Lecture 2b - Review of Nutrients Flashcards
Energy is not a nutrient, so what is it derived from?
Macronutrients!
- lipids, carbohydrates and proteins
What happens with N and a carbon skeleton when fed an excess protein diet?
Excess protein diet = animal has excess aa
- through deamination the bond btw the N and C skeleton is broken
- C skeleton undergoes gluconeogenesis or ketogenesis
- 2 N will link to form UREA which is brought to the kidney and excreted
What happens when energy supply > use?
Animal would grow; excess energy stored as fat in adult animals
How is gross energy content in food determined?
With a bomb calorimeter
- burning of food and measurement of amount of heat released
What are the advantages to the net energy system?
- more precise than ME and DE
- actual energy amount that is available to the body from digestion and metabolism of feed
- efficiency of energy utilization
What are the disadvantages of net energy system?
- more experimental data needed
- heat loss must be measured
At present, what energy system is used in dog and cat nutrition?
Metabolizable energy (ME)
What is basal metabolic rate (BMR)?
The energy requirement for a normal animal in a thermoneutral environment, awake but without movement (resting) and in a postabsorptive (fasting) state
What is resting fed metabolic rate (RFMR)?
- The energy requirement for a normal but unfasted (fed) animal at rest in a thermoneutral environment
- Includes energy needed for digestion, absorption and metabolism of food (heat increment)
What is maintenance energy requirement (MER)?
The energy requirement of a moderately active adult animal in a thermoneutral environment
- includes energy needed for obtaining, digesting and absorbing food in amounts to maintain body weight as well as energy for spontaneous activity
- does NOT include energy needed to support additional activity (work, gestation, lactation and growth)
What is the most important nutrient?
Water
- if you without food and water, water gets the animal in trouble the fastest
- largest constituent of the body, varying from 40 to 80%
What are 3 sources of water?
- fresh (drinking) water
- water in food
- metabolism
How is water produced in metabolism?
When sugars are oxidized
- Glucose + O2 —> CO2 + H2O
What are the ways an animal losses water?
- Urine (largest loss (75-85%)
- Feces (second largest)
- Respiration (water vapor lost from lungs in exhaled air)
- Sweat
- Milk during lactation (85-90%)
What are the 4 fxns of water?
- Solvent to dissolve and transport substances
- Necessary for chemical rxns that involve hydrolysis
- enzymatic digestion of CHOs, fats and protein - Regulation of body temperature
- evaporative cooling - Provides shape and resilience to body
Water acts as a solvent to dissolve and transport what substances?
- ion balance across cellular membranes
- transport of nutrients within and among cells
- elimination of waste products through urine
What systems regulate the amount of water in the body?
- Neural and endocrine systems
What is dehydration?
Lack of water in body tissue
- >1% loss is when thirst drive kicks in
- 5-10% water loss in cells could result in death
What is hydremia?
Water intoxication. 2 animals who should not have free access to water:
- young animals that consume a large amount of water in a short time
- dehydrated animals
What happens in the body (cells) during dehydration?
Cells shrink and die off
- this is happening in the organ systems which leads to death in the animal bc organs are shutting down
What are 6 key defining factors about vitamins?
- required in very small amounts (ppm)
- not metabolic fuels or structural nutrients
- involved in fundamental fxns of the body
- regulators of rxns (catalysts)
- absence must cause deficiency syndrome
- not synthesized in sufficient quantities to support normal physiologic fxn
Are all vitamins essential for all species?
No
- some species are able to make certain vitamins while others are not
What are the number of essential vitamins for dogs vs cats?
Dogs: 3 fat-soluble and 8 water-soluble
Cats: 4 fat-soluble and 9 water-soluble
What are the 5 fat-soluble vitamins?
- Retinol - A
- Ergocalciferol - D
- Cholecalciferol - D
- Alpha-Tocopherol - E
- Phylloquinone - K
What are the 10 water-soluble vitamins?
- Thiamin - B1
- Riboflavin - B2
- Nicotinamide (Niacin) - B3
- Pantothenic acid - B5
- Pyridoxine - B6
- Biotin - B7
- Folacin (folic acid) - B9
- Choline - B4
- Cyanocobalamin - B12
- Ascorbic acid - C
Which vitamins are not essential for dogs and cats?
Not essential for either: Ascorbic acid (vit C)
Not essential for dog: Niacin (Vit B3), Phylloquinone (Vit K)
Which vitamins act as cofactors in enzymatic reactions?
All the water-soluble vitamins
What vitamin contributes to DNA synthesis?
Folic Acid (vit B9)
What vitamin contributes to energy release from nutrient substrates?
All the B vitamins
What vitamin contributes to Ca homeostasis and bone development?
Ergocalciferol and Cholecalciferol (vit D)
What vitamins contribute to normal eye function?
Retinol (vit A)
What vitamin contributes to cell membrane integrity?
Alpha-Tocopherol - E
Ascorbic Acid - C
What vitamin contributes to blood clotting?
Phylloquinone (Vit K)
What vitamin contributes to free radical scavenging?
Alpha-Tocopherol - E
Cyanocobalamin - B12
What vitamin contributes to amino acid and protein metabolism?
Niacin (Vit B3)
What vitamin contributes to nerve impulse transduction?
Choline - B4
Why are multiple vitamin deficiencies more frequent than single-vitamin deficiencies?
In pet food, all the vitamins are added as a pre-mix. If the pre-mix is not added all the vitamins are missing, not just one.
Do vitamins and metabolism interact? Are vitamins needed to help the body turn glucose and aa into energy?
YES
How are fat-soluble vitamins absorbed?
- require bile salts and fat to form micelles for absorption
- passively absorbed, mainly in duodenum and ileum
- transported in conjunction with chylomicrons to liver via lymph system
How are water-soluble vitamins absorbed?
- active transport
- some vitamins require a carrier protein called “intrinsic factor”
- sodium-dependent, carrier-mediated absorption pump
What are dietary vitamin sources?
Fortification with vitamin premix because meeting requirements from common ingredients is difficult.
- Effects of processing and storage on vitamin stability
- Availability
- Disputed vitamin requrements
What are vitamins are organ meats vs meat and plants rich in?
Organ meat: rich in fat-soluble vitamins
Meats, plants: Vitamin B’s, A, D, E
What is provitamin?
A compound that requires an activation step before becoming biologically active.
What is an example of a provitamin that cats cannot complete the activation step of?
Beta-carotene is cleaved by enzymatic processes releases two molecules of retinol (vit A)
- cleavage of Beta-carotene is the activation step
- cats cannot do this (dogs can) so they much have retinol added into the diet
What is a vitamer?
Chemically the same compound as a vitamin, may exert varying physiologic effects because it is an isomer
What are 4 different vitamers of B12 (generic term, Cobalamin)?
- Adenosylcobalamin
- Cyanocobalamin
- Hydroxylcobalamin
- Methylcobalamin
What 3 transport molecules does cobalamin (B12) need for absorption?
- Haptocorrin
- Intrinsic factor (produced in the stomach)
- Transcobalamin
What are vitamin-like substance?
Exhibit properties similar to those of vitamins but do not fit in strict definition of a vitamin. Have physiologic functionality, but questionable essentiality
What is an example of a vitamin-like substance? Why is it needed?
L-carnitine: transport of long-chain FA across mitochondrial membrane.
- without it, fat cannot be oxidized
- need a diet sufficient in lysine in order for the body to make it
What are minerals?
Inorganic elemental atoms that are essential nutrients.
> 18 mineral elements essential for mammals
What are the macro minerals, trace elements, and ultra-trace elements?
Macro minerals
- Ca, P, K, Na, Cl, Mg, S
Trace elements
- Fe, Zn, Cu, Mn, Co, Mb, F, Se, I, Cr
Ultra-trace elements
- Mo, As, B, Ni, Si, V
*macro and trace need to be added in a premix
What are the 3 functions of minerals?
- structural components of body organs and tissues
- Ca, P and Mg in bones and teeth - Constituents of body fluids and tissues (electrolytes)
- maintenance of osmotic pressure
- acid-base balance
- muscle contraction
- membrane permeability
- tissue irritability - Catalysts/cofactors in enzyme and hormone systems
- integral and specific components of structure of metalloenzymes
- less specific activators of metalloenzymes
What are the homeostatic regulations for minerals?
- Maintaining of mineral concentrations at active sties in narrow physiologic limits despite over- or under-ingestion
- Control of intestinal absorption and excretion
- Urinary excretion
What will be the homeostatic regulation with low mineral levels in the diet?
- will try to reduce fecal excretion
- will try to upregulate absorption
- will try to limit urine excretion
What are the 5 factors influencing mineral bioavailability?
- Chemical form (mineral solubility)
- Other dietary components that interact metabolically
- Age, gender and species of animal
- Intake of mineral and the need (body stores)
- Environmental factors (organic vs inorganic minerals
Why are meat-derived minerals more available than plant-derived minerals?
Animal has poor ability to digest phytate (which is where a lot of P is tied). Need to add more bioavailable sources of P or add an enzyme that breaks up the phytate molecule. Phytate can also impact absorption of trace minerals such as Zn and Ca.
What are the mineral sources relevant for dogs and cats?
Ca: bone, meat meals, inorganic sources
P: meat, oilseeds, grains, inorganic sources
Mg: meat meal, oilseeds, grains, inorganic sources
Trace elements: inorganic sources
Mineral premixes
What is the “meat factor” effect?
Referring to meat derived foodstuffs being more available than plant sources
- provides and available form of mineral
- enhances absorption of the mineral supplied by the rest of food
Why are organic minerals more available than inorganic minerals?
Possibly, because mineral is complexed or bound.
- Cannot be sequestered by other dietary components
