ANS 124: Proteins in Milk

What happens if you ultracentrifuge the Milk Fat Globules?

The membrane of the milk fat globules fall off and gather on the bottom of the test tube.

Why can infants digest milk?

Because they make lactase in the gut.

With age, why does lactose intolerance occur? (even though as an infant, you can digest milk)

The promoter for lactase becomes deactivated with age.

In a person that is NOT lactose intolerant, what happens to Lactose in the small intestine?

Lactose breaks down into glucose & galactose and is absorbed.

In a person that IS lactose intolerant, what happens to Lactose in the small intestine?

Lactose stays in the gut and is not broken down.

What are the 2 things that can happen when Lactose stays in the gut and isn't broken down?

Lactose draws water into the gut, causing watery feces/diarrhea.

The presence of lactose causes microbial growth. The microbes release H2 in the blood.

What is one way we can detect for Lactose Intolerance in the blood or feces?

By detecting H2 from blood or feces.

Is Lactose Intolerance the same as an allergy to cow's milk?

No, it is distinct from each other.

Lactose Intolerance can exist as what 3 different "forms"? (what can cause it?)

Lactase Activity Decreases with Age

Gut Damage, Post Surgery, etc.

Genetic Mutation = No Lactase Activity

What is the most common reason for Lactose Intolerance?

Lactase Activity Decreases with Age

What is an uncommon reason for Lactose Intolerance?

Genetic Mutation = No Lactase Activity

What are the 3 symptoms of Lactose Intolerance?

Diarrhea

Bloating

Gas

The symptoms of Lactose Intolerance happen how many hours after milk ingestion?

0.5 to 2 hours after milk ingestion

What are 3 ways to test for Lactose Intolerance?

Lactose Tolerance Test

Measure dissolved hydrogen levels in breath.

Stool pH, for babies, acidity indicates lactic acid presence.

What happens in a Lactose Intolerance Test?

Pre-test fasting, then ingest pure lactose (dissolved) and measure glucose levels.

What can people with Lactose Intolerance take to reduce it's effects/symptoms?

can take Lactaid, which is lactase enzyme in pill

How have some dairy companies modified milk to cater to people with Lactose Intolerance?

Some dairy companies filter out lactose in milk.

Is Lactose a sweet sugar?

No, it is not a very sweet sugar.

If Sucrose is 100% sweet, what is Lactose and Fructose on that scale?

Lactose = 16%

Fructose = 173%

What are the 6 Proteins in Milk?

Immunoglobulins

The Caseins

α-Lactalbumin

β-Lactoglobulin

Proteins in the Milk Fat Globule Membrane

Other Whey Proteins

Immunoglobulins are primarily in ______________.

colostrum

How do the different forms of caseins work together?

they work together in order to suspend as micelles in liquid section of the milk

What are the 2 main whey proteins?

α-Lactalbumin

β-Lactoglobulin

β-Lactoglobulin is only found in the milk of what animals?

Only in ruminants.

Why are there proteins in the Milk Fat Globule Membrane?

The membrane is from the apical cell wall that wraps around it during pinocytosis. There are proteins in that membrane.

What are the 2 proteins in the Milk Fat Globule Membrane?

Xanthine Oxidase

Butyrophilin

What are 5 other Whey Proteins that depends on the health & species of the animal?

Albumin (from blood)

Many different Growth Factors & Low-Level Proteins

Lysozyme

Lactoferrin

Species Specific Proteins

What is the most abundant protein in blood?

Albumin

What is the purpose of Albumin in blood?

it is a carrier protein for things like fat

Why would Albumin be found in the whey of milk?

If Tight Junctions are leaky or if alveoli is damaged, then blood protein albumin will be found in milk.

What is the hypothesis for why there are many different Growth Factors in milk?

To help the health of the neonate since growth factors can help with the development of cells.

Lysozyme is important in _________ milk. (what species)

human

Lysozyme and Lactoferrin are both what?

antimicrobials

Why are antimicrobials like Lysozyme and Lactoferrin found as whey proteins in milk?

Because the milk is at risk of mastitis/infection and the body wants to make sure that infants don't get sick.

What is a whey protein that is found in the milk of pigs and rodents?

Whey Acidic Protein

Is Whey Acidic Protein found in cow and human milk?

No, it is only found in pig and rodent milk.

What is a Whey Protein that is found in marsupial milk?

They have additional "Late Lactation Proteins"

Colostrum is thick because of what?

Because it has high concentrations of antibodies.

What is the color of colostrum?

yellow

Colostrum is high in what? (besides antibodies)

fat

Why is colostrum stored at dairy farms and at colostrum banks for humans?

to make sure there is high quality colostrum available when needed

In a study looking at human babies born prematurely, how did giving a dose of high quality colostrum to the baby affect cost?

For every baby given a dose of colostrum, it saved a LOT of money.

Can you buy bovine colostrum on Amazon?

yes

If you buy bovine colostrum off of Amazon and drink it, would it be useful? Explain why.

It would not be useful to us because the immune system between a cow and human is different. Also, we can't absorb Ig (protein) whole. It would break down to AAs.

What happens to colostrum [Ig] as we select for dairy cows with higher milk yield?

Colostrum [Ig] goes down as milk yield increases because more milk dilutes Ig.

Describe how colostrum of humans varies in different parts of the world and what contributes to that.

Colostrum varies in Ig composition as people have different immunity to different diseases depending on location. People also receive different immunizations.

In a study that looked at [Ig] in milk in induced lactation cows, what was [Ig] when starting the hormone injections to induce lactation?

[Ig] was low

After the hormone injections to induce lactation were given, what happened to [Ig]?

[Ig] increases

In a study that looked at [Ig] in milk in induced lactation cows, when was [Ig] the highest?

Right before milking started.

In a study that looked at [Ig] in milk in induced lactation cows, what happened to [Ig] after milking started? Why?

[Ig] of milk declines rapidly since the immunoglobulins are all flushed out with the first milk (as colostrum).

Immunoglobulins end up in milk through what type of transport?

transcellular transport

Does Immunoglobulin composition of colostrum differ by species?

Yes

For sheep, cow, pigs (livestock animals) and horses, their colostrum contains a majority of what immunoglobulin?

IgG

For humans, our colostrum contains a majority of what 2 immunoglobulins?

Mostly IgA

...and also some IgM

In humans, immune cells travel from where to secrete IgA and IgM into the milk?

immune cells originating in the gut travel to mammary gland to secrete IgA and IgM into the milk

Compare the amount of immunoglobulins in colostrum between humans vs. livestock.

Livestock have more.

In a study that looked at colostrum [Ig] in cows, what was the cutoff for what was considered high quality or 'good' colostrum?

>50 mg/mL [Ig]

In a study that looked at colostrum [Ig] in cows, describe the distribution of the [Ig] data.

There is a variation between cows for how much Ig is in their colostrum.

In a study that looked at colostrum [Ig] in cows, were there cows that had <50 mg/mL [Ig]?

Yes

In a study that looked at colostrum [Ig] in cows, what needed to be done with the calves of the cows that had <50 mg/mL [Ig]?

They needed to get high quality colostrum that is stored in the freezer on the farm.

In a study that looked at whether passive transfer was successful in calves, what did they measure? Through what method?

measure [IgG] in blood sample with ELISA

In a study that looked at whether passive transfer was successful in calves, what was the cut off for if the calves have successful passive transfer?

10 mg/mL cut off for successful passive transfer

In a study that looked at whether passive transfer was successful in calves, were there some calves below the 10 mg/mL cut-off?

Yes, these calves had failed passive transfer.

For the calves that didn't have successful passive transfer, they are at a greater risk of what 2 things happening in later life?

Greater risk of dying and developing disease.

In CA, the fate of a bull calf in the dairy industry before was what?

Bull calves were by-products of the dairy industry. They weren't worth much (not much meat), and were culled.

In recent years, how has advanced technology helped with the reduction of bull calves in the dairy industry?

A lot more sexed semen is being used so most calves are female.

In the dairy industry, why would we want to ensure good passive transfer happens for female calves?

Because we might want to keep the heifer later in the dairy herd.

What is "Beef on Dairy"?

When a Holstein is crossed with an Angus so that the calf can enter beef industry.

For Holstein x Angus crosses, do we care about whether the calf is male or female? Explain.

No, because a bull calf can be for beef and a heifer calf can be for dairy. (all calves are important and kept for a purpose)

How has HPAI impacted the ability of cows to produce milk?

Cows that got infected do not produce milk when they calf.

What happens to the cows that can't produce milk after getting infected with HPAI?

They are culled.

Since the cows are culled after being infected with HPAI, what has happened to the number of heifers?

we have a shortage of heifers right now

How does the shortage of heifers affect the value of dairy calves? What do we want to ensure in these dairy calves?

Dairy calves now worth a lot more with the shortage going on, and we want to ensure good passive transfer.

Overall, in cow's milk, what is the percentage of milk that is protein?

3.2%

The percentage of protein in milk varies by ________ in cows.

breed

Holsteins have ___% protein in milk.

3%

Jerseys have ___% protein in milk.

4%

The majority of the proteins in milk is ________.

caseins

~___% of protein in cows milk is Caseins.

~80%

What are the 4 forms of Casein in milk?

αS1-Casein

β-Casein

κ-Casein

αS2-Casein

Describe the % of the 4 casein forms that make up total Casein in milk.

αS1-Casein = 38.1%

β-Casein = 35.7%

κ-Casein = 12.8%

αS2-Casein = 10.2%

What is Humanized Breast Milk Substitute?

Infant Formula

Is infant formula based off human or cows milk?

it is based off cows milk

(make it similar to human's milk to create infant formula)

Compare the amount of protein between cow vs. human milk (general).

Cow's milk has a lot more protein than human milk.

What is done to the amount of proteins to make infant formula? Compare the amount of protein in formula vs. cow/human milk.

Take proteins from cow's milk out to try to make it more similar to human milk.

Infant formula proteins are more than human milk and less than cow's milk.

Compare the amount of caseins between cow vs. human milk (general).

Cow's milk has a LOT of casein. Humans have a lot lower casein content in milk.

What is done to the amount of caseins to make infant formula? Compare the amount of caseins in formula vs. cow/human milk.

Reduce Caseins.

Infant formula caseins are more than human milk and less than cow's milk.

What does cow's milk have that human milk does not have?

β-Lactoglobulin (only ruminants make it!)

Do we take out β-Lactoglobulin in infant formula? Why or why not?

No, because it costs a lot to get rid of it.

A supply of what to the mammary gland is critical for milk protein synthesis?

supply of amino acids