Which Stallion Should I Buy

1
Which Stallion Should I Buy?
Horse A
Horse B
2
Which Gilt Should My Friend Add to His Herd?
Gilt A
Gilt B
3
Introduction to Environmental and Agricultural
Sciences

• Animal Systems
• Genetics, Breeding,
• Reproduction

4
Technology in Animal Production

• Artificial Insemination
• Introducing the sperm to the egg
• by means other than natural mating
• Embryo Transfer
• Removal of a fertilized egg
• from a female and placing it
• in another female
• Genetic Engineering
• Movement of genes from one
• cell to another

5
Principles of Genetics

• Gregor Mendel father of genetics
• genes occur in pairs
• each parent contributes one of the pair
• only one gene is contained in the gamete
  reproductive cell.
• one trait will often be expressed in the pair of
  genes the dominant trait
• Black color in cattle
• White face color in cattle
• the trait that is masked in
• the pair is called recessive
• Red color in cattle
• Colored face in cattle

X

6
Cells and Cell Division

• Cells are the basis of all genetic activity.
• All plant and animal life begins as a single
  cell.
• Genes are located on the chromosomes within the
  nucleus of a cell.
• Mitosis results in duplication of the cell
  and growth of the animal. (pg. 559 in text)
• Meiosis occurs only during reproduction,
  causing the resulting offspring to inherit one
  gene controlling a certain trait from each
  parent. (also pg. 559 in text)

7
Genes

• Units of genetic material
• Responsible for all traits in an animal
• Occur at specific locations on chromosomes
• Chromosomes are composed of DNA (Deoxyribonucleic
  Acid)
• DNA the code of life
• Genes on chromosomes can be alike or different
• Alike homozygous
• BB or bb
• Different heterozygous
• Bb

8
Improving Animals Through Genetics

• People select animals who exhibit desirable
  traits.
• Through heritability, a of the trait is
  passed to the offspring.
• Heritability varies among traits (see figure 28-7
  on page 561 in text)

9
Genetic Engineering

• Genes have been linked to specific traits.
• Scientists can isolate the gene, remove it, and
  insert it into the cell of another animal.
• Has great potential for improved animals
• Disease resistance
• Increased growth and production
• Vaccines
• Cancer research
• Etc.

10
Genetics Terms

• Genotype
• genetic makeup of an organism
• BBPP
• BBPp
• BbPP
• BbPp
• BBpp
• Bbpp
• bbPP
• bbPp
• bbpp

• Phenotype
• the physical appearance of an organism as a
  result of its genotype
• Black, Polled
• Black, Horned
• Red, Polled
• Red, Horned

11
Genotype

• What will the offspring look like if we cross a
  heterozygous white-faced (Ww) bull with a
  homozygous colored-faced (ww) cow?
• A Punnett Square shows us that the offspring will
  have either the Ww or ww genotype.
• This genotypic ratio would be written as 22
• or 11.

W w
w w
But, what will the offspring look like?
12
Phenotype

• From the Punnett square, and
• the resulting genotypes, we can
• predict the probability of what
• the offspring will look like its
• phenotype from the cross
• given.

White face 2
Colored face 2
The phenotypic ratio is also 22 or 11 in this
cross.