Mineral & Vitamin Metabolism

Question 1

What is selenium?

Answer 1

Trace element
Essential for normal cellular function
Cofactor for reduction of antioxidant enzymes
Cofactor for thyroid hormones deiodinases
Removes reactive oxygen species & controls metabolic rate

Question 2

What are some causes of pregnancy toxaemia (twin lamb disease)?

Answer 2

Poor rationing during late pregnancy - often related to poor metabolic energy (ME) silage
Outdoor sheep in poor weather conditions
Ketosis
Twin pregnancy

Question 3

What are some signs of pregnancy toxaemia (twin lamb disease)?

Answer 3

Disinclination to move (stupidity)
Ketone bodies
Disturbed bodies
Constipated
Recumbency & death

Question 4

What are some treatments for pregnancy toxaemia?

Answer 4

Dextrose (intravenous bolus)
Propylene glycol & glycerol drench
Glucocorticoids

Question 5

How can you prevent pregnancy toxaemia (twin lamb disease)?

Answer 5

Ensure good quality nutrition in the last 8 weeks of pregnancy
Supplement rations with hay/silage or concentrate

Question 6

What are some causes of hypomagnesaemia (grass staggers/tetany)?

Answer 6

Fresh lush pasture is low in magnesium
Fertiliser (N or K) can reduce uptake of Mg into pasture (K locks Mg in soil)
First cut silage can be low in Mg (<0.2% DM)
Usually during lactation

Question 7

What are some signs of hypomagnesaemia (grass staggers/tetany)?

Answer 7

<0.8mmol/L blood = subclinical
Hyper-excitable frothing at the mouth
Muscle twitching & teeth grinding
Dead stock at pasture

Question 8

How can hypomagnesaemia (grass staggers/tetany) be treated?

Answer 8

Animal should not be stimulated
Mg sulphate administered SC
Hay treated with 60g of Mg oxide daily

Question 9

How can hypomagnesaemia (grass staggers/tetany) be prevented?

Answer 9

2.5g/kg DM of Mg for lactating cows at pasture
Soil assessment regarding K & Mg levels
Herbage may be dusted with powdered Mg oxide (500g/cow) or sprayed with a 2% solution of Mg sulphate
Mineral licks or slow release boluses on known troubled swards

Question 10

What are some causes of Cerebrocortical Necrosis (CCN) (polioencephalomalacia (PEM))?

Answer 10

Vitamin B1 (thiamine) deficiency, caused by:
-rapid changes in plane of nutrition (poor to high quality), which leads to subclinical lactic acidosis, and hence an alteration in ruminal microflora reducing production of B1
-destruction of B1 within the rumen/GIT
(thiaminases - bracken fern or produced by gut bacteria)
-sulphur excess

Question 11

What are the signs of Cerebrocortical Necrosis (CCN) (polioencephalomalacia (PEM))?

Answer 11

Nervous system disease resulting in necrosis of the brain
Circle, blindness, convulsions, collapse, leg-kicking & death

Question 12

How can Cerebrocortical Necrosis (CCN) (polioencephalomalacia (PEM)) be treated?

Answer 12

Early administration of thiamine may be curative
(if lesions are more advanced, surviving animals may remain partially blind & mentally dull)

Question 13

How can Cerebrocortical Necrosis (CCN) (polioencephalomalacia (PEM)) be prevented?

Answer 13

Diet formulation to ensure no SARA
Prophylactic administration of vitamins
Check bracken levels in fields
Check possible fonts of S excess

Question 14

What are some causes of swayback?

Answer 14

Low ewe blood copper (Cu) levels, resulting in underdevelopment of the myelin sheaths in lambs
Low Cu uptake or usually poor absorption due to formation of copper thiomolybdate (CuMoS4)

Question 15

How can swayback be treated?

Answer 15

No cure

Question 16

How can swayback be prevented?

Answer 16

CoSeCure boluses
Supplementation with copper oxide (ensure not to cause Cu toxicity - sheep accumulate Cu in liver)
Assess Cu, Mo & S levels of sward & soil (higher Mo levels in legumes)

Question 17

What are some causes of pine?

Answer 17

Lack of cobalt (Co) + inability to manufacture Vitamin B12 in the rumen
(vitamin B12 = 250-500pg/mL blood)

Question 18

What are some signs of pine?

Answer 18

Loss of appetite
Unthrifty
Dull
Dry fleeces
Emaciation & death

Question 19

How can pine be treated?

Answer 19

Vitamin B12 IM injection
Drenching up to 1mg/kg bw of cobalt sulphate

Question 20

How can pine be prevented?

Answer 20

CoSeCure boluses or cobalt bullets
Co status of farm (swards & soil)

Question 21

What are some causes of white muscle disease (nutritional muscular dystrophy)?

Answer 21

See & vitamin E deficiency (cellular antioxidants)
Bioavailability of inorganic Se is poor
S levels influence the incorporation of Se into organic forms on pasture

Question 22

What are some signs of white muscle disease?

Answer 22

Acute & rapid wasting of skeletal muscle, despite a good appetite
Unable to stand - heart muscle damaged + stiff limbs
Death

Question 23

How can white muscle disease be treated?

Answer 23

IM or SC injection of young lambs with 0.75-1.5mg Selenium as potassium selenate + 34-68 vitamin E

Question 24

How can white muscle disease be prevented?

Answer 24

Supplementation of dam’s ration during late gestation
Injection of all new born lambs
CoSeCure bolus or Sel-Plex (Seleno-methionine)

Question 25

What causes aphosphorous?

Answer 25

Phosphorus deficiency due to poor diet or grazing arid soils low in P

Question 26

What are some signs of aphosphorosis?

Answer 26

Question 27

How can aphosphorosis be treated?

Answer 27

Question 28

How can aphosphorosis be prevented?

Answer 28

Adequate diet rationing & P fertiliser of depleted soils
Phosphorus concentration of 0.42% DM is adequate for high-yielding dairy cows

Question 29

What causes vitamin A deficiency?

Answer 29

Deficiency in vitamin A
Poor/no access to pasture & badly formulated rations

Question 30

What are the signs of vitamin A deficiency?

Answer 30

Night blindness
Impaired immunity
Infertility
Roughened coat & scaly skin
Very weak/dead lambs
Xerophthalmia (eyes - dryness, ulceration & copious lacrimation)
Sperm production damaged in bulls