Mammary Glands and Lactation

Question 1

Where is all mammary tissue derived from?

Answer 1

Ectoderm

Question 2

When does the band vs line vs bud stage occur?

Answer 2

Band 30d
Lines 35d
Bud 65d

Question 3

What cell types differentiate into teat and gland cisterns?

Answer 3

Sprouts (galactophores)

Question 4

What determines the number of openings per teat?

Answer 4

Number of galactophores

Question 5

When does isometric growth occur?

Answer 5

Birth to 2-3m

Question 6

When does allometric growth occur?

Answer 6

1-3m to 1yr

Question 7

What 2 hormones are important in mammary tissue growth?

Answer 7

Estrogen: ductal development
Progesterone: stromal cell proliferation, ductal side branching and alveolar bud formation

Question 8

Hormones: Short-Cycling Mammals

Answer 8

Mice, rats, hamsters, gerbils
Little progesterone available so no alveoli or end buds until pregnancy

Question 9

Hormones: Long-Cycling Mammals

Answer 9

Production of FSH and LH
Ovaries = estradiol (duct development), progesterone
Progesterone, prolactin = lobules and alveolar development

Question 10

Define: Lactogenesis

Answer 10

Cell differentiation, milk secretion

Question 11

Progesterone Inhibitory Effects

Answer 11

Inhibits production of alpha-lactalbumin (glucose to lactose)
Blocks glucocorticoid effects

Question 12

Estrogen Stimulatory Effects

Answer 12

Decreases anterior pituitary lactotroph sensitivity to dopamine –> prolactin secretion

Question 13

Prolactin Stimulatory Effects

Answer 13

Increases receptors
Increases casein synthesis
Stimulates synthesis of alpha-lactalbumin

Question 14

Placental Lactogen Stimulatory Effects

Answer 14

Binds to prolactin receptors

Question 15

What hormones are associated with milk ejection?

Answer 15

Oxytocin stimulates letdown
Epinephrine inhibits letdown

Question 16

When is peak milk production?

Answer 16

90d

Question 17

What causes ketosis?

Answer 17

Late term fetus = high lactose synthesis = lack of CHOs = increased lipolysis = increased NEFAs = ketones

Question 18

What are the 2 stages of involution?

Answer 18

Active
Steady State

Question 19

Define: Active Involution

Answer 19

Milk secreted at unchanged rate for 2-4d
Complete cessation after 30d

Question 20

Define: Steady State

Answer 20

Secretory cells are reduced gradually
If dry too long, replaced by adipose tissue and subsequent production reduced

Question 21

What is the recommended goal of milk involution?

Answer 21

45d
(70-80+ = detrimental)

Question 22

What are the components of milk?

Answer 22

Water 88%
Lactose 4.9%
Fat 3.4%
Protein 3.3%
Minerals 0.7%

Question 23

Define: Milkfat Depression Syndrome

Answer 23

<3.3% fat or fat/protein inversion
High milk production = low fiber ration, forage too fine or coarse
Low milk production = severe energy defectis, acetate diverted to ketone production

Question 24

Define: High Milkfat

Answer 24

> 3.8%
Fair to poor milk production, severe body condition loss
Inadequate energy intake
Insufficient glucose/propionate for lactose synthesis

Question 25

What are the 3 most important factors for passive transfer?

Answer 25

Quantity (one gallon)
Quality (healthy dam)
Quickness (within 1st 5h)