ANIMAL REPRODUCTION
A. Male reproductive system – Bull or Ram
1. Scrotum – saclike part that contains testicles and the
epididymis; keeps temperature lower to keep animal fertile
2. Testicles – produce the sperm cells and the male hormone
testosterone
3. Epididymis – stores sperm cells while they mature
4. Vas deferens – passage way from epididymis to the urethra
5. Spermatic cord – protective sheath for vas deferens
6. Urethra – passageway for urine from the bladder and where
sperm from the epididymis is mixed with fluid from
accessory glands to form semen
7. Seminal vesicles – produces a fluid which protects and
transports the sperm
8. Prostate gland – produces a fluid that is mixed with a
seminal fluid.
9. Cowper’s gland – produces a fluid which cleans and
neutralizes the urethra ahead of the seminal fluid to help
protect the sperm
10. Penis – deposits the semen within the female reproductive
system
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11. Sigmoid flexure – extends the penis from the sheath
12. Sheath – tubular fold of skin
13. Retractor muscle – draws the penis back into the sheath
after copulation
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B. Female reproductive system – Cow or Ewe
1. Ovaries – produce the eggs within the follicles, produce the
female sex hormones estrogen and progesterone, and form
the corpus luteum
2. Infundibulum – funnel like end of oviduct closest to the
ovary
3. Oviducts (fallopian tubes) – carry the eggs from the ovaries
to the uterus
4. Uterus (womb) – place where the fetus grows; it has two
horns or branches
5. Cervix – is the neck of the uterus which separates the uterus
from the vagina
6. Vagina – passage between the cervix and the vulva; semen
is deposited here during copulation
7. Vulva – external opening of the reproductive and urinary
system
8. Clitoris – sensory and erectile organ of the female
C. Reproductive systems of poultry
 Male chicken
1. Testicles – produce the sperm and seminal fluid
2. Vas deferens – carry the seminal fluid and sperm cells to
the cloaca
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3. Cloaca – is enlarged part where the large intestine joins
the end of the alimentary canal
4. Alimentary canal – is the food-carrying passage which
begins at the mouth and ends at the vent
5. Papillae – is the organ in the wall of the cloaca that puts
the sperm cells into the hen’s reproductive tract
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 Female chicken
1. Ovary – produces the egg; only the left ovary and
oviduct produce eggs; the ova produced in the ovary
develop into egg yolks
2. Funnel – receives the yolk from the ovary and stores
sperm cells
3. Magnum – secretes the thick white of the egg (takes
about 3 hours)
4. Isthmus – two shell membranes are placed around the
yolk and thick white (takes about 1 hour & 15 minutes)
5. Uterus – the thin white and the outer shell are added here;
the egg remains in the uterus for about 20 hours
6. Vagina – the completed egg remains here for a short
period of time before being laid
D. Heat Period – time that the cow is receptive to the bull
 Signs of heat include:
1) Cattle, swine, and goats –
a) Trying to mount other animals and standing when
mounted by other animals
b) Nervousness and restless activity
c) Swelling of the vulva
d) Inflamed appearance around the lips of the vulva
e) Frequent urination
f) Mucus discharge from the vulva
2) Horses –
a) Relaxation of the vulva
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3)
b) Frequent urination
c) Teasing of other mares
d) Apparent desire for company
e) Slight mucus discharge from the vulva
Sheep – exhibit many of the same signs, but not quite as
visible as other species of livestock; are seasonal
breeders
E. Ovulation – release of egg from ovary
1. Before ovulation, the egg cell is contained in the follicle
that breaks open, releasing the egg.
2. The egg moves into one of the oviducts where if live sperm
is present, the egg may be fertilized.
3. Shortly after ovulation, the corpus luteum forms on the
ovary that releases the hormone progesterone. Progesterone
causes four things to happen:
a. The fertilized egg is implanted in the uterus
b. Other eggs are stopped from forming
c. The pregnant condition is maintained
d. The mammary glands begin to develop, which produce
milk to feed the young when they are born.
 If the egg is not fertilized, it does not grow. It
atrophies, or wastes away which allows another
follicle to grow and another heat period to occur.
F. Fertilization – is the union of the sperm and the egg cells
 During copulation, the male deposits sperm in the
reproductive tract of the female where the sperms move
through the tract until they reach the infundibulum.
 If an egg is present, a sperm cell may penetrate it.
 Only one sperm cell fertilizes an egg cell.
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 Sperm cells cannot live very long in the female reproductive
tract (24-30 hours in cattle).
 The egg cell lives about 12 hours after it is released if it is
not fertilized.
 For fertilization to occur, live sperm cells and the egg cell
must be present at the same time.
 If fertilization does not occur, the body absorbs the egg and
sperm cells. The estrus cycle will repeat itself until the
animal does become pregnant.
G. Gestation – is the time when an animal is pregnant and the
fetus is developing in the uterus.
 The fetus is connected to the placenta by the umbilical
cord.
 The placenta allows food, oxygen, and wastes to be
exchanged with the mother by the diffusion process.
 The fetus develops slowly in the first third of pregnancy
with the nervous system, head, and blood vessels
developing first followed by the bones and limbs.
 Average length of gestation:
1. Cattle – 281 days
2. Sheep – 148 days
3. Swine – 114 days (3 months, 3 weeks, & 3 days)
4. Goats – 151 days
5. Horses – 336 days
H. Parturition – is the process of giving birth to the new animal
 The corpus luteum reduces the production of
progesterone and there is an increase in the amount of
estrogen in the body.
 This causes the uterine muscles to contract which begins
the process of birth:
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1.
2.
3.
4.
5.
The first water bag gets larger and breaks
Shortly thereafter, the second water bag appears &
breaks open
Presentation of the fetus begins (front feet first,
followed by nose, then head, shoulders, middle, hips,
rear legs, and feet appear)
Young must receive colostrum (first milk) for first
12 to 14 hours
Several hours after birth the afterbirth (placenta) is
expelled from the uterus
I.
Reproduction in poultry is different than mammals in that the
young are not carried in the hen’s body, but instead develop in
the fertilized egg outside of the hen’s body. The process
involves the following steps:
1. The papillae in the cloacal wall of the male deposits the
sperm in the cloacal wall of the female.
2. The sperm moves up the oviduct to the funnel of the
oviduct where the egg is fertilized.
3. After the egg yolk is fertilized, it moves through the
reproductive tract of the female where the thick white,
shell membranes, thin white, and the shell are added.
4. After the egg is laid, the embryo grows inside the shell.
The embryo is fed by the contents of the egg during
development.
5. Incubation of eggs is keeping them at the proper
temperature and humidity for hatching (102 to 103
degrees F).
6. After incubation, the chicken hatches or breaks out of the
shell (21 days for chickens).
J. Cryptorchidism
 Is an inherited trait in males where one or both testicles are
held in the body cavity.
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 The animal is usually sterile if both testicles are in the body
cavity.
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