Animal Reproduction
Animal Science II
Unit 10
Objectives
• Identify and describe the male and female
reproductive organs
• Describe the function of the endocrine
glands and hormones in reproduction
• Describe the reproductive failures that may
occur
• Define: fertilization, gestation, parturition
and estrus cycle
Reproduction
• When organisms multiply or produce
offspring
• Sexual
• Asexual
Sexual Reproduction
• Union of male and female gametes or
copulation
• Fertilization occurs when the sperm
penetrates the egg cell
• Embryo or new animal begins to grow
• It is fed and protected in the female
reproductive tract until birth
• Parturition is the act of giving birth and the
final step in reproduction
Asexual Reproduction
• Does not involve the gametes
• Simple cell division in bacteria is an
example
Male Reproductive Organs
Male Poultry Reproductive Organs
Female Reproductive Tract
Female Poultry Reproductive Organs
• Fig 10-5 page 215
Ovulation Cycle
Before ovulation
begins the egg cell is
contained in the
follicle
If the egg is not
fertilized the corpus
luteum does not grow.
If the egg is fertilized
Corpus luteum forms
on the ovary
Follicle breaks open,
releasing the egg.
Egg moves into one of
the oviducts.
If live sperm are
present, it may be
fertilized.
Estrus Cycle
• Period of time in which the female will
accept the male for breeding
• Begins when the animal reaches breeding
age (see Table 10-1 p. 217)
• Cycle begins when a follicle on the ovary
begins to develop
• Estrogen is produced and cause the animal
to show the signs of estrus
Signs of Estrus
• See p. 216
If the egg is not
fertilized the corpus
luteum does not
grow , it waste away
allowing another
follicle to grow
Ovulation Cycle
Egg cell is
contained in
follicle
Corpus luteum forms
on the ovary shortly
after ovulation. It
releases the
hormone
progesterone
Fertilization
occurs if live
sperm are
present
Follicle breaks
open, releasing
the egg
Egg moves
into one of
the oviducts
Progesterone
• Causes four things to happen
– The fertilized egg (embryo) is implanted in the
uterus
– Other eggs are stopped from forming
– The pregnant condition is maintained
– The mammary glands begin to develop.
Several Offspring
• Fraternally Related
– Animals that have several young at one birth
– They each come from a different egg cell
• Identical
– Offspring that result from 1 egg splitting to
form two animals
Fertilization
• Union of the sperm and the egg cell
• Only 1 sperm fertilizes the egg cell
• Sperm do not live very long in the female
reproductive tract
– In cattle sperm live only about 24-30 hours
• Egg cells do not live very long either, only
about 12 hours if not fertilized
• Pregnancy will only occur if the sperm and egg
cell are present and alive at the same time
Gestation Period
• The time during which the animal is pregnant
• Fetus is surrounded by a watery enclosed in membranes
• Blood vessels in the umbilical cord supply nutrients and
oxygen and carry off waste
– Umbilical cord connects from the navel of the fetus to
placenta
• The placenta lies along the wall of the uterus-food,
oxygen and waste are exchanged with the mother
through a process called diffusion
• Fetus grows slowly—most growth occurs in the last 1/3
of the gestation period
– Early growth-head, nervous system, blood vessels
– Later-bones and limbs
Parturition
Second
water bag
appears, this
contains the
fetus
Presentation of the fetus
begins
The birthing
process
begins
1st Water bag appears, gets
larger and breaks
Increase in
the amount
of estrogen
produced
Uterine muscle
contractions begin
Corpus luteum reduces
production of progesterone
• The process of giving birth
Normal
presentation
will vary
with species
Birth
• Umbilical cord is broken, this causes the
animal to breathe
• Progesterone has stimulated the mammary
glands, so the mother will have milk for the
young animal to nurse
• The first milk, called colostrum is very
important because it is rich in antibodies,
vitamin and minerals needed by the young
animal
– It is important the young animal receive colostrum
milk during the 1st 12-24 hours of life
After Birth
• Afterbirth is expelled from the uterus several
hours after the birth
– Afterbirth consist of placenta and other
membranes that were not expelled when the fetus
was born
• If not expelled it will decay inside the uterus
causing infection
• Care must be taken to prevent infection when
removing the afterbirth from the uterus—if
not the animal may become sterile.
Reproduction in Poultry
• Read p. 219-220
Reproductive Failures
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Physical Condition
Nutrition
Exercise
Disease/Infection
Hormone levels/balances
Cysts
– A swelling containing fluid or semisolid substance.
– May occur in the reproductive organs
• Other Unknown reasons
Summary
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Mating of male and female animals begins the process of reproduction
Female gamete is called an ovum or egg
Male gamete is called the sperm
Sperm are deposited in the female reproductive tract where they move to the
oviduct and fertilize the egg cell
Females have an estrus or heat cycle during which she will accept a male for
mating
An egg cell is released during the heat period, if fertilized it moves to the
uterus where it grows into a fetus
Hormones control the release of egg cells and maintain pregnancy in the
animal
When the fetus reaches the right time for birth, the uterine muscles contract,
forcing the fetus through the birth canal
Reproduction in poultry is similar to mammals—the main difference is that
they embryo develops in the eggshell outside the mothers body
Eggs must be kept the proper temperature and humidity to hatch—this is
usually done with an incubator