ADVS 4200 Lactation

How does cooling cows during the dry period affect their calves?

Calves will grow faster, larger, and provide more milk upon 1st lactation

What is an adaptation that camels have in their milk secretion?

Can change water/salt content of their milk depending on the needs of their young; This depends on their location (arid/fertile)

Cell division, secretion, and cell death ______ occur in one cell at the same time, but all _____ occur within one mammary gland at the same time.

Cannot; Can

Annular Ring (Mammary gland)

Cartilaginous ring between Gland Cistern and Teat Cistern

What are the 3 activities that mammary glands can carry out?

Cell division (DNA) Cell secretory activity (RNA) Cell death (apoptosis)

What does it mean to say that cells develop polarity or a sense of orientation before milk secretion?

Cells understand that they should push milk from the blood side into the lumen

What is Stromal tissue in the mammary gland?

Connective/adipose tissue

Prolactin can be used as a sort of _______ due to its suppressive effects on FSH and LH.

Contraceptive (not 100%)

Organs are ______ to help supply nutrients to the mammary glands.

Coordinated

What are the 3 "standard" milking animals in Utah?

Cow, goat, sheep

What animals mentioned around the world are milked?

Cow, goat, sheep, horse, water buffalo, camel

Anastomosis

Cross-connection between mammary glands

Which produce higher levels of Placental Lactogen, Dairy or Beef?

Dairy

Cold will (Increase/Decrease) Prolactin release.

Decrease

Heat stress on lactating cows can ______ milk production and intake.

Decrease

Short day lengths will (Increase/Decrease) Prolactin release.

Decrease

How do mammary cells affect Progesterone (and iodine) during the 2nd stage of Lactogenesis?

Decrease progesterone by sequestering and metabolizing it within the mammary gland. Progesterone will bind to glucocorticoid receptors, so this will free those receptors to help with final differentiation of mammary cells and for protein synthesis.

Increased production leads to ______ duration of estrus.

Decreased

In placental mammals, all mammary glands are _______ of each other.

Dependent

During the 2nd stage of Lactogenesis, cells are _______.

Differentiating (into secretory cells)

During the 1st stage of Lactogenesis, cells are ______.

Dividing

What is the milk block that is released upon Prolactin release?

Dopamine

The more ______ per teat on an animal, the more difficult it is to treat ______. Why?

Ducts; Mastitis; More difficult to place in correct, affected duct to deliver antibiotics

Why is there more secretory tissue present in the mammary gland at the 2nd lactation rather than the 1st?

During the 1st lactation the cow is still growing and the energy is going more into her own growth than to mammary growth for her calf. During the 2nd lactation she is fully grown and can put more energy to increasing her secretory tissue for the calf.

When does the most mammary gland growth occur?

During the animal's 1st pregnancy

When does major mammary gland development end?

End of gestation

Galactopoietic

Enhancement of an established lactation; Very difficult to do; Only Growth Hormone (GH)

The cellular component of mammary gland development from the mammary bud is controlled by what hormone?

Estrogen

What is the hormone(s) of the 2nd stage of Lactogenesis?

Estrogen, Progesterone, Cortisol, PGF2α, Prolactin (parturition hormones)

What does post-pubertal mammary growth change alongside?

Estrous cycle changes

How does nutrition affect mammary growth around puberty?

Excess fat will be detrimental and cause less milk production, while increased protein will not hinder milk production

The same hormones required for fetal ______ give final ______ to mammary cells during the 2nd stage of Lactogenesis.

Expulsion; Differentiation

The mammary gland is considered a (Internal/External) structure.

External (to the body cavity)

Prolactin can depress the secretion of what 2 hormones? What will this cause?

FSH, LH; Lactational Anestrous

A dry period (rest) between lactations is NOT necessary. (TRUE/FALSE)

False; Dry period between lactations is ABSOLUTELY necessary

The number and location of mammary buds is set by the time you know what?

Female is pregnant (43 days)

What amount of mammary gland development would a castrated male fetus have postpartum?

Female mammary gland development

Concentrations of Placental Lactogen appear to be proportional to number of ______.

Fetuses

Increased production requires more ______ estrus detection or synchronization.

Frequent

Most milk in goats is held in the ______ ______.

Gland Cistern

By GH's repartitioning of fats to the mammary gland, what fat component increases? What is its use?

Glycerol; Used to make lactose

Fat pads are ______ during fetal development. Why?

Good; Give place for mammary gland development

The 1st stage of Lactogenesis is a ______, long process.

Gradual

What factor can significantly (more than genetics) increase a calve's milk yield upon 1st lactation?

Greater Average Daily Gain (ADG) of calf (accounts for 22% of variation)

What is the 1 thing that actually has a glactopoietic effect?

Growth Hormone

What hormone increases blood flow to mammary gland? Why?

Growth Hormone; Increases nutrients available to synthesize milk

Weight is important in mammary growth around puberty, but what form of ______ is more important.

Growth; Protein much more important than fat

Placental Lactogen is secreted in surprisingly ______ levels for a hormone.

High

Alveoli

Hollow ball of single layered cells which secrete milk into Milk Ducts

Humans are extremely difficult to treat for mastitis. Why?

Humans have many ducts per teat (19-20)

There are no pain sensors ___ the mammary tissue

In

Long day lengths will (Increase/Decrease) Prolactin release.

Increase

What is the most important factor in milk secretion?

Increase in mammary blood flow

What is Prolactin's effect on mRNA?

Increase mRNA Increase mRNA transcription Increase mRNA half-life Increase mRNA translation rate

How is mammary gland cell division measured?

Increased DNA

How is mammary gland cell secretory activity measured?

Increased RNA (protein synthesis)

Increased milk production is associated with ______ ovulation rate. Is this good or bad?

Increased; Bad due to "twinning"

Lactogenesis

Initiation of copious milk synthesis and secretion

Lactogenic

Initiation of milk secretion

What was the old method of measuring Prolactin?

Inject cow's blood into pigeon, and the weight of its crop was proportional to the Prolactin levels

What specific adaptation is present in marsupials over placental mammals discussed in lecture?

Joeys will stay attached to the same teat for the entirety of their external development until weaned. That specific mammary gland will produce the correct milk volume and composition for that joey, which may be different from that being produced by the mammary gland adjacent to it. (all mammary glands independent of each other)

The protein α-lactalbumin (Alac), besides being used to measure the presence of tight junctions in alveoli, is part of an enzyme complex that creates ______.

Lactose

What is IGF-I's origin?

Liver

How does photoperiod affect mammary growth around puberty?

Long days increase mammary growth by increasing prolactin

Sensory receptors on the cow's ______ send signals for fight or flight response which constrict smooth ______ muscle of the udder blocking milk.

Lumbar; Sphincter

What structure initially forms into the mammary gland?

Mammary bud

How does the mammary bud become the mammary gland?

Mammary bud burrows into the skin and forms a hard core. This solid core then hollows out and continues branching and hollowing to create the ducts of the mammary gland.

If you don't milk a non-pregnant cow, what will happen to her mammary glands?

Mammary gland cells begin to break down and involute

Isometric Growth

Mammary gland grows at the same rate as the body; Occurs Pre and Post Puberty

Allometric Growth

Mammary gland grows faster than the rest of the body, about 3.5 times faster; Occurs during puberty

Each mammary bud will become what structures?

Mammary gland including streak canal and duct system

Most milk in cows is held in the ______ ______.

Milk ducts

What is Ductal tissue in the mammary gland?

Milk ducts

What is Secretory tissue in the mammary gland?

Milk-producing cells

The release of Prolactin ______ milk production levels.

Mirrors; Both increase in early lactation and decrease as lactation progresses

Why are mitochondria numbers increased before milk secretion?

Mitochondria will produce high amounts of energy for high-energy process of lactation

Cooled cow in dry period produce ______ than heat stressed cows in dry period.

More

Head stress in a dry cow affects both the ______ and the ______.

Mother; Fetus

What is the "pump" that pumps Na+ back into the blood and K+ into the lumen? What is important about its energy consumption?

Na+/K+ ATPase; Requires the most ATP in the lactation process

What amount of mammary gland development would a castrated female fetus have postpartum?

No change to normal female development, due to lack of testosterone anyways

At birth, what is the development status of the mammary gland?

Not developed deep into the skin; Very superficial

What determines the number and location of future mammary glands in a developing fetus?

Number and location of mammary bud

What factor is closely related to growth/production and Growth Hormone?

Nutrition; If nutrition is good then GH response will be better leading to better production/growth. If nutrition is poor then there will be a poor GH response.

Streak Canal

Outer opening of the teat

What hormone causes Myoepithelial cells to contract around Mammary Gland Alveoli?

Oxytocin

What hormone causes milk let-down?

Oxytocin

Concentrations of Placental Lactogen increase as ______ size increases.

Placental

What is the hormone(s) of the 1st stage of Lactogenesis?

Placental Lactogen

Photoperiod affect on mammary growth has its greatest affect in what life stage of the calf?

Pre-puberty

______ during lactation will decrease milk production. Why?

Pregnancy; Mother's energy needs will go towards fetal growth rather than newborn (month 5 of gestation for cattle)

As udder ______ or alveoli become full, secretion rate goes ______.

Pressure; Down

What does Allometric growth occur?

Primarily due to Estrogen, Progesterone, Prolactin

The ductal component of mammary gland development from the mammary bud is controlled by what hormone?

Progesterone

What stimulates Na+/K+ ATPase?

Prolactin

Placental Lactogen can bind to what 2 receptors?

Prolactin, Growth Hormone (GH)

Prolactin regulates ______ synthesis with glucocorticoids.

Protein

What kind of hormone is Prolactin?

Protein

Growth Hormone is a ______ hormone.

Protein (can't be feed in diet because it will denature in stomach)

Placental Lactogen

Protein hormone of the 1st stage of Lactogenesis; Produced by binucleate giant cells from trophoblast cells; Stimulates fetal and mammary growth without causing lactation

Changes within what life phase have lasting effects on mammary growth?

Puberty

What is Growth Hormone's (GH) main function?

Repartitioning agent, meaning it redirects nutrients from other tissue to the mammary gland

What is the difference between livestock and rodents when transitioning from lactation to the dry period?

Rodent's mammary cells will die off through apoptosis, then re-form upon next pregnacy. Liverstock's mammary cells will not die off, but become smaller and go into an arrested state. Upon pregnancy, those cells will expand again, but if they do not become pregnant again those mammary cells will die off also.

How will the more primitive platypus secrete milk for its young?

Secretes milk onto its skin for its young to lap up

Upon parturition, what tissue/cells increase in the mammary gland?

Secretory tissue/milk-producing cells

What is one way to measure if tight junctions have formed between epithelial cells of the mammary gland?

Serum levels of α-lactalbumin (Alac); If there are no tight junctions, then Alac will continue to increase after calving. If there ARE tight junctions, Alac will decrease dramatically after calving.

Oxytocin has a (Long/Short) half-life.

Short; Therefore it is important to milk quickly after any stimulation

What is Serotonin's role in involution?

Shuts down mammary machinery when not used leading to involution; Also moves blood calcium into milk

Sensory receptors on the cow's ______ send signals to the brain to release ______ which constricts myoepithelial cells.

Skin; Oxytocin

Ergot Alkaloids block Prolactin release. Why does it completely stop lactation in women by 100%, but only blocks lactation in cattle by 50%?

Somatotropin (GH) stimulates mammary glands in cattle

Teat Cistern

Space immediately before Streak Canal; Holds very little milk

Gland Cistern

Space immediately following milk ducts of mammary gland; Holds 1 cup of milk

Mammary growth after parturition is ______ dependent.

Species

Calves grow faster in what season(s)?

Spring, Summer (longer days)

The inhibition of Prolactin can ______ a women's lactation. (___%)

Stop; 100%

Where are most mastitis-causing bacteria introduced to the animal?

Streak Canal

The number of mammary buds = number of ______ ______

Streak canals

Furstenberg's Rosette

Structure immediately before the streak canal that secretes keratin that will form a waxy keratin plug between milkings to prevent bacterial contamination

There are pain sensors on the ______ of mammary tissue.

Surface

Myoepithelial Cells

Surround Alveoli; Finger-like smooth muscle that contract upon stimulation by Oxytocin to push milk into Milk Ducts

The Mammary Gland is a modified ______ gland.

Sweat

Milk Secretion

Synthesis of milk plus its movement to alveolar lumen

The absence of what hormone leads to mammary gland development?

Testosterone

Both males and females develop mammary glands to a certain point. Why do males mammary gland discontinue development?

Testosterone increases to a point that limits mammary gland development

What are mammals defined by?

The presence of mammary glands

If you don't milk a pregnant cow, what will happen to her mammary glands?

They will stop producing milk, but will not involute

What are the 3 regions of mammary gland location?

Thoracic, Abdominal, Inguinal

How does Growth Hormone (GH) act since it doesn't have it's own receptors on the mammary gland?

Through IGF-I

What is the importance of the development of Tight Junctions prior to milk secretion?

Tight junctions create a seal between epithelial cells on the lumen-end of the cell. This makes it so milk will only be directed towards the lumen and cannot flow back between the cells towards the blood flow. These also make more Na+ enter the bloodstream, while more K+ enters the milk.

What causes Oxytocin release from the brain to cause Active milk let-down?

Touch, sight, smell, vaginal stimulation

Artificial lighting can be added during "short days" to increase Prolactin release and in turn increase milk production. (TRUE/FALSE)

True

Mammary gland development and lactation will influence all other parts of the body for their benefit. (TRUE/FALSE)

True

Mammary glands do not mix and will not use the same streak canal. (TRUE/FALSE)

True

Many mammalian species' mammary gland structure/function have not been characterized. (TRUE/FALSE)

True

The ducts present in 1 teat are completely separate. (TRUE/FALSE)

True

The mammary glands have priority over all other organs. (TRUE/FALSE)

True; As mammary gland needs increase, other organs needs are put aside

More milk will be produced with more GH. (TRUE/FALSE)

True; Depending on proper nutrition

By emptying udder of milk frequently, milk production goes ______.

Up

Prolactin ______- regulates its own receptor.

Up

Milk Duct

Where milk is secreted into after being produced by the Alveoli

If you put antibiotics into 1 quarter on a cow, it (Will/Will not) spread to the 3 remaining quarters.

Will; Via the blood stream

Growth type of Pre-puberty: ______ Growth type of Puberty: ______ Growth type of Post-puberty: ______

(Pre-puberty) Isometric (Puberty) Allometric (Post-puberty) Isometric

When does the 2nd stage of Lactogenesis occur?

1 week before parturition; Periparturient period (days)

What 2 Ergot Alkaloids inhibit Prolactin release?

1) Bromocryptine 2) Ergocryptine

What 8 changes are required for initiation of milk secretion (differentiation to synthesis/secretory cells)?

1) Cells need to differentiate to be able to synthesize/secrete fats, proteins, carbohydrates 2) Increased RER (rough endoplasmic reticulum) development 3) Golgi apparatus development 4) Increase in cellular mitochondria 5) Development of cellular directionality 6) Increased mammary blood flow 7) Development of microvilli (apical border) 8) Development of tight junctions

What are the 2 repartitioning effects Growth Hormone (Somatotrophin) has on the body?

1) Divert lipids to mammary gland 2) Divert glucose from tissue to mammary gland

For full mammary synthesis and secretion what hormones are needed? (5)

1) Estrogen 2) Progesterone 3) Prolactin 4) Growth Hormone 5) Glucocorticoids

What are the 2 stages of Lactogenesis?

1) Growth without lactation; Appearance of enzymes/milk components to prepare for milk synthesis 2) Hormonal changes cause final cell differentiation to secretory and synthetic capacity

What are the 2 main factors of mammary gland diversity?

1) Location 2) Number of ducts per teat

What are the 3 functions of Placental Lactogen?

1) Mammogenesis (mammary growth) 2) Fetal growth 3) Maternal intermediary metabolism: Affects maternal metabolic hormones (insulin/glucagon) to aid fetus

What 2 factors affect mammary growth around puberty?

1) Nutrition 2) Photoperiod

What are the 2 means by which milk is removed from the mammary glands?

1) Passive: Removal of milk from cisterns and large ducts; Not Oxytocin needed 2) Active: Activated by sensory; Oxytocin causes milk expulsion from alveolar lumen

The amount of Colostrum at birth influences what 2 things?

1) Pre-pubertal growth rate 2) Milk yield: More colostrum = more milk yield later on

What are the 3 main hormones of Lactation?

1) Prolactin 2) Growth Hormone 3) Oxytocin (Although many others are utilized)

What are the 2 functions of Growth Hormone (GH)?

1) Repartitioning Agent 2) Increase mammary blood flow

What are 3 factors that are involved in Prolactin release?

1) Stimulation of mammary gland (suckling, milking) 2) Temperature/seasonality (cold depresses) 3) Daylength (melatonin)

What are the 4 factors leading to milk withholding due to fright?

1) Vasoconstriction of mammary gland vessels reduces blood flow (less milk production) 2) Blockage of OT-R on myoepithelial cells; OT can't bind 3) Block release of OT from posterior pituitary 4) Constrict smooth muscle of teat sphincter

Milk has been a food source for ______ years.

10,000+

For every ___ Lb of preweaning difference in ADG, ______ Lb more milk will be produced during 1st lactation.

1; 1551

How many stages are there of Lactogenesis?

2

How many teats do marsupials (pouched mammals) typically have within their pouch?

2-4

What is the minimum amount of time for a dry period?

30 Days (45 days recommended)

How long will the smooth muscle of the teat sphincter stay contracted after a fright episode?

30 Minutes

Approximately how many mammalian species are there?

4000+

At what time in embryo development will the mammary bud form?

43 days

How many gallons of blood (approx.) are needed to make 1 gallon of milk?

500 gallons

Mammary growth and lactation require the coordination of at least ___ different hormones.

5; Estrogen, Progesterone, Prolactin, Growth Hormone, Glucocorticoids

As mammary gland growth increases, ______ ______ decreases

Adipose Tissue

When does the 1st stage of Lactogenesis occur?

All of gestation till 1 week before parturition (lasts weeks, months)

How does cell death occur in mammary gland cells?

Apoptosis

What factor from preweaning affects milk yield later on?

Average Daily Gain (ADG)

The inhibition of Prolactin in cattle only partially ______ lactation. (___%)

Blocks; 50%

What is another name for Growth Hormone cattle?

Bovine Somatotropin or BST