Metabolic Diseases of Ruminants: Minerals

Question 1

What is released when ECF Ca is low?

ECF: Extracellular fluid

Answer 1

PTH

Parathyroid hormone

Question 2

What mineral is required to release PTH from parathyroid cells?

Answer 2

Mg

Magnesium

Question 3

What is the purpose of Vitamin D?

Answer 3

Helps mobilize bone mineral and increases absorption of Ca and P from gut

Question 4

What is released when ECF Ca is high?

Answer 4

Calcitonin

Question 5

What muscle types does hypocalcemia affect?

Answer 5

All types of muscles!
* Skeletal
* Smooth
* Cardiac

Question 6

What role does calcium play in the CNS?

Answer 6

• Ca is needed for neurotransmitter release in the brain
• Low Ca in ECF can result in coma
• Ca is needed for insulin release (glucose regulation)
• Low Ca can result in hyperglycemia

Question 7

What are the other names for “milk fever”?

Answer 7

• Periparturient paresis
• Hypocalcemia

Question 8

Milk fever is primarily a ____ disease

Answer 8

Dairy cow

Question 9

When does milk fever usually occur?

Answer 9

Within 48 hours after calving

Body temperature does not increase in animals with hypocalcemia

Question 10

What are some predisposing factors of milk fever?

Answer 10

• Heavy milk production (10x the ECF Ca content required at onset of lactation
• Older cows (not as responsive to PTH and Vitmin D)
• Failure of hormonal systems to keep up with Ca loss into colostrum and milk

Question 11

What are the 3 stages of milk fever?

Clinical Signs

Answer 11

• Stage 1: Standing, irritable, tremors
• Stage 2: Recubent and depressed
• Stage 3: Lateral recumbency, coma

Most often recognized in stage 2

Question 12

What is treatment for milk fever?

Answer 12

• Ca borogluconate (IV or SQ
• Oral calcium gels

Question 13

What can be done to prevent milk fever?

Answer 13

• Feed anionic salts prior to calving
  1. Cow’s blood becomes more acidic
  2. Ca stores in the body are mobilized
  3. Make sure ration has enough Mg

Question 14

T/F: There is a hormone system to closely regulate Mg

Answer 14

False

There is NO hormone system to closely regulate Mg

Question 15

What is the purpose of Mg?

Answer 15

• Co factor to hundreds of enzyme systesms (carbohydrates, protein, lipid metabolism)
• Influences membrane properties (opposes/ competes with Ca at neuromuscular junction to allow for muscle to relax)

Question 16

In adult ruminants, where is Mg primarily absorbed?

Answer 16

Rumen

Question 17

In calves, where is Mg primarily absorbed?

Answer 17

Small intestines

Question 18

Is Mg absorption efficient in the GI tract?

Answer 18

No, not very efficient 7-35% of ingested

Question 19

What plays a critical role in Mg absorption?

Answer 19

• Feed and soil factors
• High N and K in ration affect Mg absorption

Question 20

What are clinical signs of hypomagnesemia?

Answer 20

• Hyperexcitable
• Aggressive
• Twitch
• Tremor
• Bellow
• Lateral recumbency
• Convulsions
• Death from respiratory arrest

Question 21

What are hypomagnesemia sydromes?

Answer 21

• Grass tetany
• Wheat pasture poisoning
• Winter tetany
• Transport tetany
• Milk tetany

Question 22

Grass tetany

Answer 22

• Rapid growing grasses (spring or fall)
• Heavily fertilized areas (N and K in fertilizers)

Question 23

Wheat pasture poisoning

Answer 23

Cereal crops low in Mg (eastern CO, KS, OK)

Question 24

Winter tetany

Answer 24

• Mg deficient forages during cold months

Question 25

Transport tetany

Answer 25

• Stress and low Mg diets
• Catecholamines moves Mg into cells

Question 26

Milk tetany

Answer 26

• Whole milk or milk replacer fed to growing calves without access to higher Mg feeds

Question 27

T/F: relapses of hypomagnesemia are common

Answer 27

True