Cow Udder

Question 1

Modern Cow milk production

Answer 1

-cows been selected for and developed for maximum milk production
-From 6kg/cow/day to 26.6kg/cow/day (4.4 fold increase)

Question 2

Modified sweat glands

Answer 2

-part of the integumentary system

Question 3

Development of modified sweat glands

Answer 3

1.start as buds growing into ectodermal ridges
-form in bilateral pairs

2. supernumerary buds regress (reason why embryos have much more than adults)

Question 4

Modified sweat gland location for species

Answer 4

-Carnivores and pigs: thoracic to inguinal
-Primates: thoracic
-Ruminants and horses: inguinal

Question 5

Time length for development of buds and ducts

Answer 5

**minimal development early
Buds: ~75 day gestation
Ducts: start forming ~100days (appear as hair follicle)

Question 6

Modified sweat glands at birth

Answer 6

-teats well developed
-Has both a rudimentary duct and canalized secondary ducts below
-secretory system not developed yet

Question 7

Modified sweat gland development from birth to puberty

Answer 7

-increased weight and capacity (60% increase from birth to weaning)
>increased connective tissues and fat deposition
>continued ductal growth and development

Question 8

What can influence udder development?

Answer 8

-significantly influenced by nutrition
**critical period for future production (more growth early=more production later)

Question 9

Effect of nutrition on udder development

Answer 9

-When not fed enough or the proper feed, can lead to restricted ducts and poor ilk production later in life

Question 10

Appearance of udder immediately pre-breeding (1 yr)

Answer 10

-will have large fat pad
-teat, teat cistern, secondary ducts

Question 11

Teat cistern

Answer 11

-where milk accumulates

Question 12

Changes in udder during gestation

Answer 12

-marked increase in growth
-Early: ductal growth and development
-Mid: cistern growth at 5-6 months, gland proliferation at 5-7 months, secretory tissue replaces adipose tissue
-Late (6-9 months): secretory tissue, vascular and lymphatic proliferation. Secretory activity begins.
**Late stage repeats each gestation

Question 13

What changes occur when cow is dried off?

Answer 13

-secretory tissue apoptosis and is replaced by more secretory tissue

Question 14

Structure of flow in udder of mature mammal

Answer 14

1.Lobule
2. Intra- and inter-lobular ducts
3.Lactiferous ducts
4. Lactiferous sinus
5. Gland sinus (milk let down into teat cistern due to oxytocin release)
6. Teat cistern
7.Papillary duct (teat canal)
8. Teat sphincter
9. Teat orifice
10. Parenchyma
11. Skin: thin and freely movable

Question 15

Lactiferous duct separation

Answer 15

-fore and hind quarters are separate
**one duct system per quarter therefore no communication between any of the ducts

Question 16

Bovine teat structure

Answer 16

-skin is hairless and glandless
-middle fibro-muscular with cavernous sinuses
-inner mucosa: 2 layers of cuboidal cells

Question 17

Immune protection of teat

Answer 17

-blood-milk barrier- prevent pathogens entering
-teat canal important in preventing bacteria entering teat. Has rosette (lymphatic tissue with immune cells)

Question 18

Cell structure of teat

Answer 18

-Outer portion is stratified squamous
-inner portion is cuboidal epithelium as you move internally

Question 19

Ovine teat

Answer 19

-smaller version of bovine
-Glandular part (alveoli)
-Lactiferous sinus
-teat part
-Teat canal (papillary duct)

Question 20

Horse teat

Answer 20

-2 systems out of one teat (cranial and caudal)
>infection on one system will likely infect the other system as well
-each teat is separated from each other

Question 21

Canine Teats

Answer 21

-many teats in lines
-more obvious that they arise from the ectodermal ridge

Question 22

Gland locations for different species

Answer 22

-Pig: located in thoracic, abdominal, and inguinal regions
-Dog: thoracic, abdominal, and inguinal regions
-Cat: thoracic, abdominal, inguinal regions
-Primate: thoracic
-Cow: inguinal
-Sheep: inguinal
-Horse: inguinal

Question 23

of duct systems per gland for different species

Answer 23

-Dog, Cats, Primates: multiple duct systems per gland/teat
-Pig, Horse: two duct systems per gland/teat
-Cow, Sheep: one duct system per gland/teat

Question 24

Supernumerary Teat

Answer 24

-an additional teat
-occurs when during development, one of the mammary buds fails to regress

Question 25

Blood flow in udder

Answer 25

-500L of blood flow is needed per L of milk
-20L milk per milking = 10,000L blood= 250x the blood volume of a cow

Question 26

Main lymph nodes draining udder

Answer 26

-Prefemoral/precrural lymph node
-supramammary lymph nodes

Question 27

What can cause enlargement of the supramammary lymph nodes?

Answer 27

-mastitis

Question 28

Important vasculature of the udder

Answer 28

-External pudendal
-Internal Pudendal
-Perineal
-Superficial abdominal “milk” vein (connected to cranial epigastric vein and joins with musculophrenic vein and becomes internal thoracic)
-right and left cranial mammary veins
-right and left caudal mammary veins
-superficial udder veins

Question 29

Milk vein development

Answer 29

-vascular ring at the base of the udder
>anastomoses between the cranial and caudal superficial epigastrics
>incompetent valves

Question 30

Why should you never use milk vein for vascular access?

Answer 30

-collapse
-introduce contamination
-milk vein is thin walled so laceration can occur easily. Animal will bleed out very quickly (2-3mins)

Question 31

Main innervation of the udder

Answer 31

-genito-femoral nerve (from L3 and L4)
>innervates the bulk of the gland and teats (somatic and autonomic)
-Pudendal nerve (from S2 and S3)
>innervates caudal surface (superficial sensation )

Question 32

Mass of udder

Answer 32

~50kg milk and more than 50kg of blood
Also includes parenchyma, fat, etc.
**Total weight is ~100-150kg (Cow weight = ~750kg)

Question 33

Suspensory apparatus

Answer 33

-includes a right and left medial laminae (fanning out between halves) and a lateral laminae (outer edge stretching up into body wall)

Question 34

Suspensory ligament collapse

Answer 34

-occurs when medial or lateral laminae breaks down
-results in udder dragging on/near ground
-not surgically repairable as it is not usually due to just one tear. Usually due to stretching out of many parts

Question 35

How do you orient the caudal vs. cranial teats of udder?

Answer 35

Caudal are closer together than the cranial teats

Question 35

Official name for a teat

Answer 35

Mammary papillae

Question 36

Teat components

Answer 36

-Teat canal/papillary duct
- papillary duct mucosa called rosette
-lactiferous sinus (both glandular and teat parts)
-lactiferous ducts

Question 37

Where does the milk vein pass through?

Answer 37

passes through a milk well (at the second tendinous intersection of rectus abdominis ventral to the 7th through 9th intercostal spaces)