11.3.5: LDAs at herd level

Question 1

Describe how dietary change can lead to LDAs

Answer 1

• Ruminal papillae grow and shrink according to how many VFAs are being produced
• VFAs are the cow’s source of energy and are produced by fermentation of organic matter in the rumen
• If there is a sudden switch from low to high concentrate diet then VFAs will not be fully absorbed by the ruminal papillae (which only have a small surface area)
• This means VFAs reach the abomasum
• This is thought to decrease abomasal motility and therefore enable an LDA

Question 2

This diapgram shows the possible pathway to decreased abomasal motility, which can lead to an LDA.
What are 1-6?

Answer 2

Question 2

1

Answer 2

Question 3

2

Answer 3

Question 4

3

Answer 4

Question 5

4

Answer 5

Question 6

What are the physiological consequences of a displaced abomasum and what should you do about them?

Answer 6

Just rehydrate the cow after fixing the DA and these issues will solve themselves.

Question 7

Which other organ in the abdomen can become kinked when the abomasum is displaced and what should you do about it?

Answer 7

The duodenum - this is sorted when the displaced abomasum is replaced to its normal position

Question 9

Risk factors for displaced abomasum

Answer 9

• Subclinical ketosis
• Subclinical milk fever
• Overconditioned at calving
• Parturition
• Sudden changes in diet / breaking into feed store / dump feeding
• Previous displaced abomasum that was managed conservatively and not fixed into place
• Pain
• Retained foetal membranes -> metritis
• High production herd / being a Holstein
• Reduced DMI around calving
• A low fibre diet

Question 10

Why is a low fibre diet a risk for DA?

Answer 10

• Low fibre diet -> moves through rumen much quicker than high fibre diet
• This means even if the cow is eating a sensible amount of food, the rumen is not full
• Decreased rumen fill -> more space in abdomen -> LDA

Question 11

What is the ideal BCS at calving?

Answer 11

2.5-3

Question 12

Prevention of displaced abomasum

Answer 12

• Maximise DMI around calving / early lactation
• Appropriate BCS at calving
• Transition diet: some but not too much concentrate, sufficient long fibre
• Fresh calved diet: sufficient long fibre
• Early lactation: energy balance is key
• Check milk fever control and if high incidence of clinical cases - cause of this needs addressing
• Check incidences of other diseases e.g. metritis and association with LDA cases

Question 13

1-4

Answer 13

Question 14

How much condition (in terms of condition scores) is acceptable for a cow to lose from calving to early lactation? When might there be a problem?

Answer 14

• Cow should lose max. 0.5 of condition score
• If several are losing much more than this, they might be calving in at too high a condition (i.e. over 3) and there could be issues with NEB / ketosis

Question 15

A low yielding, block calving herd has suddenly had 5 LDAs. Previously, they have not had any. There has been no change in the amount of concentrates fed in the parlour. The cows are calving in at appropriate BCS. The farmer does not experience problems with ketosis or metritis. The cows are calving in from Feb-April. They are at grass for calving and the whole grazing system.

What could be the cause of their recent LDAs?

Answer 15

• Likely subclinical milk fever (farmer not aware of clinical cases)
• Potassium levels of grass varies throughout the year and this can in turn impact calcium
• Because the cows are grazing they are very vulnerable to this
• In this system where cows are under less pressure than high yielding herds, we can see clusters of DAs precipitated by poor weather and changes in grass quality