Macrominerals

Question 1

Are macrominerals large in size?

Answer 1

NO

Question 2

What is hypomagnesia also known as?

Answer 2

Grass staggers

Grass tetany

Question 3

Why does hypomagnesia arise?

Answer 3

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

Question 4

What are the clinical signs associated with grass staggers?

Answer 4

• 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

Question 5

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

Answer 5

Vitrium of the eye

Question 6

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

Answer 6

Red cows

Question 7

How is hypomag treated?

Answer 7

Urgently!

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

Question 8

Where should you stand by a downer cow?

Answer 8

Behind the back

Question 9

How may hypomagnesium be prevented?

Answer 9

Mg alone not v palatable

• MgO mix with molasses
• Mg bolus orally precalving
• Mg in drinking water
• Avoid K fertiliser (pig manure)

Question 10

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

Answer 10

Blue cows

Question 11

What is hypocalcaemia also known as?

Answer 11

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

Question 12

What are the normal levels of calcium in the blood?

Answer 12

2.3 - 3.2 mmol/l

Question 13

Outline Ca homeostasis

Answer 13

• 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

Question 14

What are the clinical signs associated with subclinical hypocalcamiea?

Answer 14

• 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

Question 15

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

Answer 15

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

Question 16

What are the clinical signs associated with severe clinical hypocalcaemia?

Answer 16

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

Question 17

What is the treatment for milk fever hypocalcaemia@?

Answer 17

• 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)

Question 18

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

Answer 18

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

Question 19

What is the cause of hypocalcaemia?

Answer 19

• 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)

Question 20

Which cows are at risk of milk fever?

Answer 20

• older
• fatter
• channel breeds

Question 21

How may hypocalcaemia be prevented?

Answer 21

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

Question 22

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

Answer 22

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

Question 23

What may cause v phosphorus?

Answer 23

^ Ca soil

Question 24

How is hypophosphatemia treated?

Answer 24

Foston I/v

Question 25

What is DCAB?

Answer 25

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

Question 26

What are the cations?

Answer 26

Na and K

Question 27

What are the anions?

Answer 27

Cl and S

Question 28

What units are anions and cations analysed in?

Answer 28

mmol/kg DM

Question 29

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

Answer 29

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

Question 30

What should be monitored when using the DCAB diet?

Answer 30

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