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Are macrominerals large in size?



What is hypomagnesia also known as?

Grass staggers
Grass tetany


Why does hypomagnesia arise?

- No homeostatic mechanism for controlling Mg levels (cf. Ca)
- deficiency arises when ^ demand v intake


What are the clinical signs associated with grass staggers?

- range peracute to subclin
- hyperaesthesia
- twitchy ears
- sensitive to sound/hand clap
- staggers, collapses - signs of thrashing and struggle
- jaw champing
- sudden death
- ^ HR
> subclin
- slow onset 3-4d
- spasmodic urination/defeacation
- mm tremor
- staggering gait
- ^ HR
- usually post-partum so difficult to distinguish normal urogenital pain


What sample may be analysed by the lab post-mortem to ID hypomag?

Vitrium of the eye


What are hypomag cows reffered to as?? (By van winden )

Red cows


How is hypomag treated?

- Bottle Ca borogluconate with Mg hypophosphate I/V slowly
- Magnesium sulphate 25% s/c only (IC -> Cardiac arrest)


Where should you stand by a downer cow?

Behind the back


How may hypomagnesium be prevented?

Mg alone not v palatable
- MgO mix with molasses
- Mg bolus orally precalving
- Mg in drinking water
- Avoid K fertiliser (pig manure)


What are hypocalcaemic cows reffered to as?? (By van winden)

Blue cows


What is hypocalcaemia also known as?

- Bovine parturient paresis
- Hypocalcaemia
- Acute flaccid paralysis
- Milk fever


What are the normal levels of calcium in the blood?

2.3 - 3.2 mmol/l


Outline Ca homeostasis

- Absorbed in GIT, kidney and bone
- PTH regulates
- Vit D3 converted in kidney and activated in liver works on GIT ONLY to ^ absorbtion
- Calcitonin binds free Ca (low clinical impact)
- Mg co-factor required to activate D3, produce/release PTH and other stages


What are the clinical signs associated with subclinical hypocalcamiea?

- able to stand
- hypersenstivie
- excitable
- tremors
- ears twitching
- ataxia
- bloat or gas in gut [sm mm affected first]
- slowed gut transit
- v VFI
> Blood Ca: 1.8-2.3


What are the clinical signs associated with moderate clinical milk fever?

- recumbent (sternal)
- depressed
- dry muzzle
- cold extremities
- bloat
- no defeacation (on rectal = full)
- delayed/absent pupil responses
> Blood Ca: 1.2 - 1.8


What are the clinical signs associated with severe clinical hypocalcaemia?

- reduced consciousness
- lateral recumbency
- unresponsive
- mm flaccidity
- v CO
- bloat
- death
> Blood Ca <1.2


What is the treatment for milk fever hypocalcaemia@?

- 20% Ca Borogluconate 400ml
> Higher conc available but unneccesary, may -> hyperCa -> depressed PTH etc. -> yoyo between hypo hyper
- low volume tx maxacal 100ml
- some may have mg, p , glucose mixed in
> Inject SLOW i/v and monitor HR - may -> cardiac arrest
- sc deposit to prevent reoccurrence (usually to tide over until fresh food available)


How can you tell an animal is recovering from milk fever?

- sits up (may need assistance)
- defeacates
- eructates


What is the cause of hypocalcaemia?

- demand not met by supply
- absorption from KIDNEY
- GIT: dry cow ration too ^ in Ca -> v % absorption
- feed intake in fat cows may be inadequate
- BONE reserves low in old cows
> amount of Ca available in each reserve inversely proportional to speed it can be released (ie. kidney small amount quickly, bone large amount slowly)


Which cows are at risk of milk fever?

- older
- fatter
- channel breeds


How may hypocalcaemia be prevented?

- LOW Ca in dry cow ration
- High Ca milking cow ration
- Supplement Mg
- DCAB diet
- drench or bolus around calving


How are hypo-phosphoraemic cows described? How may this be identified?

- "Happy downer"
- Mg/Ca Tx doesn't work
NB: Make sure to check for other casues of being down - Fx, toxic, neuro problems etc.)


What may cause v phosphorus?

^ Ca soil


How is hypophosphatemia treated?

Foston I/v


What is DCAB?

Dietary cation anion balance
- Cations subtract anions should = v pH blood
- allows PTH to be more effective and optimised Mg absorption
> achieved by v K in diet and ^ anions


What are the cations?

Na and K


What are the anions?

Cl and S


What units are anions and cations analysed in?

mmol/kg DM


Give examples of anions that can be fed in the diet. What are potential down sides to using these?

Magnesium chloride
Magnesium sulphate
Calcium chloride
Ammonium chloride
-> unpalatable and may v DMI -> NEB, fatty liver, metabolic issues


What should be monitored when using the DCAB diet?

Urine pH of several cows each week
- aim for 5.5-6.5
- NO LOWER THAN 5.0-5.5 (too many anions being absorbed)
- aim for small range between cows so you know the diet is being well spread throughout the herd