Unit B3-1

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Unit B3-1

• Animal Science

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Problem Area 3

• Animal Reproduction

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Lesson 1

• Artificial Insemination

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Student Learning Objectives

• 1. Describe the importance of animal
  reproduction.
• 2. List the parts and explain the functions of
  female and male reproductive systems.
• 3. List and describe the phases of the estrous
  cycle.
• 4. Explain how artificial insemination is
  performed.
• 5. Explain the advantages and limitations of
  artificial insemination.
• 6. Explain new technologies that are being used
  in reproductive management of animals.

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Terms

• anestrus
• artificial insemination
• cervix
• cloning
• copulation
• cowpers gland
• diestrus
• egg
• ejaculation
• embryo

• embryo transfer
• estrous cycle
• estrous synchronization
• estrus
• fertilization
• fetus
• genetic engineering
• gestation
• heat
• insemination

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Terms cont.

• metestrus
• natural insemination
• ovary
• oviduct
• ovulation
• parturition
• penis
• proestrus
• prostrate gland
• reproduction

• scrotum
• semen
• seminal glands
• seminal vesicles
• sexed semen
• sexual reproduction
• sperm
• sperm ducts
• superovulated

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Terms cont.

• testicles
• urethra
• uterus
• vagina
• vulva

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Why is reproduction important? What is the
process of animal reproduction?

• Reproduction is the process by which animals
  produce offspring. Reproductive decisions are
  some of the most critical management decisions
  that a producer makes.
• Whether someone is managing a 400 cow beef herd
  or raising guinea pigs for a local pet supply
  store lack of understanding the reproductive
  process can cost producers a significant amount
  of time, money, and other resources.
• The ability to reproduce is one of the basic
  characteristics of a living thing in order for a
  species to continue they must be able to produce
  viable offspring.

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• A. Only animals within a species can produce
  fertile offspring. Offspring have similar traits
  of their parents. A horse and a donkey are two
  different species that can reproduce. However,
  they produce a mule which is sterile.
• 1. Parents are selected and mated to achieve
  certain goals with offspring such as producing
  offspring with high milk productivity, large
  litters, or meaty carcasses.
• 2. Reproduction results in new animals that are
  raised for the products they produce. Examples of
  products include meat, eggs, milk, wool, and pets.

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• B. Most animals are produced with sexual
  reproduction. Sexual reproduction is the union of
  the sperm and the egg. Two parents are required.
  Asexual reproduction requires only one parent
  offspring are genetically identical to the
  parent. Bacteria and other one-celled organisms
  reproduce through asexual reproduction.
• 1. Sperm is the sex cell of male animals. They
  are produced in the testes.
• 2. The egg or ovum is the sex cell of female
  animals. They are produced in the ovaries.

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• C. Fertilization is the process by which the
  union of a sperm and an egg occurs. It is also
  known as conception. Conception takes place in
  the females reproductive tract for dogs, cattle,
  hogs, and many other animals. Fertilization
  occurs outside of the body for organisms such as
  fish.
• 1. The process of placing sperm in the
  reproductive tract of the female is known as
  insemination.

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• 2. Natural insemination occurs when a male of a
  species mates with a female of the same species.
  Sperm are placed in the female reproductive tract
  by the male during copulation.
• a. Copulation is the mating process in which
  sperm are ejaculated from the penis of the male
  in the vagina of the female. Producers often
  refer to this as breeding.
• b. Females must be receptive to males at a time
  in the estrus cycle known as heat.

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• 3. Artificial insemination (AI) is used in some
  situations, such as with dairy and beef cows,
  horses, and others. Artificial insemination
  involves placing semen collected from a male in
  the female reproductive tract using equipment
  designed for the purpose. AI is a key management
  tool for producers that allows them to have
  greater choices in selecting beneficial traits
  for improved genetic performance.

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• D. Once an egg has been fertilized, it becomes an
  embryo that attaches itself to the uterine wall
  for nourishment. This state of pregnancy is
  referred to as gestation. Gestation varies
  greatly between species and can last form a few
  weeks to over a year.
• 1. The embryo goes through a time of development
  and becomes a fetus. The fetus develops to a
  stage where it is born and can live outside the
  uterus.
• 2. Parturition is the act of giving birth and is
  the final stage of the reproductive process.

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What are the major parts of female and male
reproductive systems?What are the functions of
the parts?

• A. The reproductive system of the female is
  designed to produce eggs, make conception
  possible, and promote development of the
  embryo/fetus until birth. The major parts of the
  system are
• 1. The vulva is the external part of the female
  reproductive and urinary tracts. Inside the vulva
  is the clitoris which is the sensory organ of the
  female.
• 2. The vagina is the mating organ of the female.
  It receives semen (sperm cells) from the male and
  serves as the canal through which the fetus moves
  during birth.
• 3. The cervix is the entrance to the uterus.

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• 4. The uterus is the organ in which the embryo
  and fetus develop. The uterus is Y-shaped. It
  contains the cervix and two uterine horns.
  Females that usually have only one offspring at a
  time such as a cow have small uterine horns and a
  large uterine body. Organisms such as sows that
  have large litters, have a small uterine body and
  large uterine horns.
• 5. The oviduct (also known as the fallopian tube)
  is a tube leading from the ovaries to the uterus.
  Fertilization usually takes place near the upper
  end of the oviduct. After fertilization, the
  zygote travels to the uterus for implantation.
  There are two oviducts one for each ovary.
• 6. The ovary is the organ that produces the eggs
  or ova. Eggs pass from the ovary into the
  oviduct.
• a. When the egg is releases from the ovary, it is
  referred to as ovulation.

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• B. The reproductive system of the male is
  designed to produce and store sperm and to
  deposit them in the reproductive tract of the
  female of the species. The major parts are listed
  below.
• 1. The penis is the male reproductive organ that
  deposits semen in the reproductive tract of the
  female.
• a. Semen is a fluid containing sperm secreted by
  the seminal and prostate glands.
• b. Semen is expelled by a process known as
  ejaculation. Sexual stimulation during the mating
  process is needed for ejaculation to occur.
• c. The retractor muscle and the sigmoid flexure
  (bulls, boars, and rams) causes the penis to
  extend and return from the sheath.

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• 2. The urethra is the tube that extends through
  the penis from the urinary bladder.
• 3. The seminal glands produce fluids that promote
  the production of viable sperm.
• 4. The seminal vesicles are organs attached to
  the urethra and produce a fluid that nourishes
  sperm.
• 5. The prostate gland is an organ located around
  a section of the urethra and produces a fluid
  that becomes part of the semen.
• 6. The cowpers gland creates a fluid that moves
  through the urethra prior to ejaculation cleaning
  and neutralizing the area ahead of the semen.
• 7. The sperm ducts are tubes that connect the
  urethra with the testicles. They carry sperm from
  the testicles and mix with fluids to form semen.

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• 8. The testicles are the male organs that produce
  sperm. They are outside the body cavity and are
  carried in the scrotum. If the testicles are
  inside the body cavity, the animal is sterile.
  This is commonly referred to as cryptorchidism.
  Testosterone, a hormone, is produced in the
  testicles.
• 9. The scrotum is a pouch-like skin structure
  that holds the testicles outside the body. The
  temperature in the scrotum is slightly lower than
  that of the body this pro-motes sperm
  production.
• C. The female and male reproductive systems are
  designed to assure efficient reproduction
  processes. This is needed in animal production
  systems where animals are produced and used for
  specific purposes.

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What are the phases of the estrous cycle? How are
these related to reproduction?

• The estrous cycle is a series of steps that occur
  from estrus to estrus. These are the phases of
  reproductive readiness in the reproductive system
  of a mature female. The cycle does not occur
  during pregnancy nor when a female is in
  anestrus. Anestrus is the absence of cycling.
  Anestrus may occur due to disease, not being of
  reproductive age, or other conditions.

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• A. The estrous cycle is comprised of four phases.
  The phases occur in a definite sequence unless
  the female is pregnant. (The sequence listed here
  is the sequence of occurrence.)
• 1. Estrus is the phase when a female is in heat.
  The animal is receptive to mating and will stand
  for copulation with a male. Females exhibit signs
  of heat. An enlarged vulva, restlessness, and a
  mucus discharge are signs. Some females exhibit
  behaviors indicating readiness for mating such as
  when a cow mounts another cow in the mating
  position. Ewes, sows, mares, and some small
  animals ovulate at this time. Some animals
  usually release only one egg while others may
  release twenty eggs at one time.

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• 2. Metestrus is the phase following heat.
  Ovulation occurs during metestrus in does and
  cows as do other processes that help maintain a
  pregnancy should conception occur. During
  metestrus luteinizing hormone (LH) causes the
  corpus lutea (CL) to develop.
• 3. Diestrus is the phase in the estrous cycle
  when the reproductive system assumes that
  conception has occurred, even if it has not.
  Diestrus is several days long depending on the
  species of animal. High levels of progesterone
  cause the uterus to begin preparing for pregnancy.

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• 4. Proestrus is the period following diestrus in
  which preparation is being made by the
  reproductive system for the next heat period and
  ovulation. If conception has occurred, the
  estrous cycle ceases until it is renewed after
  gestation and parturition.
• B. The following table outlines the length of
  estrous, length of estrus, and when ovulation
  occurs for a variety of species.

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• C. Animal producers can be more efficient in
  animal reproductive management if they know the
  phases of estrous. Careful observation by a
  trained producer and records on reproductive
  cycles will promote breeding to assure the
  production of young animals at the best time.
• For example, cattle producers often breed cows to
  assure calving in the spring when pasture grasses
  are beginning to grow or in the fall when the
  weather is favorable. This allows a cow to
  produce maximum milk for the nutrition and growth
  of the calf.

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How is artificial insemination performed?

• A. First the semen must be collected.
• 1. An artificial vagina is used with bulls,
  stallions, boars, bucks (rabbits), and rams to
  collect the semen. An artificial vagina is about
  1014 inches long for bulls and about 2.5 inches
  across. The outside of the tube is hard with a
  soft rubbery lining inside. Warm water is placed
  between these two linings. A dummy or other
  animal is used for the male to mount. The penis
  is then directed into the artificial vagina and
  the semen is collected. Some animals require the
  use of an electroejaculator.

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• 2. Tomturkeys and roosters require manual
  stimulation. Gentle pressure on the abdomen of
  fish will yield semen.
• 3. One ejaculation from a bull contains about 5cc
  of semen this is enough to breed about 500 cows.
  A stallion will produce enough to breed only
  about 17 mares in one ejaculation.
• 4. The semen is evaluated after being collected
  to ensure good quality.
• 5. It is then cooled slowly. The sperm will die
  if they are cooled quickly.

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• 6. Extenders such as egg yolk, antibacterial
  agents, and other material to add volume to the
  semen are added.
• 7. The semen can be stored at 41 F (5 C) for
  about one week or it is stored at -320 F (-196
  C) in liquid nitrogen. It can later be thawed for
  use. Semen frozen in liquid nitrogen can last up
  to 40 years. Liquid nitrogen tanks are used to
  transport semen and for storage on the farm.

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• B. Detecting estrus is key to successful
  artificial insemination.
• 1. Standing heat is one of best indicators of
  estrus in cows. Cows will stand to be mounted and
  will try to mount other cows. They will be
  restless and will oftentimes have an enlarged
  vulva and discharge.
• 2. Mares will wink to expose their clitoris and
  will urinate frequently.
• 3. Redness in the vulva is an indicator for sows.
• 4. Ewes will not show signs of estrus until a ram
  is present. Producers will use a castrated ram to
  detect heat.
• 5. Goats will act aggressively, be noisy and
  active, stand to be mounted, and have a mucous
  discharge.

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• C. The timing of insemination varies greatly by
  species and can vary between individuals to a
  degree.
• 1. Cows are usually inseminating in the evening
  after showing signs of estrus in the morning or
  in the morning after showing signs the evening
  before.
• 2. Mares are usually inseminated on the third,
  fifth, and seventh days of estrus.
• 3. Turkeys are inseminated three times over the
  course of several weeks. About one week should
  pass between the first two inseminations and then
  a little over a week between the second and third
  inseminations. A female turkey has a storage
  gland for semen making this possible.
• 4. Twenty-four hours after the initiation of
  estrus sows can be inseminated. Some producers
  will inseminate the sow after another 24 hour
  period.

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• D. Restrain the animal in a stall or stanchion.
• E. Assemble the wide array of equipment and
  supplies that are needed.
• 1. liquid nitrogen tank to store the semen straws
• 2. straw of semen
• 3. straw tweezers
• 4. sterile lubricant (non-spermicidal) to put on
  the plastic sleeve and/or the animals vulva
• 5. insemination gun to hold the straw and
  maneuver it through the cervix
• 6. thaw box to thaw the straw of semen
• 7. paper towels to keep the area clean,
  especially the animal.

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• 8. scissors to cut the end of the straw just
  prior to insemination
• 9. thermometer to measure the temperature of the
  water bath
• 10. plastic glove or sleeve to put on the
  inseminators arms
• 11. cover sheath
• F. Cows are artificially inseminated using the
  recto-vaginal method.
• 1. Carefully remove the straw of semen from the
  liquid nitrogen tank using the tweezers. Be
  cautious to not burn your fingers.
• 2. All semen must be thawed before use. Usually a
  straw is placed in a warm water bath (9598 F or
  3334 C). Thaw the straw following the
  recommendations from the company where the semen
  was purchased.

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• 3. Using a paper towel dry the straw thoroughly.
• 4. Pull the plunger on the inseminating gun back
  about 46 inches.
• 5. Insert the straw and cut the end off.
• 6. Place the cover sheath over the end of the gun
  and secure.
• 7. Hold the inseminating gun either in your mouth
  or have someone else hold it for you.
• 8. Lubricate the glove with the non-spermicidal
  lubricant.
• 9. Insert the gloved arm into the vulva and clean
  out the rectum.
• 10. Clean the vulva with the paper towels.
• 11. Locate the cervix.
• 12. Using the other hand carefully insert the
  inseminating gun upward into the vulva to avoid
  injury.

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• 13. Slide the inseminating gun through the
  cervix.
• 14. Deposit the semen into the uterus by pushing
  the plunger.
• 15. Slowly remove the inseminating gun.
• 16. Record the breeding information
• G. Placement and method of insemination also vary
  between species.
• 1. Instead of inserting the arm into the rectum
  or mares, it is inserted into the vagina because
  they have a more delicate rectum. The semen is
  also deposited into the uterus.
• 2. An inseminating tube is placed through the
  cervix of a sow and a plastic squeeze bottle is
  used to insert the semen.

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What are the advantages and limitations of
artificial insemination?

• A. There are many advantages to breeding animals
  artificially.
• 1. Maximum use is made of outstanding sires.
  Semen can be used after the sire has died or can
  be shipped anywhere in the world.
• 2. Uniformity of offspring is increased.
• 3. Certain physical handicaps to mating may be
  overcome.
• 4. Sire cost can be reduced.
• 5. Danger and cost of keeping a sire is
  eliminated.
• 6. Cost and delays involved in using infertile
  sire are reduced.
• 7. Better health is maintained.
• 8. Breeding herd records are improved.
• 9. Profits are increased.
• 10. Pride of ownership is increased.

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• B. Artificial insemination also has several
  limitations.
• 1. Skilled technicians are required.
• 2. Physiological principles must be followed.
• 3. Sire market may be limited.
• 4. Diseases may be spread.
• 5. May be subject to certain abuses.
• 6. May accentuate the damage of a poor sire.
• 7. Artificial breeding organizations require
  large investments of capital and competent
  management.

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What new technologies are being utilized to
manage the reproductive success of animals?

• Many new technologies are available today for
  producers to consider in optimizing their
  reproductive program and many more are being
  developed.
• A. Producers now have the ability to use sexed
  semen. Sexed semen is semen that contains only
  all male or all female sperm. There is only about
  a 90 chance that the preferred sex will be
  produced and the cost of the semen is much higher.

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• B. Estrous synchronization is commonly used
  especially in the cattle and sheep industries.
  Estrous synchronization is when producers
  manipulate the cycles of animals to bring a group
  into heat at the same time. This can be used to
  ensure the detection of heat, uniform calving or
  lambing time, and uniform breeding time.
• 1. Several different drugs can be used and the
  timing of shots varies. Generally, prostaglandin,
  progestin, or both are used. Prostaglandin causes
  progesterone production to stop this causes
  estrus to occur. Progestin keeps progesterone
  levels high so that the animal stays in diestrus
  for a longer period of time.
• 2. Sheep breeders use controlled internal drug
  releasers (CIDR) to synchronize ewes. The CIDR is
  placed into the vagina and then removed. This
  causes them to cycle and can help fertilization
  to occur during a time of the year when they are
  not normally cycling.

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• C. When an animal with outstanding genetics is
  found, a process known as embryo transfer (ET)
  can be used. With ET, the donor is superovulated
  a large number of eggs are released due to the
  application of certain drugs.
• Fertilization occurs and the fertilized eggs are
  harvested either surgically or non-surgically.
  The embryos are then transferred to a recipient
  or surrogate mother where the embryo develops.
  The surrogate mother is usually of less value
  than the donor. Embryos can also be frozen in
  liquid nitrogen for implantation later, but this
  is generally not as successful.

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• D. Cloning is one of the newest reproductive
  management tools available. Through cloning
  multiple exact genetic copies of an animal are
  produced.
• 1. Scientists can clone animals by letting the
  embryo develop to the 32 cell stage and then
  split the cells apart. This is similar to how
  identical twins are created in nature. Thousands
  of clones could be created at one time using this
  process.
• 2. Scientists can also take a cell from an adult
  animal and produce a new cloned off-spring. This
  was the process that was used to create Dolly the
  sheep.
• 3. Scientists have also created cattle by taking
  primordial germ cells during the development of
  the fetus.
• E. Genetic engineering is the manipulation of the
  genes of an organism by adding, removing, or
  modifying the DNA. This is usually most
  successful prior to fertilization.

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Review/Summary

• Why is reproduction important? What is the
  process of animal reproduction?
• What are the major parts of female and male
  reproductive systems? What are the functions of
  the parts?
• What are the phases of the estrous cycle? How are
  these related to reproduction?
• How is artificial insemination performed?
• What are the advantages and limitations of
  artificial insemination?
• What new technologies are being utilized to
  manage the reproductive success of animals?