- amylose, amylopectin and dextrose
- pH neutralized by bicarbonate ions from pancrease = a buffer
- pancreatic alpha amylase - a (1-4) linkages, produces maltose and limits dextrins
- maltose is further degraded by maltose to produce 2 glucose units
- a dextrinase breaks down limit dextrins a 1-6 linkages
what are brush border enzymes
- located on villi and microvilli
- contain beta 1-4 linkages
what is the absorption of monogastric
- greatest capacity in duodenum and jejunum
- little ileal absorbtion
- very little if any, stomach and large intestine absorbtion
- active and facilitated transport
how are monosaccharides transported
- enter portal circulation for transportation to liver (heavily involved in in metabolism, converts to glucose derivative)
- galactose, fructose converted to glucose derivatives via phosphorylation reactions (enter glucose metabolic pathways )
- glucose metabolized by the liver ; largly released into peripheral circulation (muscle adipose mammary glands
- glucose trasnporters
what is GLUT1
basic supply of glucose to cells
what is GLUT2
low infinity transporter; glucose from enterocyte to blood
what is GLUT3
high affinity transporter for brain and other glucose-dependent tissues
what is GLUT4
insuline sensative - in muscles and adipose tissues
what is GLUT 5
for fructose
what is the difference in storage of dipose tissue and skeletal muscle for glucose
adipose - glucose used stored fatty scids synthesized as tryglycerides to fat
skeletal muscels - excess glucose stroed as glycogen
during oxidation how many moles of ATP are created
38
what do ruminants get from microbes
- VFA’s and microbial proteins
- breakdown B linkages
what kind of diets do ruminants have
- survive on diets of high fibre that is mostly structured carbs
- fermatative digestion allow extraction of energy from high fibre diets
what does a high fibre diet look like
- there is more chewing, so more saliva and amylase is produced
- ferments = cellulose hemecellulose and pectin to produce more
acetate - this will creat more cellulolytic bacteria
what does a high starch diet look like
- more acidic so it will create more amylolytic bacteria producing VFA’s propinoate
- ferments amylopectin and amylose,
how does the level of feed intake effect VFA production
- the animal that eats more will create more VFA, becasue there is more substrate avaliable - higher proponoate and more amylitic bacteria
- the animal that eats less = higher acetate, less salivia and higher pH = more acetate and celylitic bacteria
how does the frequency of feeding effect VFA production
- animal eating once a day = pH goes down = more amylelytic bacteria and propinoate
- smaller amounts of feed = more stable pH which leads to more cellulolitic bacteria and more acetate produced
how do the size of the forage particles effect VFA production
- larger food particles = more chewing and salivary amylase = cellulitic = acetate more rumination and higher pH
what do buffers do
- more buffering lowers the pH making it less acidic and encouraging cellulolitic bacteria and acetate
what does rumensin do
- increases propinoate
how can you increase acetate production in rumen
- feed more frequently
- increase amount of dietary forage or roughage
- grind feed more coarsely
- include buffers
how can you increase propionate production in rumen
- feed less frequently
- increase amount of concentrate
- grind feed more frequently
- include rumensin
what is rumensin
- very common feed additive in beef, dairy diets
- increases gram negative bacteria in rumen / decreases gram positive bacteria
- increases propionate, less methane and increases feed efficiency
- imporves milk production reduces risk of acidoses
how are VFAs absorbed
- across the rumen wall into the blood
- passive and facilitative diffusion
- acetate, butyrate metabolized into ketone bodies
why are circulating blood (glucose) lower in ruminants than in monogastrics
- monogastrics rely on the glucose from absorbtion of the small intestine
what is feedlot bloat
- distension of left flank, abdomen ; causes laboured breathing
- viscous, frothy rumen contents prevent eructation
how can you fix bloat
- anti foaming agent
- trochar to puncture rumen
what is a dry bloat
- physical blockage
- damage of the vegas nerve - GI tract to the brain
- if there is damage to the brain the animal cant get rid of contractions
how do you use a trochar
- inserted into sub-lumbar fossa
- in severe cases
what is the difference between using a trochar for froathy bloat and dry bloat
- froathy = cut incision and open with fingers to pour in anti froathing agent
- dry gas bloat = quick release of gas
what can cause frothy bloat and why
high grain diets with not enough fibre will cause slimy bacteria
- rapidly growing pasture - alfalfa and clover
what are symptoms of Sub acute rumen acidosis
- reduced or erratic feed intake - eat less and less each day
- reduced milk fat test
- reduced rumination
loose manure; undigested grain in feces
poor performance
lameness
