Download ANATOMY AND PHYSIOLOGY OF UDDER

ANATOMY AND PHYSIOLOGY
OF UDDER
OBJECTIVE:
1. Understanding the external and
internal structure of udder
2. Where and how milk to be secreted
CORE SUBJECTS:
• 1. Anatomy of the udder
• 2. Internal structure of the udder
• 3. Physiology of the udder
Introduction
• Milking is the process of persuading the cow
to let down its milk and allow dairy farmer to
remove it for his or her own consumption or
for sale.
• It is therefore not entirely a natural process.
• The dairy farmer must manipulate the natural
process so that he receives the maximum
benefit.
• It is therefore essential that one understands
the natural process in order to manipulate it.
Mammary glands are the major features that
distinguish mammals from other kinds of
animals.
Cow
Goat
Sheep
Mammary glands are the organs that, in mammals,
produce milk for the sustenance of the young.
The teats and glands can occur anywhere along the
two milk lines, two roughly-parallel lines along the
ventral of the body.
Pig
Cat
Mouse
In general most mammals develop mammary glands
in pairs along these lines, with a number
approximating the number of young typically birthed
at a time.
The number and positioning of complex and simple
mammary glands varies widely in different mammals.
Elephant
Human
The number and position of glands normally
found in a range of mammals:
Species
Anterior
(thoracic)
Intermediate
(abdominal)
Posterior
(inguinal)
Total
Goat, sheep,
horse
0
0
2
2
Cattle
0
0
4
4
Cat
2
2
0
4
Dog
2
4
2-4
8-10
Mouse
6
0
4
10
Pig
6
6
4
16
Elephants,
primates
2
0
0
2
Suckling baby elephants
Suckling baby elephants
Suckling baby elephant
Several examples of species that reflect the range of
anatomical location and number of glands or teats.
Species
Location (region)
Num of
glands
Num of
teats
Cow
Ewe, doe
inguinal (groin)
inguinal (groin)
4
2
4
2
Mare
Sow
Cat
Dog
inguinal (groin)
abdomen
abdomen
abdomen
4
10-14
10-14
10-14
2
10-14
10-14
10-14
Human
Elephant
thoracic (pectoral)
thoracic (pectoral)
2
2
2
2
Anatomy of the udder
• Located in the groin
(inguinal) area
• Consists of four
separate glands
(quarter), each gland
has one teat with one
opening
(cow)
• Rear quarters account
for 55-60% of total
udder weight and
produce 55-60% of milk
• Total weight: 50 lb of
empty udder + 60 lb of
milk in the gland, or
110 lb suspended from
the body prior to
milking ----->
• attachment of udder
to the body is critical
Suspensory System
• Support system:
median and lateral
suspensory ligaments
• Right and left halves
are separated by
intermammary groove
Location of udder, quarters, teats,
proportion and attachment
What are the specific anatomical structures of the udder
that are involved in holding the udder onto the body wall?
• The cow in image A below
has an udder that is held
firmly to the body wall.
• In contrast, the cow in
image B below has a deep
udder that hangs down
away from the body.
• What are the differences in
those structures between
the cow in A vs B?
External and internal structure
•
•
•
•
•
•
•
•
•
Teat, streak canal and sphincter, teat cistern
Gland (udder) cistern
Fatty tissue
Connective tissue
Milk ducts
Lobules, lobes
Alveoli, secretory (epithelial) cells
Lumen
Myoepithelial cells, oxytocin hormone,
capillary bed
The inside of the udder has two main type of tissue:
• Connective (fibrous)
tissue or collagen
• Fatty tissue
(adipose cells)
• Secretory
(glandular) tissue:
– Milk ducts
– Lobules, lobes
– Alveoli, secretory
(epithelial) cells
– Lumen
– Myoepithelial cells,
oxytocin hormone,
capillary bed
Internal structure of mammary gland
Internal structure of mammary gland
Diagram of alveolus showing lumen, epithelial cells.
myoepithelial, and capillaries.
Form lobe and lobules
a. Lobule: contain 150 to 225
alveoli
b. Tissues involved in milk
synthesis
Epithelial cells: synthesis and
secretion of milk into lumen of
alveoli
c. Tissues involved in milk
transport
Milk flows from lumen alveoli,
ducts, major ducts, gland
cistern, teat cistern, teat meatus
d. Myoepithelial cells: Covers
surface of alveoli and small
ducts down within a lobule:
contraction for milk ejection
Internal structure of mammary gland of cow
• Diagram of the duct
system in one
quarter of the
mammary gland of
the cow with a
single lobe
illustrated.
• Four quarters are
fused into a single
gland complex.
• Diagram of the gland complex
found in the mare.
• Diagram of a cross section of
the supporting structures of
the mammary glands of the
cow as viewed from the rear.
• Lateral suspensory ligaments:
not elastic, and sends lamellae
into udder, continuous with
interstitial framework
Median suspensory ligament:
elastic, and stretch as udder
fills with milk
Blood vascular system
• The blood supply to the mammary gland is
extremely important for mammary function! All of
the milk precursors come from blood.
• On avg. 400 - 500 units of blood passes
through the udder for each unit of milk
synthesized by a high producing dairy cow;
that is ~280 ml per sec.
• High producing dairy goats have a lower (460:1)
ratio of blood flow through the gland:milk
produced, compared with low producers
(1000:1).
• This means that the amount of blood flow
through the mammary gland may by similar for
the high and low producing goats, but the
efficiency of extraction of the components from
the blood while it passes through the udder is
very important. This principle is probably similar
for cows.
• Total udder blood volume for lactating cows about
8% of total body blood volume, while for a nonlactating cow it is about 7.4%.
• There is a 2-6 fold increase in blood flow in the
mammary gland starting 2-3 days prepartum.
• The decrease in production with advancing
lactation is not due to decreased blood flow, but it
is due to the loss of secretory (epithelial) cells
through a process programmed cell death
(apoptosis).