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Monogastric Nutrition
Flashcards for monogastric nutrition
34
Veterinary Medicine
Professional
05/28/2010

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Cards

Term
What is digestibility, and what is it measured as?
Definition
Digestibility is the fraction of a nutrient that disappears from the gut, and it is measured as the difference between what goes in and what comes out in the feces. 
Term
What is apparent digestibility?
Definition

The fraction of nutrients dissappearing from the gut without regards for microbial fermentation products, endogenous protein sources, and/or mucous secretions, which are not utilized.

AFD=(nutrients in-nutrients out)/intake

Term
How does the hindgut affect apparent digestibility?
Definition
It adds proteins and energy to the tract via microbial fermentation. 
Term
What is true fecal digestibility?  How does this differ from apparent?
Definition
True fecal digestibility is the amount of nutrients absorbed from the small intestine; TFD=(nutrients in-nutrients out-nutrients from endogenous sources)/intake.  Unlike apparent, true fecal digestibility accounts for nutrient sources in the hindgut that are not used by the animal. 
Term
Besides fecal digestibility, what is another way of measuring digestibility?  How can this be done?
Definition
Ileal digestibility is another method, and this can be done by cannulation, using a marker, and by performing ileal-rectal anastomosis surgery, where a tube is inserted into the animal's small intestine at the ileocecal junction, and the feed marker gives an idea of the nutrient concentration in the food. 
Term
Where would it be best to measure protein and amino acid digestibility?  In the ileum or the feces?  And why?
Definition
Ileal method is best because in the colon, microbial fermentation of amino acids takes place, as well as sloughed cells and mucinous secretions, which affect the apparent digestibility.  Protein digestion occurs in the small intestine, so measuring from the ileum will give an indication of how much protein was actually used. 
Term
Why is it not as important to measure fatty acids in the ileum when measuring digestibility as it would be for proteins?
Definition
While microbials produce short chain fatty acids in the colon, they do not produces long chain ones.  Therefore, it is more important for short chain fatty acids than for long. 
Term
Why can you measure minerals in the feces when determining their digestibility?
Definition
Microbials don't produce minerals, and lots of mineral absorption occurs in the colon. 
Term
How does the physical form of feed impact digestibility?  In particular, consider the size of feed particles- large vs. tiny and finely ground, and very, very tiny
Definition
The size of the feed particle impacts the surface area that can be attacked by digestive enzymes- finely ground particles are more easily digested than larger particles, like whole grains, because they have a smaller surface area for attack.  Very, very finely ground feeds can clump in the GIT and decrease digestibility. 
Term
How does a lower intake impact digestibility?
Definition
Lower intakes signify higher digestibility because the animal doesn't eat as much, so less has to be pushed through the GIT. 
Term
What is gelatinization, and what does this do for digestibility?
Definition
Gelatinization is heating starch with water, which incorporates water molecules between glucose polymers and increases digestibility. 
Term
What are important factors inherent to animals when considering digestibility?
Definition

The type of gut

Digestive enzymes available

Adequate dentition

Healty

Term
Why does an herbivore have a greater apparent digestibility for proteins than a carnivore?
Definition
Herbivores have longer GIT and hence the food is in the GIT for a longer time, so there is more time for digestion and absorption.
Term
What will feeding high fiber to a monogastric animal do to digestibility of other nutrients?
Definition
The other nutrients will become diluted, with an increased rate of passage through the GIT and less time for digestive enzymes to act. 
Term
Define availability of a nutrient
Definition
The ability of a nutrient to be absorbed and used by the body; the nutrient is free from bonding to other molecules and from other chemical modifications that would stop its use in absorption or metabolism. 
Term
which amino acids are available to animals (D or L)?  How might this be a problem in synthetic mixtures?
Definition
L, although some animals can convert D to L.  Synthetic mixtures are often racemic. 
Term
How does heat treatment impact availability?
Definition
It denatures proteins and destroys vitamins, so although the food might be digestible, the amount of nutrients that can be absorbed and utilized is much less. 
Term
Problem with phytate and availability
Definition
Phytate binds to phosphorous in food, and so the digestibility is reduced; as a result, phosphorous is excreted in the feces and presents issues with waste removal. 
Term
Differences between digestibility and availability?
Definition
Digestibility assumes absorption- it is the fraction of a nutrient that disappears from the lumen of the GIT.  Availability is the fraction of a nutrient that is able to be absorbed and is in a form that can be used; it is available to be metabolized. 
Term
What is metabolic need?
Definition
A reflection of the rates of metabolic pathways that utilize the nutrient in question, dependent on genotype and physiological/developmental state.
Term
What are maitenance requirements?
Definition
The amount of a nutrient needed to maintain a constant physiological state of well being. 
Term
What are four reasons why an animal would need more energy than maitenance would allow?
Definition

Illness

Pregnancy

Lactation

Growth

Term
Define recommended daily allowance
Definition
The recommended intake that reduces nutrient deficiency in some desired proportion of the population while avoiding excessive intake. 
Term
Define nutrient requirements
Definition
The amount of a nutrient needed to maintain a given physiological state. 
Term
What is a nutrient?
Definition
Any chemical compound or element in the diet which sustains normal reproduction, growth, lactation, or maitenance
Term
What are essential nutrients?
Definition
Those which are required in the diet
Term
What are the essential fatty acids?
Definition
Linoleic acid, linolenic acid, arachidonic acid (carnivores)
Term
What are the 11 essential amino acids?
Definition
phenyalanine; valine; threonine; tryptophan; isoleucine; methionine; histidine; arginine; leucine; lysine; taurine
Term
What are the main essential vitamins? Minerals?
Definition

vitamins: A,D,E,K,cobalamin,thiamine,riboflavin,panathanoic acid, niacin, pyridoxin, folic acid, biotin, choline

 

minerals: calcium, phosphorous, potassium, sodium, chloride, magnesium, iron, copper, manganese, zinc, iodine, selenium

Term
what factors affect nutrient requirements?
Definition

type of GIT, age, type and level of productivity:

growth- nutrients to into making tissues, protein turnover

lactation- nutrients into milk production

reproduction- nutrients into fetus

physical activity

 

Term
What does the NRC do?  What is the epidemiological approach to finding requirements?
Definition
The NRC looks at different ways to define requirements.  The epidemiological approach looks at the measurements of the intake of a given nutrient to a population of healthy animals. 
Term
What is the dose response approach?  What are possible variables to use in measurement?
Definition
Administration of various levels of a nutrient to animals, and measuring a particular response.  Variables can be: weight gain, nitrogen balance, urea excretion, plasma urea concentrations, amino acid oxidation, prevention of clinical signs of deficiency
Term
How would you use dose response to determine lysine oxidation? 
Definition
Feed diets with differing amounts of lysine, and measure the rate of lysine oxidation.  Feed isotopes, then take sample of breath and look at carbon dioxide levels. 
Term
What happens if an animal lacks a particular essential amino acid in the diet?
Definition
Protein synthesis can't occur, so the other amino acids get oxidized. 
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