Download Unit 2-Animal Genetics and Selection

The Basics
• What is a trait?
– Characteristics of an animal
• What is genetics?
– Branch of biology that deals
with the study of genes and
how traits are passed from
parent to offspring.
Through good selection strategies,
producers can improve the quality
of their animals over time by
making good decisions around
animal selection
What is a Breed?
Appaloosa
Suffolk
LaMancha
Hampshire
Brangus
Breed is a group of animals that through selection and
breeding share the same characteristics, which they pass on
to their offspring
Selecting for Desirable Traits
Cell
Basic Unit of All Life
Converts food to energy, waste is
disposed, proteins are made to build
and repair animal tissue, and genetic
material is stored and processed
Meiosis
Prophase I
Meiosis
Prophase II
Chromosome Pairs
Transmitting Genetics
Characteristics
• Inherited Traits
– Traits received from a parent
– Examples: color, size, growth
rate
• Fertility
– Ability of a male and female to
successfully fertilize an egg that
produces offspring
• Sterility
– An animal is unable to produce
an egg or sperm for
reproduction
• Delayed Breeding
– When an animal does not cycle
within the proper amount of
time for breeding
• Genotype
– animal’s genetic makeup
• Phenotype
– physical characteristics of an
organism
• Homozygous
– alike
• Heterozygous
– different
Color and Horn Inheritance
What are alleles?
Two parts to every gene expressed as either
capital or lower case letters such as “B” or “b”
Punnett Square
One-Trait
Punnett Square
Two-Traits
 The Results!
Abnormal Genetic Conditions
• Agnathia- lower jaw is several inches shorter than
upper jaw
• Bulldog- eye sockets that are large, nasal bones that
are short and broad, and broader forehead
• Cerebral hernia- opening in skull allowing brain tissue
to protrude
• Splay toe- ligament in the foot deteriorates making
toes spread
• Dwarfism- short-headed, short-legged, or pot-bellied
Abnormal Genetic Conditions
• Epilepsy- lowering of the head, chewing of the tongue,
foaming at the mouth, collapse into a coma
• Hairlessness- hairless over all or part of its body
• Hemophilia- blood does not coagulate or clot properly
• Lethal genes- genetic factors cause death of the young
• Porcine stress syndrome (PSS)- failure of the blood
circulation system
• Spider syndrome- bent forelimbs, “twisted spine,
angled rump in black-faced sheep.
Production Testing
Index - Used to compare an a animal’s
performance to other animals
Percent calf crop - percentage of female animals
that produced viable offspring
Expected Progeny Difference Records