Animal Genetics

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Animal Genetics

• by Ms. Jennifer Edge
• University of GA student
• GA Agriculture Education Curriculum Office
• July 2002

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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 animals
  phenotype.

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• Phenotypes are the physical appearance of the
  animal.
• Color
• Size
• Shape
• They can be caused by the environment.

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• The other reason for the animals 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.

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• An animals characteristics are passed on by its
  parents. It gets half of its genetic makeup from
  each parent.
• 50 from mother
• 50 from father

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• 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
  animals coat is made up of a pair of coat
  color genes-1 from father and 1 from mother.

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• 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

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• What happens if the fathers gene calls for a
  black coat and the mothers gene calls for a
  white coat?

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• 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

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The determination of the animals 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 females X.
• Therefore, male chromosomes decide the sex of
  animals.

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• If a white sow is mated to a black sow what would
  the offspring look like?

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• B represents the dominant black color gene.
• The w represents the recessive white color gene.

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• BB x ww

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• The pigs will be black, but will possess genes
  for both black and white color.

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• Bw x ww

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• Bw x Bw

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• Bw x BB

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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.

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EPD (Expected Progeny Difference)

• This is an estimate of the expected performance
  of an animals offspring.
• Producers look at EPDs to decide which bull to
  artificially inseminate their cows to.

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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

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EPDs

• All the EPDs are compared to the average for
  that breed.
• Example-
• If the average BW for an Angus bull is 3 and your
  bulls BW is 6 then it is expected that calves by
  your bull will be 3 lbs heavier than average.