Monitoring Nutrition

Question 1

Which diseases are we trying to avoid?

Answer 1

• ketosis and negative energy balance
• milk fever

Question 2

When are cows at risk?

Answer 2

• following calving, hard to increase feed intake fast enough to supply lactation energy
• in peak lactation

Question 3

What consequences can negative energy balance have?

Answer 3

• decreased fertility
• impaired immune function
  
  • metritis/RFM
  • mastitis
• role in other diseases
  
  • LDA
• reduced milk quality

Question 4

How can you use body condition scoring to monitor energy balance?

Answer 4

• no change oevr dry period
• max decrease of 0.5 between calving and peal lactation
• aim for 2.5-3 at calving, esp avoid>3

Question 5

When would you run metabolic profiles? What do they monitor? What results are you looking for?

Answer 5

Usually “transition” cows (e.g. 21-7d pre-calving)… and fresh calvers (e.g. 10-25 days in milk)
Key indicators of energy balance are…
BHB (beta-hydroxy butyrate)
* Ketone body
* Current energy supply/demand
* Esp useful in fresh calvers
NEFA (non-esterified fatty acids)
* Transport form of fat
* Indicator of fat mobilisation
* Esp useful for transition

Results
* Target prevalence of high BHB or NEFA <10-20%
* Usually means any abnormal results suggest a problem!
* >=3/12 abnormal results taken to indicate herd problem

Question 6

What are the rough targets for DMI in high yielding cows and transition cows?

Answer 6

Question 7

How can you improve dry matter intake?

Answer 7

• minimise (impact of) group changes
• easy access, trough space per cow
• avoid over conditioned cows (especially at calving)
• maximise ration palatability
• manage environment appropriately (temp, humidity, comfort)

Question 8

What additives can we include to increase dry matter intake?

Answer 8

• Propylene glycol
• Protected methionine
  
  • Improves fat export from liver
• Linoleic acid
  
  • Fatty acid with less tendency to accumulate in liver
• Monensin
  
  • Antibiotic, changes rumen flora to aid energy balance - bolus for “at risk” cows

Question 9

How can we diagnose clinical and subclinical milk fever?

Answer 9

Clinical milk fever
* Characteristic clinical signs
* Blood sample shows low plasma Ca

Subclinical milk fever
* Much more difficult!
* Control restored within 2-3d of calving
* Can monitor…
◦ Clinical case rate - <5 cases/ 100 cows/ year is a common target
◦ Using blood samples within 24-48hrs of calving
◦ Urine macrominerals

Question 10

How can we prevent milk fever?

Answer 10

• Diets with low DCAB (<0 mEq/kg DM) induce mild metabolic acidosis…
  
  • …metabolic acidosis means
    ◦ Enhanced uptake of Ca from the GI tract
    ◦ Ca mobilisation from bone
    ◦ Higher rate of vitamin D3 activation per unit PTH
    ◦ Increased target tissue sensitivity to PTH and activated vit D3
  • So the cow is able to mobilise Ca from body reserves more quickly
• Ca restriction
  
  • “Conditions” homeostatic mechanisms to be more efficient at Ca uptake/mobilisation
  • Hard to get diet [Ca] low enough with normal feeds
  • Ca binding feedstuffs available
    ◦ Work well but moderate cost
    ◦ Becoming popular in UK
• Mg supplementation
  ◦ Mg required for production of PTH
  ◦ Generally not very effective alone
• Prophylactic treatment
  ◦ Ca boluses most appropriate
  ◦ Often targeted e.g. at older cows

Question 11

What are the 2 types of DCAB diets?

Answer 11

True or full DCAB
* Aim for diet DCAB around -100 mEq/kg DM
* Likely to require use of anionic salts (e.g. MgCl2, MgSO4)
* Usually needs Ca supplementation too
* Effective but more involved/ expensive

Partial DCAB
* Aim for diet DCAB around 0 to -50 mEq/kg DM
* Often just by choosing lower DCAB feeds, may also use salts
* Usually doesn’t require Ca supplementation
* More common in lower yielding herds