Unit 6 -- Part 2
Metabolic Diseases
S. Kenyon

METABOLIC DISEASES

• Pre-partum: fetal growth
• Post-partum: milk production
• Defects of energy, protein or mineral metabolism
• Energy:
  • sheep: pregnancy toxemia (twin lamb disease)
  • beef cattle: protein-calorie malnutrition
  • dairy cows: ketosis
  • horses: lipidemia in fat ponies
• Protein: high levels soluble protein
• Minerals:
  • dairy cow: milk fever

NORMAL ENERGY METABOLISM

• Dairy cows cannot meet energy requirements in early lactation from diet
• In negative energy balance in early lactation
• Mobilize fat and lose weight in 1st 30 days lactation
• begin to restore fat reserves after peak milk (after ~100 DIM)

TOO THIN

• poor peak milk production
• poor lactation persistency
• extended post-partum anestrus
• poor colostrum production and calf growth (beef cattle)
• underfeeding ketosis (production ketosis, primary ketosis)

TOO FAT

• fatty liver
• ketosis
• (pregnancy toxemia - especially ewes)
• fat cow syndrome
• calving difficulties
• milk fat depression

KETOSIS

• Results from:
  • decreased energy supply
  • increase demand for glucose
  • utilization of body fat as energy
• Detectable in milk, urine and on breath

CLASSIFICATION OF KETOSIS

• alimentary
• starvation
• production (primary)
• secondary

PRODUCTION KETOSIS

Negative energy balance > low blood glucose

Low blood glucose > decreased insulin concentrations

Low insulin > high glucagon:insulin ratio and high somatotropin concentration

High G:I ratio and somatotropin > fat mobilization

Fat mobilization > high serum nonessential fatty acids, B hydroxybutyrate

KETOSIS : CLINICAL PICTURE

WASTING FORM & NERVOUS FORM

• Wasting form:
  • normal TPR
  • grain refusal, then silage but eats hay
  • progressive decline in milk production
  • depression
  • loss of condition
  • ketones detectable
• Nervous form
  • depression
  • delirium (episodic), but no convulsions
  • excessive salivation
  • excessive licking
  • head pressing
  • hyperesthesia

DIFFERENTIAL DIAGNOSIS

• Traumatic reticulitis
• Pyelonephritis
• Displaced abomasum
• Secondary ketosis due to above conditions
  • metritis
  • mastitis
• Vagal indigestion

KETOSIS: TREATMENT

• 500ML 50% dextrose i/v
• Propylene glycol ( ~300ml)
• (Ionophore antibiotics - currently illegal)
• Glucocorticoids (dexamethasone 10mg)
  • increases glucose levels through repartitioning
  • suppresses milk production
• Vitamin B12
• Niacin (anti-lipolytic)

PREVENTION

• Ensure correct body condition
• Do not overfeed in dry period
• Adequate good quality fiber and energy levels
• Adequate protein, but not over 16-18%
• Exercise
• (propylene glycol, monensin [illegal], niacin, BST?)

PREGNANCY TOXEMIA OF SHEEP

• Twin Lamb Disease
• Late pregnancy, multiple fetuses, lack of exercise
• Two types:
  • starvation preg.toxemia
  • fat ewe pregnancy toxemia
• May be recent history of exertion, stress
• similar to nervous ketosis in cattle
  • blindness
  • head pressing, lapping
  • constipation & drowsiness
  • recumbency in 3-4 days
• Difficult to differentiate from hypocalcemia/hypomagnesemia
• Propylene glycol
• Drench every 6 hours with oral rehydration soln.
• Immediate supplemental feeding of rest of flock
• Cesarean section

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