This document discusses pregnancy, parturition (birth), and lactation in domestic animals. It describes the hormones involved in pregnancy like progesterone and relaxin. Gestation periods vary by species from 114 days in sows to 336 days in mares. Parturition involves three stages: dilation of the cervix, delivery of the fetus, and delivery of the placenta. Lactation is enabled by galactopoiesis and milk ejection in response to suckling. The mammary glands secrete milk containing nutrients for offspring. Colostrum provides early immunity before transitioning to mature milk. Lactation declines as alveoli decrease and connective tissue increases.

1. PREGNANCY AND
PARTURITION

2. PREGNANCY
Is the condition of a female animal while young are
developing within her uterus
Full term pregnancy – if the young are carried
throughout a normal gestation period
Premature birth – is a delivery of a viable fetus
before fetal development is complete
Abortion – termination of pregnancy with delivery of
a nonviable fetus

3. GESTATION PERIOD
 it is the interval from fertilization of the ovum to the birth of the
offspring
 Normal gestation period varies greatly from species to species
Animal Onset of
Puberty
Age of First
Service
Estrus
Cycle Estrus
Gestation
Mare 18 months 2-3 years 21 days 6 days 336 days
Cow 1-2 years 1-2 years 21 days 18 hours 282 days
Ewe 8 months 1-1.5years 17 days 1-2 days 150 days
Sow 7 months 8-10 months 21 days 2 days 114 days

4. HORMONES OF PREGNANCY
Progesterone
- a steroid hormone released by the corpus luteum
that stimulates the uterus to prepare for pregnancy.
- providing negative feedback to the hypothalamus to
inhibit any further estrous cycles
- inhibiting the smooth muscle of the uterus to permit
attachment and development of the fetus
- assisting with maintenance of the contractility of the
cervix to protect the uterine environment

5. HORMONES OF PREGNANCY
Equine Chorionic Gonadotrophin
- formerly known as pregnant mare serum
gonadotrophin or PMSG
- the hormone is commonly used in concert with
progestogen to induce ovulation in livestock prior to
artificial insemination.
- begins after a month of gestation and continues
until about 4 months of gestation

6. HORMONES OF PREGNANCY
Relaxin
- is a protein hormone secreted by corpus luteum in
some species (sow and cow) and the placenta in others
(bitch and mare)
- the primary function of relaxin is preparation for
parturition and ultimately lactation
- contributes to the opening of the cervix and the
relaxation of the muscles and ligaments associated with
the birth canal to facilitate the passage of the fetus

7. PREGNANCY DIAGNOSIS
 *Failure to have another estrous cycle at the expected
time*
Palpation of the reproductive tract via the rectum in the
mare and cow can be useful
Ultrasonography is used to diagnose pregnancy in a
variety of domestic specie, including cattle, horses,
sheep, goats, llamas and swine

8. PARTURITION – the act of giving birth to
young
Three Stages of Parturition
First Stage – uterine contractions that gradually force the
fetus and fetal membrane to the cervix ( 2-6 hours in cow
and ewe, 1-4 in the mare and 2-12 hours in the sow)
Second Stage – actual delivery of the fetus occurs
Third stage – delivery of the placenta, which normally
follows the fetus almost immediately

9. LATE GESTATION
Swelling of the vulva, and mucus discharge
Muscles on both sides of the tail head may relax and
appear lowered or depressed
Mammary glands enlarge and may secrete a milky
materials for a few days prior to parturition
Animals may become restless, seek seclusion, and
increase the frequency of attempts to urinate
The bitch and sow often try to build a nest

10. OXYTOCIN
Acts directly on uterine contraction and promote
delivery
Stimulate contractions of fatigued uterus during
prolonged labor

11. FETAL PRESENTATION AND DELIVERY
Cranial (anterior) presentation – normally presented
front feet first with the head extended and the nose
between the front feet
Caudal (posterior) presentation – hind feet first,
hocks up, occurs frequently enough in cattle to be
considered normal

13. COMMON PROBLEM DURING
PARTURITION

14. DYSTOCIA
Difficult birth
In some cases, birthing is not possible without
assistance
In general, from the onset of labor, cows should
calve within 8 hours, ewes should lamb within 2
hours, and mares should foal within 2-3 hours. Sows
should average one offspring per hour until farrowing

16. ANATOMY AND PHYSIOLOGY OF THE
MAMMARY GLANDS

17. MAMMARY GLAND
 also called mammae, are modified sudoriferous (sweat)
glands that produce milk for the nourishment of offspring
Mammary ridges – the so called milk lines
In carnivores and the sow, the mammary gland develop
throughout the axillary to inguinal extent of the ridges, as is
appropriate for species that typically deliver multiple fetuses
In most domestic animals, only the inguinal mammary glands
develop, usually two (example mares, ewes and does) or
four (cows)
In the anthropoid apes and the elephant, only two pectoral
glands develop

18. EXAMPLE OF MAMMARY GLAND OF
SOME ANIMALS

19. STRUCTURE
 The mamma (pleural = mammae) is the glandular structure
associated with a papilla (teat) and may contain one or more duct
systems. The udder is a term designating all the mammae in the
ruminant and the mare (sometimes also used for the sow).
The lobes are the internal compartments of the mamma, separated
by adipose tissue. The lobes are divided into lobules, consisting of
connective tissue containing alveoli, which are clusters of milk
secreting cells. The lactiferous ducts are large ducts conveying
milk from the alveoli to the lactiferous sinus. The openings of the
lactiferous ducts convey milk formed in the alveolus to the gland
sinus.

20. STRUCTURE
The lactiferous sinus (milk sinus) is the milk storage
cavity within the teat and glandular body. The gland
sinus is part of the milk sinus within the glandular body
and the teat sinus is part of the milk sinus within the teat.

21. STRUCTURE
The teat is the projecting part of the mammary gland
containing part of the milk sinus. The papillary duct (teat
canal) is the canal leading from the teat sinus to the teat
opening and may be single or multiple. The ostium (teat
opening) is the opening of the papillary duct and the exit
point for milk or entrance point for bacteria.
The sphincter consists of muscular fibres surrounding
the teat opening that prevent milk flow except during
suckling or milking.

22. MAMMARY GLANDS OF THE COW
PARTS
- teat – a nipple of the mammary gland of a female
mammal
- ostium papillae – opening of teat canal
- papillary duct – narrow opening in the end of the teat
- lactiferous sinus – serve as reservoir for accumulated
milk in the mammary gland until it released at milking or
suckling via the teat sinus and teat canal
- gland cistern – large cavity within the quarter itself
- teat cistern – smaller cavity within the associated teat

23. SUSPENSORY APPARATUS
 MEDIAL LAMINAE – which take their
origin together from the linea alaba of
the abdominal wall and the symphysis
of the pelvis.
 LATERAL LAMINAE – composed
largely of dense white fibrous
connective tissue
 INTERMAMMARY GROOVE – divides
the left and right rows of mammae

25. BLOOD SUPPLY
Arteries
The main blood supply to the inguinal mammary glands is
from the external pudendal artery. This arises indirectly from
the external iliac artery via the deep femoral artery. The external
pudendal artery passes through the inguinal canal. In species
which also have thoracic and abdominal mammary
glands (bitch, queen, sow) additional blood supply is derived
from the internal thoracic artery and its branches - cranial
superficial epigastric arteries as well as from lateral
thoracic and intercostal arteries

26. BLOOD SUPPLY
 Veins
In most species thoracic and cranial abdominal mammary
glands drain via cranial superficial epigastric veins into the internal
thoracic vein. Caudal abdominal and inguinal mammary glands drain
via caudal superficial epigastric veins into the external pudendal vein.
In cattle a venous ring is formed between the base of the udder and
the abdominal wall. During the first pregnancy, an anastamosis develops
between cranial and caudal superficial epigastric veins forming
the subcutaneous abdominal vein (milk vein). As a result some drainage
from venous ring passes in a cranial direction via this vessel, which then
drains deeply through the abdominal wall (milk well) into the internal
thoracic vein. Other drainage passes to the external pudendal veins or to
perineal veins.

27. BLOOD SUPPLY

28. MAMMARY GLAND OF SWINE
 the normal number of teats in domestic hog is seven pairs,
or 14 teats
 sows average 2.5 more teats than the number of piglets in
their average litter
 glands that are underused dry up and do not develop again
until the next pregnancy
 inverted teats (concave nipples) and mastitis are the two of
the most common conditions adversely affecting the
mammary glands of sow

29. MAMMARY GLAND OF SWINE

30. MAMMARY GLAND OF SHEEPS AND GOATS

31. MAMMARY GLANDS OF THE HORSE

32. PHYSIOLOGY OF
LACTATION

33. COMPOSITION OF MILK
Milk contains all of the nutrients necessary for
survival and initial growth of mammalian neonates
The nutrients in milk include sources of energy (lipids
and carbohydrates), proteins to provide amino acids,
vitamins, minerals (ash) for electrolytes and water
The relative amounts of these nutrients in milk vary
among species
Diet and the stage of lactation also affect the
composition of milk

34. TYPICAL VALUES FOR CONSTITUENTS
OF MILK IN GRAMS PER LITER
SPECIES LIPIDS LACTOSE PROTEIN
TOTAL
MINERALS
(ASH)
CALCIUM
Cow 38 48 37 7.0 1.3
Mare 16 50 24 4.5 1.0
Ewe 70 40 60 8.0 1.9
Sow 80 46 58 8.5 2.0
Doe 40 45 35 7.8 1.2

35. MILK SECRETION
The epithelial cells lining the alveoli of
mammary glands are the cells primarily
responsible for the secretion of milk. The
appearance of these cells varies as they
synthesize and release the lipids, proteins,
and lactose of milk.
After the cells actively secrete the
constituents of milk and the lumen of the
alveoli are filled with milk, the epithelial
cells shrink and are described as a simple
low-cuboidal epithelium (Fig. 29-5). At this
stage, their secretory activity is relatively
low.

36. MILK SECRETION
Shortly after the stored milk is
removed, the epithelial cells increase
their secretory activity and begin to refill
the alveoli. Early in the secretory phase
the cells assume a more columnar
appearance and then gradually reduce
to cuboidal as milk fills the alveoli.
Small, apparently nonfunctioning alveoli
can be found in dry mammary glands,
and there is a relative increase in the
amount of interstitial loose connective
tissue (Fig. 29-4).

37. MILK SECRETION
Milk lipids are synthesized and packaged
into secretory droplets, which are extruded
from the luminal surface of the cell into the
alveoli (Fig. 29-6). As they are released, a
membrane covering derived from the cell
membrane of the epithelial cell encases the
lipid droplets. The alveolar secretory cells
also produce secretory vesicles that contain
both milk proteins (caseins) and lactose (Fig.
29-6). As caseins are synthesized and
packaged in these vesicles, they self-
aggregate into particles termed micelles.

38. MILK SECRETION

39. LACTOGENESIS
Is the establishment of milk secretion, and
galactopoiesis is the continued production of
milk by the mammary glands
Milk formation

40. GALACTOGENESIS
 The continuation of lactation requires stimuli to promote milk production and removal or
inhibition of stimuli that retard milk production. Stimulation of the nipples (teats) by either
milking or suckling elicits an abrupt increase in blood levels of prolactin. The increased
secretion of prolactin is the result of a neural reflex mediated through the hypothalamus
that regulates prolactin release from the adenohypophysis.
 The increase in prolactin is relatively short in duration (minutes to an hour). This periodic
and relatively brief surge of prolactin is essential to maintain normal lactation in most
species, but prolactin does not appear to be an essential regulator of lactation in cows.
Supplementation with prolactin does not increase milk secretion in cows, and lactation is
maintained in cows in spite of severe reductions in blood levels of prolactin.

41. MILK EJECTION OR LETDOWN
Milking or nursing alone can empty only the cisterns
and largest ducts of the udder. In fact, any negative pressure
causes the ducts to collapse and prevents emptying of the
alveoli and smaller ducts. Thus, the dam must take an active
although unconscious part in milking to force milk from the
alveoli into the cisterns. This is accomplished by active
contraction of the myoepithelial cells surrounding the alveoli
(milk ejection, or milk letdown).

42. MILK EJECTION OR LETDOWN
These myoepithelial cells contract when stimulated by
oxytocin, a hormone released from the neurohypophysis of
the pituitary as a result of a neuroendocrine reflex. The
afferent side of the reflex consists of sensory nerves from
the mammary glands, particularly the nipples or teats.
Afferent information reaches the hypothalamus, which
regulates the release of oxytocin from the neurohypophysis.

43. MILK EJECTION OR LETDOWN
Suckling the teats by the young is the usual
stimulus for the milk ejection reflex, but whether milk is
withdrawn from the teat or not, the milk ejection reflex
produces a measurable increase in the pressure of
milk within the cisterns of the udder.

45. COLOSTRUM
The first milk produced upon delivery of the newborn,
is important for the survival and vitality of new born
domestic animals
It contains a high concentration of immunoglobulins
produced by the immune system of the dam
Source of energy for the newborn, since most are
born with limited amounts of body fat and other
sources of metabolic energy

46. CESSATION OF LACTATION
The decline in milk production is associated with the
gradual decrease in the number of active alveoli and
an increase in the relative amount of connective
tissue

47. ..End of Presentation..
..Thank you..