Lecture 13 - Lactation pt 1 Flashcards
(42 cards)
1
Q
Why can’t we feed swine milk from bovines?
A
- milk composition is species specific
- would be short on how much fat (energy) they are getting
2
Q
What 2 monosaccharides join to make lactose?
A
galactose + glucose
3
Q
What is ash?
A
- close to 1% of milk
- iron, magnesium, iron, phosphorus
4
Q
How is the mammary gland structure species specific?
A
- location
- number of glands
- largely associated to how many offspring they have - number of cisterns
- number of teat canals
5
Q
What is the mammary gland structure of the udder?
A
- 4 separate glands
- one teat in each quarter
6
Q
What are supernumerary teats?
A
- extra nonfunctional teats
- get removed when calf is young
7
Q
What are key aspects of good conformation of teats?
A
- moderate size
- central in each quarter
- tight sphincter
8
Q
What are the 3 major supporting structures of the mammary gland?
A
- skin
- median suspensory ligament
- lateral suspensory ligament
9
Q
Median suspensory ligament
A
- supporting structure of the mammary gland
- separates right and left halves of udder
- connects udder to abdominal wall
- elastic tissue which responds to wt of milk in udder
10
Q
Lateral suspensory ligament
A
- inflexible
- surrounds the outer wall of the udder
- attached to prepubic and subpubic tendons
11
Q
Intermammary groove
A
- left x right halves
- where median and lateral suspensory ligaments meet
- indicates the cow has good attachment; well attached udder fits snugly against the abdominal wall in front and on the sides
12
Q
Characteristics of a good, non-lactating udder?
A
- fully collapsed
- firm attachment
- uniform teats
13
Q
Characteristics of a good, lactating udder?
A
- strongly attached
- teat size and shape
- udder size
14
Q
Abnormalities of a bad udder
A
- attachment failure
- udder size and shape
- teat size, shape, and placement
15
Q
What is the alveolus?
A
- functional, milk production unit
- bulb shaped
- hollow center
- lined with epithelial cells
16
Q
What is the fxn of epithelial cells of the alveoli?
A
- milk synthesis and secretion
17
Q
What is the fxn of the lumen of alveoli?
A
- collect milk components and water
18
Q
What is the fxn of myoepithelial cells of alveoli?
A
- milk ejection
- contract in response to oxytocin
19
Q
What is the fxn of the basement membrane of alveoli?
A
- separates epithelial and myoepithelial cells
20
Q
What is the fxn of the terminal duct of alveoli?
A
- milk transport out of alveoli
21
Q
What is the fxn of the capillary system of alveoli?
A
- support milk precursors, deliver hormones, support blood supply
22
Q
Alveoli duct system
A
- storage and transport
- 2 layers of epithelium
- myoepithelial cells arranged in a longitudinal pattern; contraction = milk flow
23
Q
Furstenburg’s rosette
A
contributes to immune cell population
24
Q
What does the streak canal do?
A
- keeps milk in (tight) and bacteria out
25
What are the 4 development processes of mammary tissue?
1. mammogenesis
- tissue growth and development
2. lactogenesis
- differentiation of alveolar cells into milk producing and secreting cells
3. galactogenesis
- maintencance/enhancement of lactation
4. involution
- when cow is no longer lactating, the tissue that has been built needs to all go away
26
What is happening to the mammary gland from birth to puberty?
1. isometic growth = mammary growing at same rate as the rest of the body
2. hormones impacting growth
27
What is happening to the mammary gland from puberty to conception?
1. allometric growth starts before first estrus = mammary growing faster than the body
- induced by estrogen
2. estrogen (ovary)
- branching/elongation of ductal system
- increased vascularity
3. prolactin and somatotropin
- contribute to overall growth
28
What is happening to the mammary gland from conception to parturition?
1. allometric growth
2. exponential parenchyma proliferation
3. early: branching/elongation of ductal system
4. late: alveolar development
5. hormones contributing to growth
6. insulin + IGF-1
7. thyroid hormones increase metabolic rate
29
Lactogenesis
Late gestation
- high P4; stops lactation from happening
- block prolactin receptor synthesis
Parturition
- P4 falls
- prolactin receptors synthesized
Prolactin stimulates synthesis of alpha-lactalbumin initiating secretion of milk
30
Milk ejection reflex aka how is milk secreted?
- oxytocin and prolactin released from pituitary following stimulation of skin on teats (or sight/smell/sounds of calf)
- Oxytocin has 3 stimulatory effects on the udder
1. increases pressure in alveolar lumen; myoepithelial cells contract
2. reduces resistance in small excretory ducts
3. reduces resistance in teat canal
31
Factors affecting emptying of the udder
Activation of sympathetic nervous system inhibits milk let-down by:
- reducing secretion of oxytocin
- inhibiting the response of myoepithelial cells to oxytocin
- eliciting contraction of the smooth m cells in the sphincter at the top of the teat
- reducing blood flow to udder
32
What can larger residual milk volume in the udder lead to? aka what is a concern by the sympathetic nervous system being activated and inhibiting milk let-down?
reduced production and increased risk of infection
33
What are 3 controls of milk secretion?
1. physical control
- removal rate
- gland storage capacity
- intramammary pressure
2. chemical control
- feedback inhibitor of lactation- slows milk secretion; produced in response to increased pressure
3. after milking
- prolactin release is stimulated
- decrease in intramammary hydrostatic pressure
- FIL is removed from alveoli
34
Involution/Dry-period
- when we stop milking we are going to have involution where the tissue degrades back to a prelactation form
- feedback inhibitor of lactation (FIL) produced in mammary in response to pressure in alveoli
- alveoli shrink down and lose secretory capacity but are maintained for when she is pregnant; if waiting long enough they degrade
35
How much blood does one gallon of milk require?
- one gallon of milk requires 400 gallons of blood being passed through the udder
- ratio may increase in low producing cows
36
Path of blood to the mammary arteries
- heart
- caudal aorta
- iliac arteries
- external pudic arteries
- mammary arteries
37
How is milk returned to the heart from the mammary veins?
1. mammary veins, external pudic vein, iliac veins, caudal vena cava, heart
2. mammary veins, subcutaneous abdominal vein (milk vein), cranial vena cava, heart
38
6 characteristics of lymph (which is also going to the mammary)
- less protein than blood plasma
- high concentration of lymphocytes (aka immune cells)
- few RBC's
- carries glucose, salts, fat
- dissipates heat
- carrier of fibrinogen (clotting protein)
39
How can the movement of lymph be described?
Passive
- muscle movement
- breathing
- heart beat
- tissue massage
40
What are the 4 main fxns of the lymphatic system?
1. helps regulate proper fluid balance within the udder
2. immune fxn (lymphocytes
3. fluid drained from tissue only travels away from udder
4. lymph travels from udder to the thoracic duct and empties into blood system
41
Edema
- accumulation of interstitial fluid
- lymphatic: low pressure, passive system
- circulatory system: high pressure, active system
= pooling of interstitial fluid if evacuation of lymph is impaired
42
What 5 things can prevent edema?
1. preparturient milking
2. frequent milking to reduce mammary pressure
3. diuretics, corticoids to reduce swelling
4. mammary massage, icing
- work fluid towards supramammary lymph nodes
5. reduce salt intake
