The Most important metabolic troubles of Peripartuient Dairy cows and their prevention (hypocalcaemia)

Question 1

Milk fever also known as

Answer 1

parturient paresis
Usually subclinical (over clinical)

Question 2

What is the function if PTH and when is it inhibited

Answer 2

Calcium mobilization from the bone, resorption from the gut and kidney tubules. Active vit D from the kidney stim the gut resorption
High CAB inhibits it!! this is often the case during dry cows last 2 weeks when they are given an alkaline daily ration i.e high CAB (usually high K or high Ca

Question 3

Milk fever and age

Answer 3

Increased risk with older! The second or third lactation requires more milk, therefore more ca but the animal is less capable of mobilizing from the bone, transporting in the intestine and producing active vit D

Question 4

Which breed are prone to milk fever?

Answer 4

Jersey cattle!!
They have higher milk prod but smaller size, therefore fewer vit D receptors and therefore a decr ability to absorb calcium

Question 5

What is the CAB and what mechanisms add to it?

Answer 5

Cation Anion balance
From dietary organic/inorganic sources
Carbonic acid: CO2+H20—- H2CO3— HCO3- and H+
1. aerobic ox of carbs
2. ox of anions e.g malate, citrate and fumarate
3. anionic aa’s e.g glutamate
4. ox of aa’s: meth, cys, lys (are these the sulphur containing ones?)
5. anaerobic metab of glucose produing lactic acid
6. Cations e.g NH4+

Question 6

CAB formula and units

Answer 6

(Na+K)-(Cl+SO4) in mEq/kg DM

If positive: then increased risk of milk fever vs negative

Question 7

Dietary K content

Answer 7

Higher risk of causing milk fever than high dietary Ca
Sources: legumes e.g alflafa and fertilizers that increase the K content of the plants!!
K inhibits Mg uptake– and the PTH requires Mg

Question 8

Preventing a high CAB via the diet

Answer 8

Acidifier salt supplementation– NH4Cl (consists of weak base and strong acid)
No realrecommended amount- can use 3 mol but note the more you add, the more bitter the feed and therefore decr palatibility and DMI
For high yield dairy cows during last 2 weeks of lactation
Note: compensated metab acidosis- the urinary pH will be 6.2-6.8

Question 9

What is the CAB optimal range

Answer 9

(-50)-(-150) mEq/kg DM

Question 10

When do you lower the CAB

Answer 10

For close off period
Last 2 weeks of dry period
When finished calving

Question 11

When do you give vit D treatment

Answer 11

10 days before calving, and if calving was prolonged then repeat the treatment