B5: Rumen Acidosis. B6: Ketosis, B7: Hypocalcemia

Question 1

Rumen acidosis. Types

Answer 1

1. Subclinical
2. Clinical

Question 2

Rumen acidosis. Causes

Answer 2

• excess concentrates (RAC - readily available CHs: starch, sugars) in 1st phase of lactation —> increase of propionic acid —> drop of pH —> lactic acid increases (pH≤5,5)
• amount of saliva decreased —> buffering decreased

Question 3

Normal pH of rumen

Answer 3

6,2 - 6,8

Question 4

Rumen acidosis. Symptoms

Answer 4

• decrease of appetite
• rumen atony, bloat
• diarrhoea (osmotic, caused by lactic acid)
• lactic acidemia
• metabolic acidosis
• laminitis
• liver abscesses

Question 5

Rumen acidosis. Prevention

Answer 5

• fibre supply — minimum 18% of DM
• buffers (sodium bicarbonate, magnesium oxide)
• sufficient concentrates feeding close to calving (2-4 kg) to adapt microflora to huge amount of starch given PP

Question 6

Ketosis. Definition. What’s behind ketosis?

Answer 6

• production of ketone bodies > usage of ketone bodies
• ketone bodies can be found in blood, urine, milk (5:10:1)
• negative energy balance in first 8 weeks PP -> fat mobilisation -> increase of FAs level -> end product of FAs metabolism is acetyl-coenzyme A but it can’t enter Krebs cycle because oxaloacetae is missing because it is involved into GNG to maintain blood glucose level for milk fat production, lactose production and ovarian function -> acetyl CoA is transformed into ketone bodies

Question 7

Consequences of high ketone bodies concentration

Answer 7

• ketonuria —> energy loss —> NEB is worsened
• acidosis
• reduced performance, milk production and fertility

Question 8

How does the BCS of cows influence the incidence of ketosis?

Answer 8

Ketosis type 1: BCS ≤ 3-3,5 (undernutrition)
- can develop 3-6 weeks PP

Ketosis type 2: BCS > 3-3,5 (fatty cow syndrome)
- can develop 1-2 weeks PP
- more common than type 1

In both cases hypoglycemia
In case of type 2 will lead to insulin resistance —> hyperglycemia —> hypoglycemia (reduced appetite)

Fat cow —> higher leptin —> inhibition of neuroleptide Y release —> reduced food intake —> NEB

Question 9

How to prevent ketosis ?

Answer 9

• feeding management of dry cows !!!
• keep them on maintenance level (feeding intensity = 1)

To reduce NEB:
- by-pass sugar
- by-pass fat (hot pressed rapeseed cake, heat-treated full fat soya, propylene glycol, glycerol, by-pass AAs)

Question 10

Control of ketosis

Answer 10

Based on milk and urinary ketone bodies

Question 11

Hypocalcemia. Types

Answer 11

1. Subclinical (more common)
2. Clinical (milk fever)

Question 12

Consequences of hypocalcemia

Answer 12

• inhibition of muscle function
• NEB
• displaced abomasum
• decreased milk yield
• metritis
• dystocia

Question 13

What’s behind the hypocalcemia?

Answer 13

• LACTATION
• insufficient PTH activity !!!
• last 2 weeks before parturition cows get alkaline daily ration (high value of CAB (cation-anion balance) caused by high K) (WHY WOULD WE DO THIS IF IT INCREASES CHANCE OF HYPOCALCEMIA LATER???)
• due to high CAB value after calving the PTH activity is limited —> calcium can’t be mobilised from the bones; also can’t be absorbed from GI because of lower vit D level and calcium reabsorption from urinary tract is also inhibited —> hypocalcemia

Question 14

How to prevent the hypocalcemia?

Answer 14

• goal: to reduce CAB
• acidic diet: ammonium chloride, magnesium sulphate

Question 15

Milk urea level

Answer 15

• (MUN - milk urea nitrogen)
• this concept reflects protein to energy ratio in the ration
• optimum: 3,5 - 6 mmol/l

Question 16

What causes elevation of milk urea level?

Answer 16

Because it reflects protein to energy ratio in the ration, elevation of milk urea level is caused by either
- increased protein in the ration (excess RDP)
- decreased energy in the energy (low RAC (readily available CHs)
- in 1st lactation phase it’s the most important because it’s the time of rebreeding in the end of the 1st phase —> milk urea level can be associated with fertility. If milk urea level is higher than optimum, fertility is declined (lowered pH in vagina and uterus)

Question 17

Diagnosis based on ketone bodies

Answer 17

• individual measurement, result reflects the energy status of milking group
• BHB is measured commonly (beta-hydroxybutyrate), also aceto-acetic acid, acetone

Question 18

Ketonuric index

Answer 18

• concentration of ketone bodies is measured (Rothera-test for urine -> becomes purple 0-4/5 scale )
• interval from the calving must be known as well

Determination: 10 x result of rothera test +- 2 x days from calving (before calving - positive, after - negative)

If result is > 20-25 —> energy status of a cow must be improved !!