Fertilization, Pregnancy, Parturition

TEKS: 130.3(C)(6)(A)

Objectives

2

Describe the process of reproduction and

development including fertilization;

Describe gestation period for several animals;

Define livestock parturition; and

Describe dystocia.

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Fertilization – When the sperm and egg

unite.

Attachment – The embryo attaches itself

to the uterus for further development.

Stages of Prenatal Growth

Stages of Prenatal Growth

4

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.

Gestation and Gestation Periods for

Different Species

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1. Gestation – Length of Pregnancy

2. Gestation time:

Human: 253-303 Days

Cow: 285 Days

Ewe: 147 Days

Mare: 336 Days

Sow: 114 Days

Gestation

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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.

Parturition

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Signals the end of gestation.

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.

Parturition and Problems with

Parturition

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Abnormal positions (Dystocia)

Piglets don’t assume any particular position during

birth and it doesn’t seem to affect the ease of birth.

However calves, lambs and foals may present

themselves in abnormal positions.

9 Taylor, Robert E., Scientific Farm Animal Production, 4th ed.

A pictorial study of parturition.

Lambing: The Birth Of Twins

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.

12

The Wait for the New Lamb

You can see the

new lamb’s

head.

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The ewe is

straining while

the lamb is

being born.

Part of the new

lamb’s body is

showing.

14

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. 17

And licking.

The lamb is trying to stand. 18

The ewe lamb is looking for her first drink of

colostrum.

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Now she is standing.

The afterbirth is being expelled. 20

Both lambs are standing and ready to find the ewe’s udder.

21

They have both nursed

and are resting.

Being born is tiring.

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