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Y2 AHW > Lactation > Flashcards

Lactation Flashcards

1
Q

When does mammary gland development begin?

A

Whilst the foetus is in utero - teats can be seen on an ultrasound

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2
Q

What is the predominant dairy breed?

A

Holstein

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3
Q

How how the dairy herd yield been increased progressively despite the number of farms decreasing?

A
  • Improved genetics (AI)
  • Improved nutrition
  • Improved technology
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4
Q

Why had yield advanced the most amongst dairy breeds?

A

It has the highest heritability

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5
Q

What are some of the main problems associated with lactation?

A
  • Decreased fertility
  • Compromised immune function
  • Increased lameness
  • Mastitis
  • Metabolic stress
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6
Q

What are the 3 major components of all milks?

A

Protein
Fat
Lactose

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7
Q

What are the major proteins of milk and where are they found?

A

Caseins - found in the curd

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8
Q

For how many days is milk withheld for human consumption following parturition?

A

4

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9
Q

Colostrum provides what type of immunity?

A

Passive

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10
Q

What are the components of colostrum?

A
  • high in fats, protein, and vitamin A

- low in lactose

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11
Q

Describe the embryology of mammary glands

A
  • Two parallel lines of ventro-lateral ectoderm in the embryo
  • Develop into thickenings known as mammary band
  • Mammary buds grow into underlying mesenchyme
  • Mammary glands = epithelial
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12
Q

What occurs following the removal of a wrong supernumerary teat?

A

1/4 of the udder won’t be able to release milk

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13
Q

What anatomy makes up the mammary gland?

A
  • Teat/nipple and associated ducts

- Alveoli, secretory cells and supporting tissues

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14
Q

Which structure separates the gland cistern from the teat cistern?

A

Annular fold

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15
Q

Which ligaments form the suspensory system attaching the udder to the body?

A
  • Median suspensory ligament

- Pre-pubic and sub-pubic ligaments

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16
Q

Describe the structure of the gland

A
  • secretory tissue (parenchyma)
  • ducts
  • storage sinus (cistern) lying in a fat pad
  • terminating externally in a teat or nipple
17
Q

What is the function of the cistern between the teat and udder?

A

Large cavity where milk can collect between milking

18
Q

Despite the presence of large cisterns, where is most of the milk actually stored?

A

Alveoli

19
Q

The alveolus is a basket like arrangement of what type of cells?

A

Polarized epithelial secretory cells

20
Q

What surrounds the polarized epithelial secretory cells in the alveolus?

A

Myoepithelial (smooth muscle) cells and blood vessels

21
Q

The number of secretory cells is a prime determinant of what?

A

Milk yield

22
Q

Until puberty mammary tissue grows at what rate?

A

Same as the rest of the body - isometric growth

23
Q

Following puberty/oestrus cycle, at what rate does mammary tissue grow at?

A

Faster than the rest of the body - Allometric

24
Q

How do mammary cells change from gestation to the end of lactation?

A
  • Secretory cells proliferate during gestation
  • Some proliferation in early lactation, but mainly differentiation
  • Gradual involution (apoptosis) during declining lactation
  • Rapid involution after drying off or weaning
25
Q

Which hormones cause growth of ducts?

A

Oestrogen + growth hormone + adrenal steroid

26
Q

Which hormones cause milk secretion?

A

Prolactin + adrenal steroids

27
Q

Describe stage 1 and 2 of lactogenesis

A
  1. Acquisition of secretory capability pre-partum

2. Onset of copious secretion at around parturition

28
Q

What is the main hormonal requirement for the onset of lactogenesis?

A

Progesterone withdrawal

29
Q

How does the foetus syncronise stage 2 of lactogenesis with parturition/milk production?

A
  • The foetus signals from its own hypothalamus and pituitary to secrete cortisol from the adrenal gland
  • This passes across the placenta and increases oestrogen levels
  • This stimulates PGF2a release from the uterus
  • This goes to the ovaries causing luteolysis of the CL, and a decline of progesterone
  • This stimulates labour and production of milk
30
Q

Teat stimulation evokes which reflex?

A

Neuroendocrine reflex - develops positive pressure in the udder

31
Q

Describe the milk-ejection reflex

A
  • Teat stimulation causes afferent inputs to go to the hypothalamus
  • Causes oxytocin to be released from the posterior pituitary
  • Leading to contraction of myoepithelial cells in the mammary gland
32
Q

Describe a milking routine

A
  • Clean teat (pre-dip or wipe)
  • Inspect for clots - foremilk
  • Leave for 30 seconds to allow for oxytocin action
  • Cluster on
  • Milk flow reduced
  • Cluster off
  • Post milking teat dip applied
33
Q

What is galactopoiesis?

A

Maintenance of established lactation

34
Q

Continued milking does 2 things, what are they?

A
  • Stimulates the release of galactopoietic hormones

- Prevents milk stasis

35
Q

How is the drive for lactation different in cows to most species?

A
  • In cows it is GnRH driven

- In most other species it is prolactin driven

36
Q

What is BTS and why is it now banned in the EU?

A
  • Method that significantly increased milk yield of dairy cows
  • But had serious consequence on health and welfare
37
Q

What 3 things inhibit apoptosis?

A
  • Prolactin
  • GH
  • IGF1
38
Q

What 2 things stimulate apoptosis?

A
  • Weaning

- Milk stasis

39
Q

How long is the optimal dry period?

A

60 days

Y2 AHW (15 decks)

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