Mag, Potassium, Vit D

What is the least bioavailable magnesium form?

Magnesium Oxide (MgO)

What is the most bioavailable magnesium form?

Magnesium Amino Acid Chelate

Magnesium is an important cation needed by both ____ and _____.

plants, animals

Magnesium is contained in chlorophyll as a “____”

chelate

How much magnesium is found in bone?

50-60%

_____ and ____ have marked effect upon Mg requirements.

Calcium and phosphorus

Increasing Ca and/or P ____ the Mg requirement.

increases

_____ can act as an antagonist towards Mg.

Potassium

As potassium increases, what must happen to Mg to meet requirements?

add more Mg

What vitamin promotes the absorption of Mg into the body and enhances absorption and retention of Mg into cells?

B6

What are the functions of Mg?

1. Bone development

2. Blood pressure regulation

3. Enzymatic activity

4. Metabolism (protein, fat, carbs)

5. Muscle contraction/relaxation

6. Synthesis of RNA, DNA, glutathione

---

____ is needed for all phosphate transfers

Magnesium

Oxidative phosporylation to ATP

In some reactions ___ may replace Mg as an enzyme activator

Mn

Mg is an activator for all enzymatic reactions requiring ____

TPP (thiamine pyrophosphate)

Mg is a ___ for many enzymes in the body.

cofactor

Explain Mg role in acid-base balance

• Mg salts must be in ionic form before they can be absorbed

• Stomach acids are able to break down bonds holding Mg to other molecules

• Mg flows to mineral ion channel along intestinal wall

• Mg cannot be absorbed in other molecules are attached bc ion channel is so small

• Will therefore be excreted as waste

Name the Mg deficiency symptoms

• Anorexia

• Muscle spasms (grass tetany)

• Calcium deposits

• Hyperirritability

• Skin lesions

• Reduced productivity

• Reduced fermentation in rumen and cecum

• Retracted head in calves

• Death

____ need a constant source of Mg through diet due to not being able to access and utilize the stores within their bones and muscle.

Cattle

High ___ rations will aggravate deficiency symptoms and increase the dietary need

Calcium

Cattle fed milk rations may exhibit:

• convulsions

• tetany

• irritability

Absorption from forages ranges up to 40% depending on ________.

the soil

Grass tetany is due to

low magnesium

What is most at risk for grass tetany?

older cows with calves as well as over/underweight cattle

Grass tetany occurs on what pastures?

heavily fertilized with N and/or K followed by rapid growth

Why does grass tetany occur on heavily fertilized pastures?

Elevated nitrates and potassium act as antagonists and reduce magnesium absorption

____ have lower levels of magnesium than legumes.

cool season grasses

What are the initial signs of grass tetany?

Nervous apprehension

Head held high

Staring eyes

Stilted staggering gait

Muscle twitching

What are the final clinical signs of grass tetany?

Extreme excitement

violent convulsions

coma

death

What are preventative measures for grass tetany?

Mineral lick tubs with Mg (opti-lix)

Feed mg addition

What are the therapeutic grass tetany treatments?

IM injection Mg sulfate

Mg enema

Magnesium can also be used as a _____

laxative

Potassium is frequently referred to as

Potash

Largest industrial use for Potassium is _____

fertilizer

What are the functions of Potassium?

1. Osmotic balance

2. Maintains acid-base balance

3. Muscle activity (Na/K pump)

4. Carb digestion

How is KCl used in euthanasia?

leads to cardiac arrest

What is K’s role in muscle contraction?

Na: higher in extracellular

K: higher in intracellular

Na moves against concentration gradient to induce impulse then muscle contraction occurs in response

Why do muscle cramps occur?

low K levels

cramp occurs when K leaves the cell

K pills help elevate K levels and stop cramps

Where does absorption of K occur?

1. SI (upper SI)

2. Rumen (reticulo-rumen) via simple diffusion

How effective is Na, K absorption via simple diffusion?

>90%

How is excess K primarily excreted?

urine

Explain the Na/K pump

• Moves ions across the plasma membrane in opposite directions

• Pumps 3 Na ions out of the cell for every 2 K ions pumped in

• Energy dependent

Why might K deficiencies occur?

• low dietary intake (if on high grain diet)

• excessive loss due to diarrhea or vomiting

• High Na intake and > urination (increase K loss)

• Heat stress

• forage K loss due to being rained on

Symptoms of K deficiency

• Reduced feed consumption

• Reduced growth

• Muscle weakness

• Diarrhea

• Rough hair coat

Hard to diagnose by looking at animal

Excessive KCl can cause death due to

reduced heart rate

enhanced respiratory movements

abnormal heart rhythm

Vitamin did is a _ soluble vitamin

fat

Known as the sunshine vitamin

Vit D

Vitamin D is not required by animals with ___ ___

sunlight exposure

Vitamin D is also known as the ___ ___ hormone

calcium homeostasis

Natural Sources of Vit D

D3 and D2

Primary functions of Vit D3

Increase intestinal Ca absorption

Ca mobilization

Ca retention

Bone deposition of Ca and P

We need what form of Vit D

D3

You need ___ for Vit D absorption

fat

Pioneers in research of Vit D

Lund and DeLuca

D2 & D3 circulate in blood in __ concentration

low

Main compound form of D3

1, 25

1, 25 (OH)2 D3 - have hormonal functions in intestine and bone hydroxylase activated regulated by:

calcitonin, PTH in response to serum Ca & P concertation

Deficiency in vit D takes a ___ amount of time due to low vit d turnover for D within skin & fat tissue.

fair

_ tissue stores the most vit D throughout the body

Adipose

Excretion of vit D is primarily in the

feces

Factors that influence vit d requirements

Ca to P ratio

Light skin

As age increases skin thickness, synthesis decreases Ca and P availability

Deficiency symptoms of Vit D

Rickets

Weak bones w/ bending

Enlarged hock & knee joints

Tendency to drag hind legs

Beaded ribs

__ toxicity may cause vit D deficiency as it impairs the kidney 1,25 hydroxylase

Pb

Vit D deficiency in ruminants

Lower appetite and growth rate

Stiffness in gait

Labored breathing

Lower Ca (occasional tetany and convulsions)

Vit D deficiency Swine

Lower appetite and growth

paralysis

fractures

Vit D deficiency Poultry

Rickets in young chicks

Assume squatting position

thin shells

Assessment of Vit D deficiency

X-ray show lack of Ca deposition

Low serum Ca

Higher alkaline phosphatase

Low circulating 25 (OH)2 D

Vit D toxicity - hypervitaminosis D

D3 is more toxic than D2

Toxic symptoms related to increased serum Ca due to high bone resorption and intestinal absorption

Pathological effects of Vit D toxicity

soft tissue calcification

inflammation

cellular degeneration

bone thinning

Plants high in Vit D - can cause toxicity

Solanum melanoxylon - shrub (Argentine and Brazil)

Trisetum flavescens - Grass (Europe)

__ have high sensitivity to Vit D

Rodents

Treatment to Vit D toxicity

Withdraw vit D - low Ca diet