Lecture 4 Flashcards
What 5 things are considered carbohydrates?
Sugars
Starches
Cellulose
Hemicellulose
Lignin
Are carbs an expensive or cheap source of energy?
Cheap Source!
What is the sweetest carbohydrate?
fructose
What is sucrose?
Fructose + Glucose
What is required to break down sucrose, is this found in most animals?
Sucrase
Not found in most animals - do not feed sucrose to pigs
What is one of the most important carbohydrates nutritionally?
Cellobiose
- Two molecules of Beta - D- glucose
What are the most important carbohydrates in terms of animal feeding?
Polysaccharides
WHat are two types of starch granules?
Amylose
Amylopectin
How does amylopectin differ from amylose?
Amylopectin has branch points and therefore needs a debranching enzyme
What is glycogen structurally similar to?
Amylopectin, but glycogen is more highly branched
is cellulose digestable by monogastrics?
No - b1,4 linkage
What occurs as hay grows?
The longer it grows the higher percentage of lignin it contains and therefore decrease in digestibility
Why must poly and disaccharides be hydrolyzed by digestive enzymes into monosaccharides?
GI tract can only absorb monosaccharides
What is the most important source of carbohyrase activity?
Pancreas
WHat is the principle carbohydrate fed to monogastrics?
Starch in cereal grains
What is an organ over rated as a digestive organ
Stomach
More of storage
Where is the principle site of carbohyrate digestion?
Small intestine
How many step process is digestion of polysaccharides?
Two steps
- Initial break down to disaccharides
- Cleavage to monosaccharides
where does most carbohydrate absorpition occur?
Upper cranial section of small intestine
- duodenum and jejunum
2 Mechanisms of transport?
Passive Diffusion
Active Diffusion
3 metabolic fates of aborbed carbohydrates
used as immediate source of energy - glycolysis
Used as precursor for glycogen production
Used as a precursor for fat synthesis
what is the main end product of carbohydrate digestion in monogastrics?
Glucose
why can ruminants be fed high fiber containing feeds?
Bacteria in rumen can break down Beta linkages
What are all carbs in ruminants broken down to?
Glucose to be used by bacteria not animal
What is the primary energy source for rumen?
VFAs produced by bacteria
3 types of VFAs
Acetate
Propionate
Butyrate
what is the principle VFA formed?
Acetate
How can we increase amount of acetate produced?
Feed high amounts of roughage
Think acetate -
think acetyl CoA
How do we increase propionate?
Increase levels of concentrate
What VFA is the only VFA that can be used to produce glucose?
Propionate
What is produced during acetate and butyrate production that isnt produced during propionate production?
H+
What is the golden rule for VFA production?
Anything that lowers rumen pH will favor propionate production whereas anything that increase pH will favor acetate production
5 factors affecting relative proportions of VFA
Level of feed intake
Frequency of feeding
Proportions of starch and fiber
Size of forage particles
Presence of rumen modifiers
4 ways to increase acetate
Feed more freuqently
Increase amount of roughage
Grind feed more coarsely
Include buffers
4 wyas to increas propionate
Feed less frequently
Increase amount of concentrate
Grind feed more finely
Include rumensin
