Download ANIMAL GENETICS

Animal Genetics
by Ms. Jennifer Edge
 University of GA student


GA Agriculture Education Curriculum Office
 July 2002
ANIMAL GENETICS
Differences in animals are brought
about by 2 groups of factors: genetic
and environmental factors.
 One set of differences is said to be the
animal’s phenotype.


Phenotypes are the physical
appearance of the animal.
– Color
– Size
– Shape
They can be caused by the environment.
The other reason for the animal’s
phenotype is the genotype or the actual
genetic makeup of the animal.
 The only way to control genotype is to
control the type of animals used for
breeding.

An animal’s characteristics are passed
on by its parents. It gets half of its
genetic makeup from each parent.
 50% from mother
 50% from father


Every gene from the male is paired with
the same type of gene from the female.
– Example: The gene that controls the color
of the animal’s coat is made up of a pair of
“coat color” genes-1 from father and 1 from
mother.
If both genes are the same,that is they
both call for a black coat or both call for
a white coat, then the genes are said to
be homozygous. The animal will be that
color.
 Example: BB is homozygous black


What happens if the father’s gene calls
for a black coat and the mother’s gene
calls for a white coat?
In this case the genes of the offspring
are said to be heterozygous.
 The color will then be determined by the
dominant gene.
 Example: Bw is heterozygous Black

The determination of the animal’s
sex

Each body cell contains one pair of
chromosomes called the sex chromosomes.
 The female chromosome is referred to as XX.
 The male chromosome is XY. When the male
is divided into sperm it contains either X or Y
to meet the female’s X.
 Therefore, male chromosomes decide the
sex of animals.

If a white sow is mated to a black sow
what would the offspring look like?
“B” represents the dominant black color
gene.
 The “w” represents the recessive white
color gene.


BB
x
ww

The pigs will be black, but will possess
genes for both black and white color.

Bw
x
ww

Bw
x
Bw

Bw
x
BB
Performance Data

An animals performance and analysis of
ancestry and progeny are valuable tools
in determining the animals use for
breeding. This information is obtained
through the use of data collection and
computer analysis.
EPD (Expected Progeny
Difference)

This is an estimate of the expected
performance of an animal’s offspring.

Producers look at EPD’s to decide
which bull to artificially inseminate their
cows to.
Explanation of Performance
Records
BW(Birth Weight)-birth weight expected
 WWT(Weaning Weight)-weaning weight
at 205 days of age
 YWT(Yearling Weight)-yearling weight
at 365 days of age

EPD’s

All the EPD’s are compared to the
average for that breed.

Example– If the average BW for an Angus bull is 3
and your bull’s BW is 6 then it is expected
that calves by your bull will be 3 lbs heavier
than average.