Colorado Agriscience Curriculum

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Colorado Agriscience Curriculum

• Animal Science
• Unit 4 Reproduction and Genetics
• Lesson 9 Fertilization, Pregnancy and
  Parturition

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Stages of Prenatal Growth

• Fertilization When the sperm and egg unite.
  When fertilization occurs, cell division occurs.
  It starts with 2, 4, 6, 8 and so on.
• Attachment The embryo that has gone through
  much cell division attaches itself to the uterus
  for further development.
• Embryonic Stage The period when body parts and
  organs start to form. The length of time differs
  between species
• Fetal Period Period that lasts until birth is
  mainly a time when body parts and organs mature.

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Gestation and Gestation Periods for Different
Species

• 1. Gestation Length of Pregnancy
• 2. Gestation time
• Human 253-303 Days
• Cow 285 Days
• Ewe 147 Days
• Mare 336 Days
• Sow 114 Days

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Gestation

• 3. The fetus develops in uterus, most of growth
  is in the last 1/3 of gestation.
• 4. Umbilical cord connects the navel to the
  placenta, where food, oxygen and wastes are
  exchanged.

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Parturition and Problems with Parturition

• Parturition Signals the end of gestation. The
  process is started by the release of cortisol.
  This release causes progesterone levels to
  decline and estrogen, prostaglandin, and oxytocin
  to increase. All these hormonal changes cause
  relaxation of the cervix and contractions to
  occur. These events allow for the fetus to be
  born outside the body.
• Abnormal positions (Dystocia) Piglets dont
  assume any particular position during birth and
  it doesnt seem to affect the ease of birth.
  However calves, lambs and foals may present
  themselves in abnormal positions. The next slide
  shows normal and abnormal positions.

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Normal Birth vs. Dystocia
Taylor, Robert E., Scientific Farm Animal
Production, 4th ed.
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Lambing The Birth Of Twins

• A pictorial study of parturition.

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The First Lamb

• This Suffolk ewe gave birth to twins.
• This is the first lamb to be born.
• She is licking it clean.

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• The lamb is yellow because of the amniotic fluid.

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The Wait for the New Lamb

• You can see the new lambs head.

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• The ewe is straining while the lamb is being
  born.
• Part of the new lambs body is showing.

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• Now the two lambs are born.
• They are ewe lambs.

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• The ewe is starting to lick the new lamb.

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• And licking.

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• And licking.
• The lamb is trying to stand.

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• The ewe lamb is looking for her first drink of
  colostrum.

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• Now she is standing.
• The afterbirth is being expelled.

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• Both lambs are standing and ready to find the
  ewes udder.

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• They have both nursed and are resting. Being
  born is tiring.