Vitamins and minerals introduction Flashcards
When do animals need vit/mineral supplements?
When producer or owner making own food
*feed premixes should be nutritionally complete
Ca and P demands
Need to ensure supplementation
*Vit D increases Ca absorption
Eg. Raw diets often deficient in vit D, Ca, P… leading to increases in bone fractures
Water soluble vitamins
-All vit Bs and vit C
*use chemical names of B vitamins except B12
Fat soluble vitamins
Absorption of microminerals
Most microminerals (except I and Se) form salts and other compounds which are relatively insoluble so not absorbed
-minerals need carrier proteins
Chelation
Metal ions are reactive and must be chelated to prevent oxidation in body
*metals form complexes with organic ligands (either neutral or anionic chemical groups; often proteins and AAs) and must be delivered to important sites
Transport of trace elements
Trace elements must bind to specific transporter to move in blood
Mineral storage
Most mineral storage is very high and deficiency will take weeks to years
*except Na and K
What are macrominerals and where are they stored?
Ca, P, Mg
stored in bones
What are important microminerals and where are they stored?
Fe, Cu, Zn, Se, Cr, and others
stored in liver and often linked with specific storage proteins
Define vitamins
Organic nutrients needed in small quantities for a variety of biochemical functions
-usually not synthesized in the body; need to be from diet
Kinetics of water soluble vitamins
Absorption:
all B vits and Vit C absorbed passively at high levels in gut and by Na-dependent active transport at low levels in gut
Excretion:
-excreted in urine
*toxicity is rare
Storage:
limited except B12; need regularly in diet
B vitamin bacterial synthesis in monogastrics vs ruminants
Monogastrics
-some B vit production in ceca and hindgut but absorption in hindgut is limited
Ruminants
-rumen bacteria synthesize B vitamines and Vitamin K
*microbes produce more than ruminants need
Water soluble vitamin production in horses
Normal horse can produce most B-complex vitamins in adequate amounts in intestinal tract
*young growing foals, and horses under stress may benefit from B vit supplement
Rabbits and coprophagy
-fermentation in cecum produce cecotrophs
-soft cecotrophs consumed directly from anus
-provides needed B vitamins and Vit K
**also practiced by dogs, rats, gorillas
Fat soluble vitamin (Vit A, D, E, K) absorption
- In GI system , same was as dietary fat
- then transported to the liver in chylomicrons
- Vit A, D, K stored in liver, and vit E stored in adipose
Excretion of fat soluble vitamins
Not excreted in urine; instead in bile and feces
-Vit A and D toxicity can occur because they are stored
What type of derivatives are fat soluble vitamins?
Isoprene
Purpose of vit D
Not a true vitamin, it is a hormone that regulates Ca/P metabolism
What vitamins and minerals are considered electrolytes?
Na
K
What vitamins and minerals are involved in bones?
Ca
P
Mg
Vit D
Vit K
What vitamins and minerals are energy releasing vitamins?
Thiamin
Riboflavin
Niacin
Pantothenate
Biotin
What vitamins and minerals are hematopoetic?
Folate
Vit B12
Fe
Cu
What vitamins and minerals are antioxidants?
Vit E
Vit C
Se
Functions of electrolytes
-maintain osmotic and electrolytic environment
-maintain Na/K gradient
Symptoms from deficiency of Na
-lethargy
-loss of appetite
-muscle weakness
-respiratory depression and arrest
Symptoms for deficiency of K
-elevated blood pressure
-muscle weakness
-respiratory depression
-cardiac arrest
Symptoms for toxicity of Na
-dehydration
-seizures
-coma
Symptoms for toxicity of K
-cardiac arrhythmia and death
Function of calcium
-bone strength and maintenance
-contributes to membrane potential (funny current of cardiac pacemakers)
-blood clots (Ca is cofactor)
-2nd messenger giving information from outside to inside the cell (NT vesicle fusion and release; muscle contraction)
-major component of milk
Absorption of Ca
Absorbed by 2 distinct mechanisms:
- Active transcellular absorption
-upregulated to increased Ca absorption when body Ca stores are low - Passive, paracellular absorption
-occurs all the time
-passive so rate depends on Ca diet concentrations
Where does passive paracellular absorption of Ca occur?
Jejunum and ileum
-when dietary Ca are moderate or high
-Ca comes through tight junctions into basolateral spaces around enterocytes and into blood
Passive Ca absorption for ruminants vs monogastrics
Ruminants: less iportant because rumen dilutes Ca in digesta
Monogastrics: up to 50% of absorption
Where does active transcellular absorption of Ca occur?
-duodenum
-upregulated when body Ca stores are low
3 steps of active transcellular absorption of Ca
- faciliated diffusion of calcium into enterocyte
- Transport across enterocyte
- Active transport into extracellular fluid (ATP >ADP)
What regulates the active transport of Ca?
Controlled by the amount of the carrier protein calbindin present within the cell
*Vitamin D receptor is activated by Vit D resulting in increased synthesis of calbindin
What inhibits Ca absorption?
- Inhibited by compounds (oxalates, phytates, phosphates) that form insoluble Ca salts
- undigested fats form Ca soaps
Ca excretion
A large portion of ingested Ca is not absorbed, and is excreted in feces
*low digestibility
How is Ca transported in blood?
Ca bound to gamma-carboxyglutamate residues in serum proteins (often albumin)
Vitamin Ks role in blood Ca transport
Vitamin K is a cofactor in the enzymatic production of gamma-carboxyglutamate and the activation of osteocalcin for Ca bone binding
*means that Vit K deficiency can lead to reduced bone density=osteoporosis
Warfarin and dicoumarol
Interfere with Vit K regeneration by inhibiting reductase
-acts as an anticoagulant
Vitamin K deficiency
-Human newborns have no Vit K stores and without supplement, can lead to hemorrhagic disease
-spontaneous hemorrhage in chickens and pigs
Sources of vit K
- plants and bacteria
-intestinal synthesis in ruminants (can be reduced by high feed antibiotics)
-Menadione synthetic source (but susceptible to oxidation if sunlight, moisture, choline, trace minerals)
Ca excretion
- Kidney- when Ca serum levels high
- Fecal- Secretion into intestinal lumen when calbindin is downregulated
- Sweat *small
Ca storage in bone
99% Ca in bones and teeth
*in hydroxyapatite form
Ca level regulation
Plant and animal Vit D precursors
Plant: Ergosterol
Animal: 7-dehydrocholesterol
Vitamin D synthesis
Precursors are converted to Vit D by sunlight UVB on the skin
*can be impaired by fur coat and being kept indoors
Role of Vit D
Measuring Vit D
We measure the precursor of Vit D = 25-hydroxy D3
**Be careful! This is assuming that the kidney is functioning and will be able to metabolize to active form
Calcitonin
-important in fish; unimportant in terrestrial animals
-opposite effect of PTH= absorbing Ca in bone
Estrogen role in Ca
-Regulates osteoclast and osteoblast populations
-when estrogen levels low, more bone resorbed= osteoporosis
**supplement estrogen=prevent osteoporosis in postmenopausal women
Phosphorus functions
*most abundant intracellular anion
-important bone mineral (75-85%)
-in soft tissue (15-25%)- cell membranes, ATP, RNA/DNA, NADP
Absorption of phosphorus
Either passive paracellular diffusion OR active transcellular transport (stimulated by Vit D)
Regulation of phosphorus
Excretion and absorption is regulated by PTH and Vit D
What happens when phosphorus concentrations are low?
-stimulates Vit D production
-decreases PTH secretion
-increases intestinal absorption of P
-increases serum phosphorus
What happens when phosphorus concentrations are high?
-increases PTH secretion and decreases Vit D production
-PTH decreases renal resorption of P
-decreases serum phosphorus concentrations
Ratio of Ca:P
Should be approx 1.2 : 2.1
**allows for max Ca absorption in monogastrics
Impact of excessive dietary P on Ca
High dietary P can lead to a decrease in the Ca absorption of small intestines
*results in large fecal losses and bone resorption
Digestibility of P
-Phosphate salts are highly insoluble in water
-animal feeds have lower phosphates and are more digestible/absorbed
-phytate is mostly insoluble plant compound that binds dietary cations preventing absorption
Where do you find phytate?
bran or husk of many grains, legumes and seeds
How do you solve the issue of phytate?
Treat plant based feed ingredients with phytase to reduce phytate levels and free phosphate
Ca and P sources
-Typically low in plant sources
-Ca sources cheap, P is expensive
-bone meal for P, only some Ca
What do you need to add in diets for get a blanced Ca-P ratio
- Meat meal for protein and pure phosphorus
- Dicalcium phosphate for phosphorus
- Limestone or calcium carbonate for Ca source
- bone meal for Phosphorus (minor Ca)
Ca, Vit D and phosphorus deficiency
- Rickets- young
- Osteomalacia- adults, poor pigment
- Osteoporosis- adults
*can see abnormalities of erythrocytes, leukocytes, platelets
*can see Pica (animals consuming dirt, chewing on pens)
Cage layer fatigue
-occurs in laying hens at peak production
-due to high Ca demands for egg shell production
-causes bone deformities, fractures, paralysis
-pullets should be fed high Ca to build up reserves and proper Ca, P, Vit D levels should be maintained in diet
Ca toxicity
Does not occu normally because excess Ca is simply not absorbed
P toxicity
Rare; usually due to kidney failure
Vit D toxicity
Results in calcification of soft tissue which can lead to hypertension, and renal failure
