Herd level metabolic disease Flashcards
Which diseases are important at a herd level?
Ketosis and negative energy balance (NEB)
Hypocalcaemia (milk fever)
Why does ketosis matter?
How can negative energy balance be monitored?
What BCS should be aimed for at different periods to reduce the likelihood of ketosis?
Key targets…
- 2.5-3 at calving
- no change during dry period (maintain BC)
- maximum 0.5 drop calving –> peak lactation
- avoid cows >3 at calving
Each cow should get a BCS calving and at peak lactation.
How can metabolic profiles be used to monitor ketosis?
- Blood sampling a random group of cows
- At specific stages
- Usually transition cows and fresh calvers
- (21-7 days pre-calving) (10-25 DIM)
- Indicators of negative energy balance…
- At specific stages
-
BHB
- Ketone body
- Indicates current energy supply/demand
- Esp. important in fresh calvers
-
NEFA
- Transport form of fat
- Indicates mobilisation of body fat
- Esp. important in transition cows
- Metabolic profiling:
-
How many samples?
- Varies with size of group (e.g. dry cows)
- BUT not that much!
- Typically 8-12 samples/group required
- Interpreting results
- Target prevalence of high BHB/NEFA generally <10-20%
- Usually this means any abnormal results are potentially suggestive of a problem
- Typically >=3/12 high considered “positive”
How can milk parameters be used to measure ketosis?
In neg energy balance the milk protein content tends to go down
Butterfat concentration tends to go up
How can ration analysis be used to monitor ketosis?
- Ration analysis
- Estimate feed intake and ration energy density
- Compare to cow energy requirements
- Specialist software available
How is negative energy balance caused with regards ration at early/peak lactation (type 1) compared to transition/calving (type 2)?
How much DMI should 700kg holstein cow get?
- Aiming for… (700kg Holstein cow)
- >23kg DM/day at peak lactation
- >12kg DM/day in transition (late dry) period as approaches calving intake drops off
- 23kg is DRY MATTER intake for the day (could easily be 60kg fresh weight!)
What are the ‘sticking plaster’ solutions to ketosis?
Dietary additives that may improve the situation…
- Propylene glycol (alternative glucose source)
- Protected methionine (improves export of fat from liver)
- Linoleic acid (fatty acid with less tendency to accumulate in liver)
- Monensin (antibiotic, changes balance of rumen microflora increases propionate:acetate)
- Available as rumen bolus in UK
- Licensed for use in “cow/heifer which is expected to develop ketosis”
What is a word of warning with making a ration more energy dense with concentrate?
One way to make it more energy dense is to replace with concentrate but be careful as it may push rumen into SARA (acidosis)
SARA: subacute ruminal acidosis
How does hypocalcaemia occur?
- Sudden increase in demand at calving (lactation)
- If stores (mainly bone) not mobilised quickly enough…
- Circulating [Ca] falls
- Clinical or subclinical “milk fever”
Draw a schematic for calcium mobilisation?
How does a drop in plasma calcium cause the problems observed with milk fever?
How can hypocalcaemia be diagnosed?
- Clinical signs
- Blood sample (¯plasma [Ca])
What is a DCAB diet and how does it prevent milk fever?
- Dietary cation-anion balance (DCAB)
- Difference between levels of major cations (Na+, K+) and anions (Cl-, S2-) in diet
DCAB = ([Na+] + [K+]) – ([Cl-] + [S2-])
(all in mEq/kg DM)
- Diets with low DCAB (<0mEq/kg DM) induce mild metabolic acidosis…
- Metabolic acidosis means…
- More vitamin D3 is activated per unit PTH
- Target tissues (esp bone) are more sensitive to PTH and 1,25(OH)2D3
- So the cow is more able to mobilise Ca from body reserves quickly
What is a partial DCAB approach and how is it achieved?
- “Partial” DCAB approach
- Manipulate available feeds to decrease ration DCAB to around 0 to +100 mEq/kgDM
- +/- small amount anionic salt
