3: Review of nutrients 1 Flashcards
(43 cards)
What is the key energy substrate for dog, cat and horse passing through the enterocyte?
Dog = starch (glucose)
Cat = protein (amino acids)
Horse = fibre (SCFA from fermentation)
How are nutrients involved in all basic functions of the body?
- act as structural components
- enhance (or involved in) chemical reactions of metabolism
- transport substances into, throughout or out of the body
- maintain body temperature
- supply energy
Essential, conditionally essential, non-essential
Essential: nutrient can not be synthesized by the animal, must be obtained in the food
Conditionally essential: a non-essential nutrient that becomes an essential nutrient when certain physiologic conditions result in relative deficiency
Non-essential: nutrient can be synthesized in adequate quantities by animals and are not specifically required in the food
Examples of conditions in which a nutrient may become conditionally essential
In early development, some systems may not be up and running at full speed
During lactation, gestation or rapid growth
What is digestibility? What is it influenced by
Percentage of food’s gross nutrient content released following mechanical and chemical digestive processes
Influenced by both food characteristics and the digestive efficiency of the host
What is bioavailability
The degree to which a nutrient becomes available to support metabolism after digestion and absorption
How is digestibility measured?
Measure what of the nutrient that was eaten is left in fecal material
CP intake - CP out in feces = CP digested
Apparent vs true digestibility
Apparent = nutrient intake minus nutrient excretion in feces
True = nutrient intake minus nutrient excretion in feces corrected for all intestinal endogenous losses
What are intestinal endogenous losses
Excretion of nutrients into gut due to cell turnover, intestinal secretions (e.g. enzymes), sloughing of intestinal cells
What are simple carbohydrates? examples
Monosaccharides: glucose, fructose, galactose
Disaccharides (degree of polymerization =2):
- maltose (glucose + glucose)
- sucrose (glucose + fructose)
- lactose (glucose + galactose)
What are complex carbohydrates? Examples
Oligosaccharides (DP = 3-10): fructo-, galacto-oligosaccharides
Polysaccharides (DP > 10):
- starch, cellulose, glycogen
What determines whether a carbohydrate is digestible by mammalian enzymes?
Type of glycosidic bond present
- alpha (e.g. starch) = enzymes
- beta (e.g. fiber) = microbes
Types of CHO’s digestible for mammalian enzymes? For bacterial enzymes?
Mammalian = sucrose, maltose, lactose, starch, glycogen
Bacterial = oligosaccharides, non-starch polysaccharides (cellulose, hemicellulose, pectin)
How do non-starch polysaccharides (NSP) relate to dietary fiber?
NSP + lignin = dietary fiber
Slide 10*
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What affects the digestibility of starch? Different types
Granular structure
Rapidly digestible starch: most starches in cooked and extruded petfood easily digested (leads to peaks/spikes in blood glucose)
Slowly digestible starch: raw or uncooked starch more slowly digested
Resistant starch (RS): some plant starches resist enzymatic digestion in the SI
What is the difference between amylose and amylopectin
Amylose is a slowly digestible starch (coiled) and amylopectin is a rapidly digestible starch (branched; broken down at multiple locations
Sources of starch? Is starch important in dog/cat diets?
Corn, wheat, rice, barley, oats, potatoes, pulses
Important in kibble but not canned foods
Functions of CHOs
- energy (ATP)
- source of heat
- DNA and RNA framework (ribose, deoxyribose)
- building blocks for other nutrients (non-essential amino acids, fat, vitamins, glycolipids)
- storage of energy
What is a prebiotic? Can mammals digest them?
A substrate that is selectively utilized by the host microorganisms conferring a health benefit
e.g. fermentable CHOs
No, e.g. need microbes to digest oligosaccharides
Functions of dietary fibre (4)
- increase in bulk and water in intestinal contents
- regulate normal bowel function: constipation, diarrhea
- fermentation end products (acetate, butyrate, propionate) important in maintaining health of colon
- fermentation decreases colonic pH (pathogenic bacteria are pH-sensitive, prevention of intestinal disorders)
Despite the benefits of dietary fibre…
it may reduce absorption of other nutrients
What requirements do dogs and cats have with respect to protein?
No crude protein requirement
Requirement for essential amino acids
Requirement for sufficient nitrogen to allow synthesis of non-essential amino acids
What is taurine? Needed for…
B-amino sulfonic acid normally made in all animals
Needed for taurocholic acid, critical element of opsin (eye function)
