Minerals Flashcards
What are the main functions of minerals?
- constituents of skeleton structures
- maintenance of osmotic pressure
- regulation of acid base balance
- components of enzymes
- activators of enzymes
- components of biological units
What are the main functions of minerals?
- constituents of skeleton structures
- maintenance of osmotic pressure
- regulation of acid base balance
- components of enzymes
- activators of enzymes
- components of biological units
What are the macro-minerals?
> 5g in body
Ca, P, Mg, K, Na, Cl, S
Which minerals are concentrated by plants and why?
Cu, Zn, Fe, Mn, Mb
- mineral by products from industry and manufacturing
Which minerals are concentrated by plants and why?
Cu, Zn, Fe, Mn, Mb
- mineral by products from industry and manufacturing
What minerals are involved in bone metabolism
The most important role of minerals in the horse’s diet is the development in mineralized tissues
Bone in metabolically active tissue and requires:
- supply of Ca and P
- other minerals - F, Mg, Mn, Zn
- osteoblasts, osteoclasts
- calcitonin, parathyroid hormons
What are the micro- minerals
Which minerals are concentrated by plants and why?
Cu, Zn, Fe, Mn, Mb
- mineral by products from industry and manufacturing
Relationship between dietary levels and absorptive efficiency
absorptive efficiency tends to decrease when intake increases
What minerals are involved in bone metabolism
The most important role of minerals in the horse’s diet is the development in mineralized tissues
Bone in metabolically active tissue and requires:
- supply of Ca and P
- other minerals - F, Mg, Mn, Zn
- osteoblasts, osteoclasts
- calcitonin, parathyroid hormons
What happens to bone resorption during times of physiological stress?
The skeleton maintains structural integrity and regulates calcium homeostasis –> bone can be resorbed and remodelled
What are the functions of calcium?
Structural function - bone crystals = hydroxyapatite
- 99% in bone/teeth
= 1% found in soft tissues where it is involved in muscular activity, blood clotting, hormone secretion and enzyme activation
- Ca:P in bone = 2:1
What is the result of calcium deficiency?
Although horses are good at recognizing some deficiencies (Na) they are not good at recognizing Ca
- rickets
- osteomalacia (in mature animals)
- nutritional secondary hyperparathyroidism
- lactating mares –> decrease milk production (but Ca and P remain the same)
What hormone regulates calcium concentrations?
PTH
- maintains calcium homeostasis in blood
- mediated by vitamin D (calcitriol)
- PTH + calcitriol act on the bone and kidneys to maintain plasma Ca levels
low Ca –> parathyroid –> calcitriol –> Ca binding protein –> Ca reabsorption + absorption
Where does Ca absorption occur?
small intestine
- passive and facilitated diffusion
Ca absorption efficiency varies with:
- age (70% in young, 50% in mature)
- diet (low Ca increases absorption; high P binds Ca)
- stage of training
- stages of gestation/lactation
What is the result of calcium deficiency?
Although horses are good at recognizing some deficiencies (Na) they are not good at recognizing Ca
- rickets
- osteomalacia (in mature animals)
- nutritional secondary hyperparathyroidism
What is rickets?
- failure of vascular invasion and mineralization in the area of calcification of the physis
- bone pain, stiff gait, swelling in the area of the metaphyses, difficulty rising, bowed limbs, pathologic fractures
What is nutritional secondary hyperparathyroidism?
AKA Miller’s Disease, Bran Disease or Big Head Syndrome
- results from excess P
- lameness
- enlarged facial bone –> fibrous connective tissue invades area where bone was resorbed
- P binds to Ca –> Ca from bone is resorbed to compensate for deficiency
Calcium toxicity
- high dietary Ca levels interfere with absorption of other minerals (e.g. P, Mg, Mn, Zn)
- brittle bones
- horses can handle high calcium levels (up to 7:1)
What are calcium requirements dependent on?
- vitamin D supply
- phosphorus supply
- rate of growth
- physiological state
- presence of oxalic acid and physics acid
P deficiency
Similar to Ca and vitamin D
- occurs when P is in an unavailable form (phytic acid or phytate)
Sources of Ca
- animal sources (e.g. meat meal)
- milk
- grains low
- roughages borderline
- concentrates and complete rations should be balanced and supply = 2:1
What are the functions of P?
- major constituent of bone (14-17% skeleton)
- required for many energy transfer reactions
- synthesis of phospholipids, nucleic acids, phospho-proteins
When is P very important?
reproduction, gestation, lactation
P deficiency
Similar to Ca and vitamin D
- occurs when P is in an unavailable form (phytic acid or phytate)
Ca levels and exercise
Exercise –> change in extracellular concentrations
- Increased Ca can help
Functions of Na
Found in mainly extracellular fluid and small amounts found in skeleton
- acid base balance
- osmotic pressure
- absorption of CHO and AA
What is the result of sodium chloride deficiency?
- poor growth (decreased feed intake)
- reduction in utilization of CHO and protein
- PICA appetite (horses will eat ANYTHING to obtain salt; very sensitive to salt)
Where are Na and Cl absorbed?
small intestine
- excreted via sweat & urine
- 0.5-1% diet
benefits to providing salt block
- easy to provide
- stimulates salivation
- no danger for over-consumption
- horses may have difficulty obtaining enough
- must provide adequate water (stimulates drinking)
How does the body compensate when dietary sodium is low?
- decrease in urine & sweat production –> could compromise performance an water balance)
- can resorbs from kidneys or see it (lick themselves, saddle pads, eat dirt)
What is the result of sodium chloride deficiency?
- poor growth (decreased feed intake)
- reduction in utilization of CHO and protein
- PICA appetite (horses will eat ANYTHING to obtain salt; very sensitive to salt)
Where can a lot of iodine be found?
75% in the thyroid
- component of thyroxine which helps control basal metabolic rate
What is hyperthyroidism?
reduced thyroxine –> drop in BMR –> weight gain
What does a deficiency in iodine lead to?
A decrease in the production of thyroxine
- foals born with goiter
- foals can be stillborn, or weak & hairless
- when mares are grazing on iodine deficient soil –> should be given iodized salt blocks
Iodine toxicity
Horses are very sensitive (can tolerate levels of 5 ppm vs. other species 200-600 ppm)
Why is it important to consider Se levels
soils low in Se –> white muscle disease
soils high in Se –> can result in toxicity = alkali disease or blind staggers
Deficiency of iron?
- decrease in # of RBCs
- may occur in horses that are heavily parasitized due to bleeding after worming
Why do horses have higher requirements for iron than adults?
- milk is a poor source of iron
- provide creep feeds that allow foal access but prevents mares
What is the function of selenium?
- closely related to that of vitamin E and other antioxidants
Why is it important to consider Se levels
soils low in Se –> white muscle disease
soils high in Se –> can result in toxicity = alkali disease or blind staggers
Functions of zinc
- found in hair, skin, bone
- acts as enzyme activator or is a component of an enzyme (specifically enzymes involved in keratinization)
- Zn is a cofactor for over 200 reactions
- often works in combination with B-carotene
Zinc deficiency
poor skin, hair
Functions of Mg
- constituent of bone and teeth
- enzyme activator
- depends on levels of Ca, P, Zn in diet (BALANCE minerals)
- increased Ca and P will decrease digestibility of Mg
Mg deficiencies
- nervous system disorders, hyper irritability, tetany (often precipitated by stress)
- grass tetany = rare but can occur on fast growing pasture, in lactating mares or horses in transit or fasting (high stress)
- nervousness, tremors, staggering, convulsions, death
Mg is calming
Functions of copper
- involved in synthesis of Hb
- involved in bone formation
- oxidation-reduction enzyme systems
Deficiency of Cu
anemia (Hb) or thin weak bones
Cu toxicity
not seen in horses
Which minerals are significantly involved in bone maintenance, structure, or formation?
Ca, P, Cu, Zn, Mg
Why could a deficiency in salt result in poor growth or performance?
Na+ is needed for the absorption of carbohydrates and amino acids, as Na+ dependent transporters in the small intestine are responsible for absorbing these nutrients.
