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Repro husbandry > Lactation > Flashcards

Lactation Flashcards

1
Q

During foetal development and pregnancy, what happens to the dam?

A

Mammogenesis

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2
Q

Before, during and after parturition, what takes place?

A

Lactogenesis

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3
Q

After parturition an during neonatal development, what takes place?

A

Galactopoiesis

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4
Q

What is the predominant dairy herd (UK)? What is the UK average yield?

A

Holstein

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5
Q

What is the average milk composition (fat, protein and lactose)

A

4% fat

  1. 2% protein
  2. 5% lactose
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6
Q

How has milk yield increased over the decades

A

Improved genetics (AI)
Improved nutrition
Improved technology

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7
Q

What problems are associated with lactation? (most problems are early lactation)

A 
Decreased fertility
Metabolic stress
Compromised immune function 
Mastitis 
Increased lameness
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8
Q

What is the majority of milk proteins?

A

Caseins

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9
Q

Apart from caseins, whey proteins are also in milk. What do they include?

A

B lactoglobulin
A lactalbumin
Immunoglobulins

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10
Q

Why might variation in milk composition occur?

A 
Between breeds
Between species
Across lactation and milking 
Nutrition 
With seasons
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11
Q

How is colostrum formed?

A

Pre-partum milk secretions that is not removed –> colostrum

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12
Q

Does colostrum provide passive or active immunity? Where are the immunoglobulins produced?

A

Passive

By plasma cells in the mammary gland

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13
Q

Describe the composition of colostrum in terms of fat, proteins, vitamins and lactose

A

High fat
High protein
High vit A
Low lactose

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14
Q

How long is colostrum secreted for? How long is milk withheld from human consumption?

A

Several days

4 days

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15
Q

Mammary glands form from which germ layers?

A

Ectoderm
Develop into mammary band
Mammary buds grow into underlying mesenchyme

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16
Q

What type of glands are mammary glands (simple, compound, alveolar, tubular, alveolar)?

A

Compound alveolar

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17
Q

What is the name of extra mammary buds formed during development? (Often removed in dairy heifers)

A

Supranumery teats

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18
Q

What separates the teat cistern from the glandular cistern?

A

Annular fold

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19
Q

What is present around the teat (streak canal)?

A

Sphincter muscle

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20
Q

What attaches the udder to the body? What does this consist of?

A 
Suspensory system (4 ligaments):
Median, lateral, pre- pubic and sub-pubic ligaments
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21
Q

The gross anatomy of the udder is separated into…

A

Rear and fore quarters (attached to body via rear/fore quarter attachment)
Mammary groove running between L and R teats

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22
Q

What is the name of the secretory tissue in mammary glands?

A

Parenchyma

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23
Q

What is the name of the ducts and storage sinus within a fat pad of the udder? What happens here?

A

Cistern

udder cistern and teat cistern

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24
Q

Ducts move milk from where to where?

A

Alveoli to teat

No internal crossover

25
Q

Where is miked stored between milking?

A

Some in cisterns

Most in alveoli

26
Q

How does the teat canal respond to infection?

A

Cytokine production

27
Q

The alveoli consists of what cell arrangement?

A

Polarised, epithelial secretory cells

28
Q

What surrounds the alveoli?

A 
Myoepithelial cells (smooth muscle)
Blood vessels
29
Q

How is milk ejected from alveoli into ducts?

A

Contraction of myoepithelial cells

30
Q

What are the secretory cells? From which surface is milk synthesised?

A

Cells on basement membrane surrounded by collagenous extracellular matrix
Apical surface

31
Q

What is the prime determinant of milk yield?

A

Number of secretory cells

32
Q

What happens to the cells in the udder during pregnancy and early lactation?

A

Proliferation of secretory cells displace fat pads

Mainly differentiation in early lactation

33
Q

Describe growth of the mammary tissue during puberty and during oestrus cycles

A

Puberty = isometric growth (grows in proportion to rest of body)
Oestrus cycle = allometric growth (grows at different rate to rest of organs) and regression

34
Q

What happens to the cells of the udder during declining lactation?

A

Apoptosis

And involution

35
Q

Which hormones cause duct growth?

A

Oestrogen
Growth hormone
Adrenal steroids

36
Q

Which hormones cause lobulo-alveolar growth?

A 
Oestrogen 
Growth hormone 
Adrenal steroids
Prolactin 
Progesterone
37
Q

Which hormones cause milk secretion?

A

Prolactin

Adrenal steroids

38
Q

What are the phases that take place to cause milk secretion?

A

Atrophic ducts
Duct growth
Lobulo-alveolar growth
Milk secretion

39
Q

Which hormones are important in the control go bovine mammary cell proliferation?

A

Placental lactose
Growth hormone
(NOT PROLACTIN)

40
Q

What are the 2 stages of lactogenesis?

A

Acquisition of secretory capability pre-partum

Onset of copious secretion at parturition

41
Q

What hormone is the main requirement for lactogenesis?

A

Progesterone withdrawal

42
Q

How is milk ejected from the gland?

A

Teat stimulation causes neuro-endocrine reflex
Oxytocin released from posterior pituitary
Myoepithelial cells in mammary gland contract
Positive pressure in the udder causes milk to be pushed out

43
Q

Describe a basic milking routine

A

Clean (predip/wipe) udders
Identify animal
Inspect for clots
Leave 30-45 seconds for oxytocin release and action
Cluster on then removed
Teat dip applied post milking
Loafing time to allow teat sphincter to close

44
Q

What is galactopoeisis?

A

Maintenance of established lactation

45
Q

What does continued milking do to allow galactopoiesis?

A

Prevents milk stasis

Stimulates the release of galactopoiesis hormones

46
Q

How does milk stasis inhibit milk secretion? (2 ways)

A 
Feedback inhibition (within hours)
Physical disruption (within days)
47
Q

In most species, what hormone drives lactation? Which species is the exception and what hormone drives their lactation?

A

Most species = prolactin

Cows = growth hormone

48
Q

A 3 quarted cow reduces yield by what percentage?

A

10% (not 25%)

49
Q

How can milking yield be increased?

A

Recombinant bovine somatotropin (rBST)
Genetic improvement
Nutrition
Frequent milking

50
Q

Is BST legal in the EU? Why?

A

No
Burnt out after one lactation and replaced
Causes lameness and painful injection abscesses

51
Q

How does bovine somatotropin cause an increased milk yield?

A

Redirects nutrients towards the other

52
Q

Give one way that milk production can be inhibited to match supply to demand

A

Feedback inhibitor of lactation (FIL - autocrine peptide)

Negative feedback

53
Q

Large cistern cows produce more milk per gram of secretory tissue. Do large cistern cows tolerate frequent or infrequent milking better?

A

Tolerate infrequent milking

Respond less well to frequent milking

54
Q

After peak lactation, what causes milk yield to decrease?

A

Decreased number of secretory cells by apoptosis

Due to FIL and lack of gelactopoietic hormones

55
Q

What stimulates apoptosis of secretory cells?

A

Weaning
Milk stasis
Local increase in IGFBP5

56
Q

What inhibits apoptosis in secretory cells?

A

Prolactin
Growth hormone
IGF1

57
Q

What are the types of milking parlour?

A 
Abreast
Tandem 
Herring bone 
Rapid exit
Rotary 
Robot
58
Q

How milking clusters cause milking?

A

Vacuum creates negative pressure outside the teat
Pushes milk out
Vacuum on:off 2:2

Repro husbandry (11 decks)

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