Minerals and vitamins Flashcards
Define mineral
Inorganic element
Define macro-element
Required in large amounts
Define micro-element/trace-element
Lower amounts needed
Define bioavailability
Ease of extraction from a source
Define pica
Eating non-food sources, can be indicative of a depraved appetite
Define vitamin
Organic compounds that are required in small quantities for normal growth and maintenance of animal life (can be fat or water soluble)
Define pro-vitamins/vitamin precursors
Many vitamins consumed as non-active dietary form which requires chemical change to function as the vitamin
List the essential fat soluble vitamins
- A (retinol)
- D2 (ergocalciferol)
- D3 (cholecalciferol)
- E
- K (phylloquinone)
List the essential water soluble vitamins
- C (ascorbic acid)
- B complex (thiamin, riboflavin, nicotinamide, pyridoxine, pantothenic acid, biotin, folic acid, choline, cyanocobalamin)
List the essential macro minerals
- Calcium
- Phosphorous
- Magnesium
- Sodium
- Potassium
- Chloride
- Sulphur
List the essential trace elements
- Iron
- Zinc
- Copper
- Iodene
- Manganese
- Molybdenum
- Cobalt
- Fluorine
What is deficiency?
- Not having enough of something
- Leads to death
What is toxicity?
- Having too much of something
- Leads to death
Describe bioavailability
- Just becuase something is present does not mean it can be extracted or, in the case of proteins, that it has the correct AA profile
- Depends on chemical form, other compounds that can interact, age, gender, species, body stored, environmental (organic or inorganic)
Explain the relevance of soil consumption
- Pica/geophagy
- Ruminants eat grass, ripping action, likely to ingest soil
- More likely to eat soil in wet weather
- Also when very windy and dry
- Likely to have high normal ingestion of soil
- Soil contains some impotant nutrients
What is the role of sulphur in the body?
- In proteins containing cystine, cysteine and methionine
- Also in vitamins (biotin and thiamin), hormones (insulin, oxytocin), metabolites (CoA), chondroitin sulphate (cartilage, bone, tendons, blood vessel walls)
Describe the occurence of sulphur deficiency
- Mostly ruminants
- Sulphur deficiency is also protein deficiency in non-ruminants
- Feed ruminants non-protein nitrogen sources, divorces sulphur and protein
- Enough protein but not enough sulphur
- Wool approx 4% sulphur, woolier more likely to be deficient
What are the effects of sulphur deficiency?
- Decreased fibre quality, eventually shed
- Decreased rumen function
- Increased salivation and lacrimation
- Growth retardation, emaciation and death
Describe sulphur toxicity
- Excess dietary sulphur converted to H2S
- May cause reduced rumen motility, nervous and respiratory distress
- Has major role in other mineral interactions (iron and copper, copper and molybdenum, copper and sulphur)
Outline the nutritional needs during pregnancy and lactation
- Aim for ideal BCS before mating
- Last 3 weeks of pregnancy change diet
- Do not supplement Ca and vit D
- Feed small, frequent meals near end of gestation
- Growth type diet
- Feed free choice at peak lactation
- High caloric density, increased protein, inreased calcium
Outline the nutritional needs of senior cats/dogs
- Change to senior type food
- Higher in fibre,essential fatty acids, zinc and B vitamins
- Risk factor management for geriatric disease
- hgih levels of dietary antioxidants
- Smaller, more frequent meals
- Alter feeding amount to maintain optimum body conditions
Explain the importance of a carnivorous diet for cats
- Need taurine, arachidonic acid and pre-fromed vit A
- Only found in animal tissues
- Insufficient taruine leads to cardiomyopathy adn irreversible blindness
- Higher pH than 6.2-6.4 risk bladder stones
- Contrlled lgel of magnesium to help prevent feline lower urinary tract disease
- Wet ratehr than dry to avoid FLUTD
- Need pre-formed retinoids in diet, do not utilise carotenoids
Outline rabbit nutrition
- Long fibre essential (dental, behavioural)
- Protein 13-18% DM
- High quality protein
- No added dietary fat required
- Cits A, D and E required in diet
- Coprophagy
Outline guinea pig nutrition
- Similar to chinchilla
- Coprophagy
- Provide vit C, cannot synthesise it
What is the function of vitamin K?
Maintenance of normal levels of blood clotting proteins (II, VII, IX, X, protein C and protein S)
What are the sources of vitamin K?
- Exists naturally as
- K1 (phylloquinone) in green vegetables
- K2 (menaquinone) produced by intestinal bacteria
- Also K3 as synthetic mendione
Briefly describe the forms of vitamin K
- naturally occuring are fat soluble
- Absorbed from intestine only in presence of bile salts and other lipids through interactions with chylomicrons
- Synthetic is water soluble, absorbed irresepctive of presents of intestinal lipids and bile
How does vitamin K deficiency occur?
- Fat malabsorptive diseases
- Long term antibiotic use (stops bacterial production of K2)
- Intestine of newborns sterile if infant lacking from early diet
How does vitamin K carry out its function?
- Cotting proteins synthesised as inactie precursor proteins
- Conversion from inactive to active requries post-translationa modification of specific glutamate residues
- Modification is decarboxylation and enzyme responsible requires vit K as cofactor
- Reduced hydroquinone form of vit K converted to 2,3-epoxide form
- Regeneration of hydroquinone form requires uncharacterised reductase
Describe the clinical signs associated with products that interfere with vit K function
- Anticoagulants
- Warfarin similar shape to vit K
- Takes vit K’s place in regernation of hydroquinone form using uncharacterised reductase
- Coumarin toxicity results in coagulopathy and patients present with bleeding tendencies
Describe calcium absorption within the GI tract
- Absorbed passively and actively
- Controlled by calcitriol, parathyroid hormone and calcitonin
- Calcitriol and parathyroid hormone increase GI Ca absorption
- Calcitonin decreases it
- Absorption increases with increasing calcium concentration in intestine (by diffusion mostly)
- When requirement for calcium high but Ca of feed is low, increased active transport
How does calcitriol increase calcium absorption?
- Stimulates active transport
- Increases synthesis of calcium-binding transport proteins
Describe the role of calcitriol in calcium regulation
- Increases active transport of Ca from gut to blood
- Binds to intracellular receptors in cells that transport calcium i.e. the intestine, kidneys, udder and shell gland
- Also in cells in immune syste,, muscle, endocrine tissue and in bone
- Required for normal functioning of osteoclasts and osteoblasts
- 1-hydroxylase enzyme (catalyses production of calcitriol) stimulates by parathyroid hormone
- Production inhibited by hypercalcemia and hyperphosphatemia
Describe the role of calcitonin in calcium regulation
- Peptide hormone
- Produced in thyroid gland
- Hormone acts to reduce concentration of Ca2+ in extracellular fluid by inhibiting bone resorption and increasing urinary excretion of calcium
- Secretion regulated by concentration of Ca2+ in plasma (not secreted below certain level)
- Increasing levels within normal range leads to linear increase in secretion
- Gastrin, secretin and CCK stimulate calcitonin secretion
- Levels increase after feeding, even when concentration of Ca2+ has not changed
Describe the effect of Ca2+ on parathyroid hormone secretion
- Ca2+ concentration in ECF regulates PTH by direct -ve feedback
- Receptor coupled to G-protein controls exocytosis of PTH-conaining vesicles by second messengers
- Continuously secreted at moderate rate when Ca2+ is in normal range
- Elevated calcitriol in plasma inhibits synthesis and secretion of PTH at given Ca2+ concentration
What is the action of parathyroid hormone in controlling calcium?
- Binding of PTH to membrane receptors increases intracellular concentration of cyclic AMP
- Affects certain enzymes and transport mechanisms
- Increases bone resorption and formation of calcitriol in the kidneys
- Net effect is to increase Ca2+ concentration in ECF
- Rapid and long term effects
What are the rapid actions of parathyroid hormone in calcium control?
- Stimulates osteoblasts and osteocytes to release Ca2+ from bone
- Increases reabsorption of Ca2+ by renal tubular cells adn reduces loss of calcium in urine
- In simple stoamched animals reduces reabsorption of phosphate ions in renal tubules
- Renal excretion of phasphate increases
- Prevents rise in plasma phosphate concentration that would be unfavourable for dissolution of bone mineral crystals
What are the long term actions of parathyroid hormone?
- Changes in bone metabolism and intestinal absorption of calcium
- Mediated via effect of PTH on renal production of calcitriol
- Increased synthesis of calcitriol in the kidneys
- In turn increase intestinal absorption of calcium and phosphate
- Enhanced activity of osteoclasts in bone tissue, both by reruitment of new cells and by increased bone resorption by individual cells
What are the major roles of iron?
- Cytochromes (exploit oxidation and reduction of iron)
- Lots of iron in oxidative phosphorylation
- All of TCA cycle enzymes need iron as a cofactor
- Catalase, peroxidases, phenylalanine hydrolase
Where is iron stored?
- 90% stored combined with proteins
- Haemoglobin
- Transferring (iron transport protein)
- Ferritin (iron storage in liver, spleen, kidney, bone marrow)
Describe iron toxicity
- Not common
- Mainly with prolonged oral administration
- Alimentary disturbances
- Reduced growth
- Induced phosphorous deficiency
In what scenarios is the iron requirement increased?
- Pregnancy
- After prolonged haemorrhage
Describe iron deficiency
- Main symptom anaemia
- Suckling pigs
- Poor appetite adn growth, breathing laboured and spasmodic (thumps)
- Not common in calves or lambs
- Sommetimes in laying hens due to drain of egg production on body reserves
Describe the metabolic roles of manganese
- Major biocehmical role as activator of enzymes including hydrolases and kinases
- Also constituent of arginase, pyruvate carboxylase and Mn superoxide mutase
- Many interactions with choline
- Perosis and fatty liver infiltration
- Choline one of B serous vitamins
Outline the defiency problems associated with manganese
- Ruminants, pigs, poultry
- Retarded growth
- Skeletal abnormalities (muscular weakness, perosis, lameness)
- Ataxia of neonates
- Reproductive failure
- Impaired glucose utilisation
- Reduced vitamin K blood clotting responses
Outline the toxicity problems associated with manganese
- Wide safety margin between requirement and toxic doses
- Not usually an issue
- Depressed appetite
- Reduced growth
Describe the major metabolic roles of zinc
- Essential component of over 200 metalloenzymes
- Carbonic anhydrase, pancreatic carboxylase, alcohol dehydrogenase, alkaline phosphatase, thymidine kinase
- Activator of several enzyme systems
- Cell replication and differentiation (RNA/DNA synthesis)
- Production, storage and secretion of hormones
- Immune system
- Electrolyte balance
Outline the deficiency problems associated with zinc
- Major dietary interaction siwth calcium and phytate
- Also copper
- Pigs fed high Ca rations (incl. phytate)
- Subnormal growth, depressed appetite, poor food conversion and parakeratosis
What are the symptoms of zinc deficiency in calves?
- Inflammation of nose and mouth
- Stiff joints
- Swollen feet
- Parakeratosis
What are the symptoms of zinc deficiency in chicks?
- Retarded growth
- Foot abnormalities
- Frizzled feathers
- Parakeratosis
- Swollen hock syndrome (bone abnormality)
Outline the problems with zinc toxicity
- Most animals have high tolerance
- Depressed good consumption
- May induce copper deficiency
- Zinc usually associated with protein content in diet
Describe the metabolic roles of iodine
- 2 known roles
- Thyroxin
- Triiodothryonin
- Are the thyroid hormones
Describe the roles of the thyroid hormones
- Increase basal metabolic rate
- Accelerate growth
- Increase oxygen consumption
- Control development of foetus
- Involved in immune defence, muscle function, seasonality of reproduction
How are T4 (thyroxin) and T3 (triiodothryonin) produced?
- Iodiine from iodides in blood coombine with tyrosine to produce monoiodotyrosine (T1) and diiodotyrosine (T2)
- 2xT2 condense = T4
- T4 is physiologically inactive transport form stored in thyroid gland
- Released into blood as required
- Converted into active T3 peripherally (mainly kidneys and liver)
What is the importance of selenium in iodine metabolism?
- Deiodinase enzymes (T4 to T3) are selenium dependent
- Deficient in selenium, reduced iodine metabolism
Describe the symptoms of iodine deficiency
- Enlarged thyroid gland (goitre) due to compensatory hypertrophy
- Reproductive abnormalities
- Underweight, hairless, weak or dead offspring
- Cretinism
- Oestrus suppressed/irregular
- Reduced milk yield
- male decreased libido, reduced semen quality
- Poor wool growth
What may cause iodine deficiency?
- Not supplying enough in diet
- High amount of goitrogens (found in brassicas)
- Thiocyanate competitive inhibition of iodine uptake, can be overcome by increased iodine supplementation
- Goitrin inhibits iodination of tyrosine, cannot be overcome by increasing dietary iodine
- High dietary nitrogen inhibits iodine uptake
Outline the problems with iodine toxicity
- Depressed weight gain and feed intake
- Decreased egg production
- No effect on fertility of effs but early embryonic mortality
- Reduced hatchability and delayed hatching
- Pigs more tolerant
Describe the major metabolic roles of molybdenum
- Involved in a few metalloenzymes
- Xanthine oxidase
- Aldehyde oxidase
- Sulphite oxidase
- Cogactor in reaction of xanthine oxidase with cytochrome C
Outline the deficiency problems associated with molybdenum
Has not been observed in any species under natural conditions
Outline the toxicity problems of molybdenum
Interactions with copper
Describe the major metabolic roles of chromium
- Essential for normal glucose utilisation
- Role in lipid synthesis
- Protein and nucleic acid metabolism
- Improves appetite weight gain and humoral immune response in recently moved and vaccinated (stressed) calves
Outline the deficiency and toxicity problems with chromium
Not particularly toxic
Describe the major metabolic roles of lead
No metabolic role
Outline the toxicity probelms associated with lead
- Acute leads to GI haemorrhage, anaemia, kidney damage and liver necrosis
- Chronic leads to osteoporosis, hydronephrosis, loss of appetite and “lead lines”
- Suckling lambs/young calves vulnerable
- Reduced learning
- Often from paint, old batteries, sewage sludge, mining activities
Describe the major metabolic roles of cadmium
No metabolic role
Outline the toxicity problems associated with cadmium
- Highly reactive and toxic
- Antagonistic interactions with copper and zinc (increased zinc decreases Cd absorption)
- Accumulates in liver and kidney
- Sources: superphosphate fertilisers, sewage sludge
- Can lead to decreased appetite, fertility and libido
Describe the major metabolic roles of fluorine
Tooth strength
Outline the deficiency problems associated with fluorine
No natural deficiency in farm animals
Outline the toxicity problems associated with fluorine
- Ruminants more susceptible
- Dental pitting and wear
- Depressed appetite
- Lameness
- Reduced production
- Bone and joint abnormalities
- Sources: fluoride containing water, industrial pollution, use of soft/raw rock phosphate supplements
List the vitamins of the B complex
- Thiamin
- Riboflavin
- Nicotinamide
- Pyridoxine
- Pantothenic acid
- Biotin
- Folic acid
- Choline
- Cyanocobalamin
Describe the vitamine B complex
- All water soluble
- Most components of co-enzymes
- Not stored in tissues
- Regular dietary supply essential
- In ruminants can generally be synthesised by bacteria in rumen
- Also bacteria in gut of horse
- By caecal fermentation
- Ingested through coprophagy in rabbits
Describe the role vitamin B1 - thiamin
- Coenzyme thiamin pyrophosphate
- Oxidative decarboxylation of pyruvate to acetyl CoA (lactate accumulation)
- Oxidative decarboxylation of alpha-ketoglutarate to succinyl CoA in TCA cycle
- Transketolase in pentose phosphate pathway
- Thiamin triphosphate involved in activation of Cl channel in nerve cell membranes
Describe the role vitamin B2 riboflavin
- Flavoproteins
- All involved in transport of H reactions
- Oxidative phosphorylation
- Succinic dehydrogenase (TCA cycle)
Describe nicotinamide
- AKA niacin, nicotinic acid
- Very stable
- Synthesised from tryptophan, low dietary requirement, conversion rates can be low
- Cats need preformed source (cannot synthesise)
- Active group os 2 important co-enzymes
- NAD and NADP
Describe B6 pyridoxine
- Consists of 3 readily interchangeable forms
- Pyridoxine (most stable)
- Pyridoxal
- Pyridoxamine
- Mainly functions as pyridoxal phosphate
- Over 50 of these
- Transamination adn decarboxylations
- Role in absorption of AAs from intestine
Describe pantothenic acid
- Consituent of CoA
- Energy metabolism
- Widely distributed vitamin
- Deficiency rare in practice
Describe the role of biotin
- Prostethic group for 3 important enzymes
- Pyruvate carboxylase
- Acetyl CoA carboxylase
- Proprionyl CoA carboxylase
Describe folic acid
- Converted to tetrahydrofolic acid
- Coenzyme for mobilisation and utilisation of single carbon groups (methyl, formyl) (histidine, serine, glycine, methionine, purines)
- Involved in synthesis of RNA, DNA and neurotrasmitters
- Green leady veg and cereals good natural sources
- stable under dry conditions, degraded by moisture and UV light
Describe choline
- Unlike other B vits not metabolic catalyst/cofactor
- Component of lecithin
- Important role in lipid metablism
- Prevent accumulation of fat by converting excess fat into lecithin
- Increase utilisation of fatty acids
- Component of ACh
- Donor of methyl groups for transmethylation reactions involving B12 or folic acid
- Methionine or betaine can replacce choline as methyl donor but not other functions
Describe B12 cyanocobalamin
- Almost exclusively microbial origin
- Requires specific glycoprotein (intrinsic factor) to bind in intestine for absorption
- Many metabolic roles
- Isomerases, dehydrases, enzymes for synthesis of methione from homocysteine, methylation
- Proprionate metabolism
Describe the deficiency symptoms of B1 thiamin
- Loss of appetite
- Emaciation
- Muscular weakness
- Progressive dysfunction of nervous system
- Widely distributed in foods so deficiencies rare
Describe the deficiency symptoms of B2 riboflavin
- Deficiencies rare in ruminants (synthesised in rumen)
- Loss of ppetite, diarrhoea, lesions in the corners of mouth
- Iin pigs required for normal oestrus activity and prevent premature parturition
- Poor appetite, growth retardation, vomiting, skin eruptions adn eye abnormalities
- In poultry chicks “ curled toe paralysis”, reduced hatchability and embryonic abnormalities
Describe deficiency in nicotinamide
- Ruminal supplementation may reduce ketosis in early lactation
- May be low in maize diets
- In pigs leads to poor growth, anorexia, enteritis, vomiting, dermatitis
- In poultry leads to bone disorders, feathering abnormalities, inflammation of mouth and upper oesophagus
Describe B6 pyridoxine deficiencies
- Results in large variety of biochemical lesions
- Predoominantly related to AA metabolism
- Widespread distribution of pyridoxine in plants so deficiency unlikely
Describe pantothenic acid deficiencies
- Widespread vitamin so deficiency rare
- Some reports in commercial pigs
- Slow growth, diarrhoea, hair loss, scaliness of skin, “goose-stepping” gait
Describe biotin deficiencies
- Widely distributed, availability low in P&P from some feeds incl barley adn what
- In pigs leads to foot lesions, alopecia, dry scaly skin, decreased growth rate, decreased food utilisation, decreased reproductive performance in sows
- In poultry leads to reduced growth, dermatitis, legbone abnormalities, cracked feet, poor feathers, fatty liver and kidney syndrome
Describe folic acid deficiencies
- Chickas and youg turkeyrs
- Poor growth, anaemia, poor bone development, poor egg hatchability
Describe choline deficiencies
- Methionine or betaine can replace choline as methyl donor but not other functions
- Synthesised in liver from methionine
- Exogenous requirement influenced by methionine in diet
- Requirement high
- Deficiency rare
- Can lead to slow growth, fatty infiltration of liver
- Manganese interacts with choline
Describe B12 cyanocobalamin deficiencies
- Adult animals less suscpetible
- Young have growth retardation and high mortality
- In young pigs poor growth, lack of hind leg coordination
- In older pigs dermatitis, rough oat, sub-optimal growth
- In poultry decreased growth, poor feathering, kidney damage, decreased hatchability
- In ruminants related to cobalt, decreased growh, decreased appetite, anaemia, emaciation, pica often exhibted
- In horses linked to cobalt
Explain why ruminants do not need a dietary source of B complex vitamins
- Can be synthesised by bacteria in rumen
- Cobalt required in vit B12 production
Explain how some compounds can act as vitamin antagonists
- Thiaminase
- Antagonist to thiamin
- Present in bracken, raw fish
- bacterial thiaminase may be induced by acidotic conditions in rumen (rapid fermentation)
- Can lead to circling movements, head pressing, blindness, muscular tremors
- In poultry may cause paralysis, stargazing, fatty liver and kidney
Outline cobalt and its interaction with B12
- Needed to produce B12
- Most B12 deficiencies caused by cobalt deficiency initially
- Also has role as activating ion in certain ensyme reactions
- Cobalt poorly retained in animal
- Even if a lot of cobalt provided, will not dramaticaly increases production of B12
- Bacteria need time to adjust to high dose of cobalt
- Some used, some excreted
- Uptake into animal is quick
- Cobalt in blood not useful for B12 production, need slow release source
Why is high cobalt in the blood useful in racehorses?
- Good for oxidative carrying in blood
- Increases stamina
- Is therefore banned in racehorses
List sources of vitamin A
- Fish liver oil
- Egg yolks
- Milk fat
Describe precursors for vitamin A
- Certain carotenoids in plants
- Converted to vit A
- 2 main categories: carotene and xanthophils
- Lots of different xanthophils
- Main vit A source in ruminants is beta carotene
- Different conversion eggicacies in different species
- Cats do not have enzyme to convert carotene to vit A, need dietary source
Where is vitamin A stored?
The liver
What can be used to assess the amount of vitamin A present?
- Serum retinol
- Retinyl ester concentrations
- Liver biopsy
- Clinical signs and diet
List the sources of vitamin C
- Citrus fruits
- Green leafy vegetables
- No precursors
How can vitamin C be synthesised
- From glucose via glucoronic acid and gulonic acid using L-gulonolactone enzyme
- No store of vit C
- Cannot be synthesised by guinea pigs or primates
How can vitamin C status be assessed?
- Low liver and kidney concentrations
- In fish - vertebral collagen level
- Blood tests and x-rays
- Clinical signs (reduced healing etc)
List the sources of vitamin D
- Fish liver oil
- Sundried roughage
- Egg yolk
List the precursors of vitamin D
- Animal derived vitamin D3 (cholecalciferol) or plant derived D2 (ergocalciferol)
- Are precursors for calcittriol
- D3 activated by UV
- Skin vit D (7-hydroxycholesterol)
- Cholecalciferol goes on to form calciferol, which goes on to form active calcitriol
Describe the synthesis of D3
- Humans can synthesise from UV
- Cats and dogs lack enzyme that converts precursor to cholecalciferol so cannot synthesise from UV
- Skin vit D (7-dehydroxycholesterol) converted to D3 using UV
Where is vitamin D stored?
Liver
How can vitamin D status be assessed?
- Measurement of low serum 25(OH)-D3
- Ionised calcium concentrations
- Increased PTH concentration
Describe symptoms of vitamin D deficiency
- Rickets
- Puppies lethargic
- Poor muscle tone, bowing of limbs
- Clinical signs of calcium deficiency in adults (take time to develop)
- Kittens have poor food intake, lose weight, generalised ataxia, caudal paralysis
- Young catle arched back, swollen hocks
- Pigs enlarged joints, broken bones, stiff joints, adversely affected growth rates, occasionally paralysis
- Poultry bones and beak soft and rubbery, legs weak, reduced egg production with poor shell quality
Describe the metabolic role of vitamin A in the eye
- Retinol converted to 11-cis isomer, oxidised to 11-cis-retinaldehyde
- Used to see in the dark
- Combines with opsin to form rhodopsin
- Photoreceptor for light at low light intensities
- Retinal is same as 11-cis-retinaldehyde
Describe the metabolic role of vitamin A in general system
- Regulation of cellular differentiation
- Formation adn protection of epithelial tissues and mucous membranes
- Important in growth, reproduction adn immune response
- Also important in resistance to disease and promotion of healing through its effect on immune system and integrity of epithelium
Describe the symptoms of vitamin A deficiency
- Blindness
- Epithelial infection
- Night blindness
- Roughened hair, scaly skin
- lambsborn weak or dead
- In poultry mortality rate high, retarded growth, ruffled ploumage, staggers
- Dogs: ataxia and anorexia
- cats: reproductive and developmental disorders
Describe the major metabolic roles of vitamin C
- Oxidation reduction mechanisms in living cells
- Cofactor for these
- Needed for maintenance of normal collagen metabolism
- Cofactor for hydroxylation
- Plays role in transport of iron-ions from transferring to ferritin
- Antioxidant, ascorbic acid works with vit E in protecting cells from oxidative damage caused by free radicals
Describe the symptoms of vitamin C deficiency
- Reduced resistance to infection
- Failure in collagen formation - strucural defects
- Wound healing at slower rate
- Those that do not synthesise more at risk
Describe the major metabolic roles of vitamin D
- Similar to steroid
- DNA transcription in microvilli
- Induce synthesis of specific mRNA
- Repsonsible for production of calcium binding protein
- Amount produced by kidney controlled by PTH
- Calciferol increases absorption of phosphorous from intestines
- Enhances calcium and phosphorous reabsorption from the bone
What may predispose a cow to hypomagnesaemia?
- Low magnesium intake
- Older cow
- Ingestion of high levels of potassium and nitrogen (fertiliser)
- Spring calving
- Eating rapidly growing grass
- Consistently stormy wet weather meaning does not eat
- More crude protein in grass disrupting microflora
Explain how magnesium affects calcium metabolism
- Compete for transport mechanism
- Less magnesium means more calcium influx into nerve endings
- Increased release of ACh leading to tetany
- Low magnesium reduces PTH
- More Ca into urine
- Low magnesium => less competition => high calcium => less PTH released leading to decreased resorption from bone, increased excretion in urine
Explain how potassium affects magnesium absorption
- High potasium leads to reduced uptake
- Leads to apical membrane depolarising
- Reduces transepithelial potential
- Does not propel rumen magnesium into blood
Explain how sodium affects magnesium absorption
- Low sodium leads to reduced uptake
- Sodium-linked ATP-ase dependednt transporter
- Low sodium cannot generate concentration gradient
- Sodium not drawn into cell to be pumped out on other side
- As sodium is drawn into cell, magnesium would be taken with it (symport)
Where is magnesium absorbed in the ruminant and non-ruminant?
- Ruminant: rumen
- Non-ruminant: small and large intestine
List some of the important nutritional interactions
- Sodium-potassium
- Calcium-magnesium
- Manganese-iron
- Iron-copper
- Zinc-copper
What may cause a high iron content of forage?
- Acidic soil
- Compacted and anaerobic
- Contamination of crop in harvest time
What are some of the analytical methods available for assessing mineral status?
- Rate/endpoint assays
- Feed testing
What are soe suitable samples for assessment of mineral status?
- Serum and whole blood
- Milk
- Urine
- Post mortem sample of liver
What is serum an appropriate sample to test the status of?
- All macro- and microminerals
What is urine an appropriate sample to test the status of?
P, Cl, Na, Pb
What is the liver an appropriate sample to test the status of?
Fe, Se, B, Mn complex vitamins, Cu
Co by testing levels of B12 in th liver
What is whole blood an appropriate sample to test the status of?
Cl, Mn, Pb Se
Describe the major metabolic roles of selenium
- Mainly incorporated into antioxidant enzyme glutathione peroxidase
- Immune response
- Iodine metabolism
- Metabolism of sulphydral compounds, fatty acids and glucose
- Interacts with vitamin E
How does selenium affect iodine metabolism?
- Deiosinase enzymes are selenium dependent
- Iodothyronine deiodinase is crucial for thyroid function
- Converts thyroxin/T4 inactive form to T3 active form
Describe the major metabolic roles of vitamin E
- Membrane bound antioxidant
- Immune system
- Not stored in the body
- Interactions with selenium
- a,b,x,d - tocopherols (greek letters) - saurated form
- a-tocotrienol also has vitE activity - unsaturated form
Describe the interaction between selenium and vitamin E
- Are mutually replaceable
- Maintains Se in body in active form (GSHPx form)
- Prevents destruction of lipid membranes, inhibiting production of peroxides
- Therefore lowers requirement of GSHPx
Describe the metabolic roles of copper
- Metalloenzymes
- Activator of several enzyme systems
- Development of CNS and heart
- Energy and iron metabolism
- Immune sysem
- Pigment and connective tissue formation
- Antioxidant
List some of the important copper enzymes
- Tyrosinase
- Cytochrome oxidase
- Lysyl oxidase
- Superoxidase dismutase
- Caeruloplasmin
What is the action of tyrosinase?
Conversion of amino acid tyrosine to black pigment melanin
What is the action of cytochrome oxidase
Electron transfer chain (reduces energy utilisation)
What is the action of lysyl oxidase
- Collagen adn elastin cross linkage
What is the action of superoxidase dismutase
Antioxidant and immune function
What is the action of caeruloplasmin
Blood copper transport system and oxidant of Fe II to Fe III for incorporation into haem
Describe the metabolic role of magnesium
- Close metabolic associations with Ca and Phos
- 70% in skeleton, rest highly metabolically active
- Most common enzyme converter
- FOrmation of cyclic AMP
- Cellular respiration, forms complexes with ATP, ADP and AMP
- Moderate neuromuscular activity
Describe deficiencies in magnesium
- Many species
- Depleted bone magnesium, tetany, death
- Main problems are in ruminants (hypomagnesium tetany/grass staggers)
- In ruminants major absorption from rumen decreased by potassium
What are the symptoms of selenium deficiency?
- White muscle disease
- Ill thrift, reduced groth rates, decreased wool
- Impaired immune function
- Decreased reproductive performance
- In pigs: mulberry heart, hepatosis dietetica
- In poultry: pectoral myopathy, encephalomacia, exudative diathesis, pancreatic fibrosis
- Stiff but weak
What are the symptoms of selenium toxicity?
- Alkali disease, blind stagger
- Fullness, lack of vitality, rough coat, hair loss, soreness/sloughing of hooves
- Stiffness/lameness, sudden death
- Areas of high Se or Se accumulator plants can cause this
How can selenium in the body be assessed?
- Blood Se
- GSHPx
Describe the symptoms of vitamin E deficiency in pigs
- Muscular myopathy
- Mulberry heart disease
Describe the symptoms of vitamin E deficiency in poultry
- Mainly pectoral myopathy
- Encephalomacia
- Exudative diathesis
Describe the symtoms of vitamin E deficienc in the horse
- Lameness and muscle rigidity from muscle myopathy
- Red blood cell fragility
- Myoglobin release to urine (coffee colour)
Describe the symptoms of copper deficiency in non-ruminants
- Rare in non-ruminants
- Copper related anaemia can occur when milk only diet
- Older animals deficiency unlikely
- In cats leads to poor reproductive performance, kittens small, weak, discoloured and curly coats
Describe the symptoms of copper toxicity in non-ruminants
- Cumulative poison
- Pigs highly tolerant
- Can lead to growth retardation
- Haemolytic crisis not as pronounced
- In poultry can lead to erosion of gizzard
Outline the deficiency problems associated with copper in ruminants
- Swayback
- Hair/wool keratinisation and depigmentation
- Bone disorders
- Anaemia
- Infertility
- Immune function impaired
- Lipid metabolism and oxidative stress
- Impaired glucose metabolism
- Lots of processes in rumen, interactions leading to deficiency
- Thiomolybdate toxicity leads to copper deficiency
Describe how thiomolybdate toxicity leads to copper deficiency
- Mo (molbdenum) binds to sulphide
- If does not bind to copper, absorbed into tissues from rumen as MoS
- Copper in an enzyme, MoS binds, changes shape of enzyme, action prevented by altering active site
- More sulphur in MoS, more affinity for copper
- In intestine, Cu, Fe form complex, insoluble, passedin urine
- CuMoS4 passed in urine
- Copper lock up, not absorbed
- Cu absorbed into tisues
- MoO4 (molybdate) absorbed into tissues, will not bind to Cu
- If copper and thiomolybdate are absorbed separately then bind, affects enzyme activity
- CuMoS4 and Cu can go to the liver
Outline the toxicity problems associated with copper in ruminants
- Mainly problem if over or inappropriate copper supplementation
- Copper toxicity itself not reported to affect reproduction
- Long term thiomolybdate treatment of copper toxicity does cause infertility
- Se supplementation in sheep and goats predisposes to increased risk of copper toxicity
- Copper loaded in liver, need stress trigger togo from copper loaded to copper toxic
What are the signs of copper toxicity in ruminants
- Weak
- Tremulous
- Listless
- Anorexic
- Haemolytic crisis breakdwon of haemoglobin into urine and plasma
Describe the diagnosis of copper toxicity and deficiency in ruminants
- Liver enzymes AST, GGT
- Liver already damaged when these rise!
Describe the treatment of copper toxicity in ruminants
- Injection of ammonium tetrathiomolybdate (not recommended!)
- Zinc therapy
- Feeding of other antagonists
- Iron, molybdenum, zinc
How is sheep breed linked to copper deficiency/toxicity?
- Depending on breed predisposed to deficiency/toxiciy
- Historical location
- Lots of copper naturally present = more likely to be deficient
- Not much copper present = more likely to become toxic
- Swaledale, scottish blackface, charollais deficient
- Suffolk, texel, bluefaced leicester usually no problems
- North ronaldsey toxic (eat seawweed, seaweed low in copper)
How can the macromineral status of an animal be assessed?
- Serum levels (not always accurate, levels homeostatically regulated)
- Feed
- Urine
How can the trace mineral status of an animal be assessed?
- Feed
- Serum, plasma, whole blood (no homeostatic regulation!)
- Functional indicators (enzymes, vitamins, cobalt for B12)
- Milk (not great, changes in “cycle”)
How can the vitamin status of an animal be assessed?
- Not many tests available
- Mainly B12, sometimes B1
- Assess functional indicators
- Don’t tend to get deficiencies, may be expensive
How can copper status of an animal be assessed?
- Plasma copper up, function down
- PLasma copper, TCA solube copper, caeruloplasmin superoxide dismutase haemoglobin/haematocrit
How can vitamins and minerals be supplemented
- Bolus (slow release)
- Free access lick (nt always effective)
- In feed
- Added to water
- Injection
- Liquid drench
- Use of certain fertilisers
- Changing crops
Describe chelates
- A compound containing a ligand (typically organic) bonded to a central metal atom at 2 or more points
- Some minerals bound to proteins of enzymes, others present in prosthetic groups in chelated form
- E.g. chlorophylls, cytochromes, haemoglobins, vitamin B12
