Colorado Agriscience Curriculum
Section
Animal Science
Unit
Unit 7: Animal Behavior and Environment
Lesson Title
Lesson 4: Evolution of Livestock Breeds
Agricultural Education Standards
Standard AGS 11/12.3 The student will demonstrate an understanding of physiological
processes in agriculturally important animals.
Enabler AGS 11/12.7.4 Understand the evolution and formation of livestock
breeds.
Science Standards
Standard SCI 3.0 Life Sciences: Students know and understand the characteristics and
structure of living things, processes of life, and how living things interact with each other
and their environment.
Competency SCI 3.1 Students know and understand the characteristics of living
things, the diversity of life, and how things interact with each other and with the
environment.
Competency SCI 3.13 Explain how adaptations of an organism determine its
niche in the environment.
Competency SCI 3.14 Explain how changes in an ecosystem can affect
biodiversity and biodiversity contributes to an ecosystem’s stability.
Competency SCI 3.40 Students know and understand how organisms change over
time in terms of biological evolution and genetics.
Competency SCI 3.42 Give examples to show how some traits can be inherited
while others are due to the interaction of genes and the environment.
Competency SCI 3.44 Describe how mutation, natural selection and reproductive
isolation can lead to new species and explain the planet’s biodiversity.
Competency SCI 3.45 Explain why variation within a population improves the
chances that the species will survive under new environmental conditions.
Unit 7, Lesson 4: Evolution of Livestock Breeds
1
Student Learning Objectives (Enablers)
As a result of this lesson, the student will …
1. Students will be able to define key words such as breed, adaptation, evolution, niche,
mutation, natural selection, and reproductive isolation.
2. Students will be able to read a short history of a breed and determine the adaptive
traits, important characteristics and summarize the reproductive selection that has
taken place.
3. Students will understand the value of biodiversity in livestock breeds.
Time Instruction time for this lesson: 50 minutes.
Resources




Scientific Farm Animal Production, Fourth Edition, Robert E. Taylor
http://www.ansi.okstate.edu/breeds/
http://teacher.scholastic.com/dirtrep/animal/invest.htm
Biology: The Dynamics of Life Textbook
Tools, Equipment, and Supplies
 Powerpoint Presentation and means for viewing it.
 Powerpoint Presentation Notes Worksheets
 Internet Worksheets / Computers or Printed Information
 Blank paper, colored pencils / markers / crayons, etc.
Key Terms The following terms are presented in this lesson and appear in bold italics:
Breed, adaptation, niche, mutation, natural selection, reproductive isolation.
Interest Approach
(Ask the following questions quickly, without waiting for answers. They are meant to get
students focused on the topic.) Did you know there are over 200 breeds of horses? And
more than 250 breeds of cattle recognized around the world? Why are there so many
different breeds? How were they created? Will we continue to create more breeds?
These are all questions that we could spend all day discussing. Today, we are going to
start with understanding what a breed is. Then we’ll take a look at some of the scientific
as well as social selection that has gone on throughout history to create such a wide
variety of breeds of livestock. We’ll begin by taking a few notes from a PowerPoint
presentation, then finish with you doing your own research about some breeds you’ve
never heard of before.
Unit 7, Lesson 4: Evolution of Livestock Breeds
2
Summary of Content and Teaching Strategies
Objective 1. Students will be able to define key words such as breed, adaptation,
evolution, niche, mutation, natural selection, and reproductive isolation.
Students should take notes on the worksheet as they follow along with the PowerPoint
presentation that follows. The words and ideas highlighted in green should be recorded
in the worksheet.
Slide #2
I.
What is a breed?
A.
Animals that, through selection and breeding, have come to resemble one another
and pass those traits uniformly to their offspring.
1.
Unfortunately this definition leaves some unanswered questions. For
example, when is a crossbred animal considered a composite breed and
when do we stop thinking about them as composites? The Genetics of
Populations by Jay L. Lush helps explain why a good definition of "breed"
is elusive.
a.
A breed is a group of domestic animals, termed such by common
consent of the breeders, ... a term which arose among breeders of
livestock, created one might say, for their own use, and no one is
warranted in assigning to this word a scientific definition and in
calling the breeders wrong when they deviate from the formulated
definition. It is their word and the breeder’s common usage is what
we must accept as the correct definition.
2.
Dr. Lush's definition helps us understand that it is at least in
part
the perception of the breeders and the livestock industry which decides
when a group of individuals constitutes a "breed".
Slide #3
I.
What is a breed?
B. Breeds are primarily distinguished by visual characteristics: color, pattern, polled or
horned condition, or extreme differences in form and shape.
1. Composite or synthetic breeds: new breeds being developed that combine the
desirable characteristics of several existing breeds.
2. Purebred: purity of ancestry; only animals in that particular breed have been
mated to produce the animal in question.
Slide #4
II.
Breed Development
A. The development or evolution of breeds can take different routes.
Unit 7, Lesson 4: Evolution of Livestock Breeds
3
1. Sometimes, change that can occur as the result of selection for a small number
of traits
a. Holstein cattle have been selected primarily for milk production and
are the highest milk producing cattle in the world.
b. The Bedouins of the desert developed Arabian horses with strength,
courage and stamina required for survival, and for the speed and
responsiveness needed to win the tribal skirmishes.
Slide #5
2.
Other breeds have traits that result from natural selection pressure based
upon the environment in which they were developed.
a. N’dama cattle from west Africa have, through the centuries,
developed a resistance to trypanosomiasis or sleeping sickness
spread by the tse-tse fly, which is fatal to most other breeds of
cattle.
Slide #5
b. The Chincoteague Pony, descended from the feral horses on a
barrier island off the coast of Maryland and Virginia. 80% of their
diet is coarse saltmarsh cordgrass and American beachgrass; their
diet also includes poison ivy. The high concentration of salt in
their diets causes the horses to drink twice as much fresh water as
domestic horses and have a "bloated" appearance.
Slide #6
B.
Adaptations of an animal determine its niche in the environment.
1. Adaptation: evolution of structural, internal, or behavioral features that help an
organism better survive in an environment.
a.
The large eyes of nocturnal animals.
2. Niche: the role of a particular species in a community regarding food, space,
reproduction, etc.
Slide #7
3.
Slide #8
C.
Structure and Behavior Determine Environment
a. Structure
1. Sharks have characteristics that enable them to survive in water,
a streamlined body design and teeth that re-grow to replace
broken ones.
2. The artic fox’s coat changes color for camouflage.
b. Behavior
1. Bears survive a long, cold winter by hibernating.
2. Pigs are difficult to herd and move long distances, so they are used
mostly in farming communities.
Livestock has evolved over time through genetic changes that are both natural and
selected by man.
1. Mutation: random error or change in the DNA sequence that may effect whole
chromosome or one gene.
Unit 7, Lesson 4: Evolution of Livestock Breeds
4
a. This usually results in a negative result.
2. Natural Selection: a mechanism that explains how populations evolve; organisms
with favorable variations survive.
a. The Romney breed of sheep respond to it’s geographic and climatic conditions
with hooves that are resistant to foot rot and fleeces that remain healthy in
harsh weather.
Slide #9
D.
3. Reproductive Isolation: occurs when organisms that formerly interbred are
prevented from producing offspring.
a. By developing different mating times.
b. By geographic factors
c. This is often induced by man.
All these factors can lead to a new breed or even a new species
Slide #10
III.
Why is biodiversity important?
A. Why are we concerned about preserving information about minor, or relatively
unknown, breeds of livestock? (Discuss bioterrorism possibilities, genetic disorders,
environment changes, etc.)
Slide #11
1. Holstein cow example
a. Holstein has advantage over other breeds in the production of whole milk,
this advantage is based on feeding high levels of cereal grains and pricing
that favors low milk-solids content.
b. The Dutch Belted breed displayed excellent milking ability in a grassbased dairy situation in trials in the early 1900's and would be more
preferable if cereal grains weren’t available.
c. In Australia, composite breeds, such as the Australian Friesian Sahiwal,
have been developed which have higher milk production levels than
Holsteins in the tropical regions of that country.
Slide #12
2. Natural resistance to diseases or parasites example
a. Some breeds of sheep have a natural resistance to internal parasites.
Should vaccines become restricted or uneconomical then a breed such as
the critically endangered Gulf Coast Native, with the parasite resistance it
has developed through natural selection, could be of critical importance in
the sheep industry.
Slide #13
B.
Genetic diversity should be maintained to help meet the potential challenge
resulting from changes in production resources and market requirements.
Unit 7, Lesson 4: Evolution of Livestock Breeds
5
Objective 2. Students will be able to read a short history of a breed and determine the
adaptive traits, important characteristics and summarize the reproductive
selection that has taken place.
As directed on slide #14, give students directions for completing the internet worksheet. If an
internet connection is not available for each student, you could print off breed pages ahead of
time and hand them out. Try to make sure there are an equal number of students looking up
breeds for cattle, goats, horses, sheep, swine and other livestock. This will provide optimum
variety. It should only take each student about 10 minutes on the computer to look up the
information.
Slide #14
Students: now, it’s your turn to research!
• As is states on your worksheet, you should visit this website:
http://www.ansi.okstate.edu/breeds/
• Click on the species assigned to you by your instructor: cattle, goats, horses, sheep,
swine, or other
• Click on a breed you have never heard of before and answer the questions on your
worksheet as they relate to that breed.
– If you pick a breed that does not answer most of the questions, switch to a
different breed.
• Be prepared to tell the class about the information you find.
After the class has all completed the assignment, have a few volunteer to share the breed they
looked up, and the adaptive traits as well as important characteristics it has.
Objective 3. Students will understand the value of biodiversity in livestock breeds.
You can see from the research you have done that there are many different breeds that meet the
needs of many different societies and environments across the globe. Today, we’ve talked about
several examples of situations where a lack of diversity has or could cause problems. To wrap
this topic up in your mind today, I want to you to use a blank piece of paper for two things. First,
write a 5 sentence paragraph at the top that explains why biodiversity is important in agriculture.
Second, I want you to use your creative side and create your own breed of animal. For the lower
half of the paper, you’ll draw and label an agricultural animal that you have created in your brain,
telling us of its important characteristics and adaptive qualities. I’m not worried about the artistic
detail, but the descriptive detail. Use your imagination to complete this activity in the next 10
minutes. Go! (While students get started, write the instructions on the board for their reference,
then wander around the room to check progress. You may like to turn on music to aid in
creativity. After this activity, it’s fun to hang some of the papers around the room for display.)
Unit 7, Lesson 4: Evolution of Livestock Breeds
6
Review/Summary.
The activity in objective #3 reviews the concept of biodiversity well. To review the
vocabulary words and other concepts, orally ask questions off the short quiz that is to be
used for assessment.
Application
Extended classroom activity:
1.
Students could pick a breed association they are interested in and write for more
information. This helps them learn to write professional letters.
FFA activity:
1.
Students could contact a local breed association and partner with them financially or
in purpose on an FFA activity in order to create a stronger community.
SAE activity:
1.
If a student is raising livestock, they could become a member of the appropriate breed
association.
2.
Students could objectively look at the breed choice for their SAE and determine if it
best meets their needs or if adjustments could be made.
Evaluation.
Students should be evaluated on their writing skills for the completion of the biodiversity
paragraph as well as completing the notes and internet worksheet. In addition, a short quiz helps
them solidify the knowledge in their mind.
Answers to Assessment:
Livestock Breeds Evolution Quiz Answers
1.
2.
3.
4.
5.
6.
7.
8.
G.
H.
E.
F.
C.
A.
B.
D.
Unit 7, Lesson 4: Evolution of Livestock Breeds
7
Livestock Breeds Evolution
Powerpoint Presentation Notes
Name ___________________________________ Date _____________________
I.
What is a breed?
It is at least in part the perception of the _________________________ which decides when a
group of individuals constitutes a "breed".
Breeds are primarily distinguished by ______________characteristics: color, pattern, polled or
horned condition, or extreme differences in form and shape.
_____________________ breeds: new breeds being developed that combine the desirable
characteristics of several existing breeds.
______________: purity of ancestry; only animals in that particular breed have been mated to
produce the animal in question.
II.
Breed Development
B. The development or evolution of breeds can take different routes.
1. Change can occur as the result of selection for a small number of traits
Example:
2. Natural selection pressure based upon the environment in which they were
developed.
Example:
Unit 7, Lesson 4: Evolution of Livestock Breeds
8
Define these words:
Adaptation:
Niche:
Mutation:
Natural Selection:
Reproductive Isolation:
III.
Why is biodiversity important?
Example #1:
Example #2:
___________________ diversity should be maintained to help meet the potential challenge
resulting from changes in production resources and market requirements.
Unit 7, Lesson 4: Evolution of Livestock Breeds
9
Livestock Breeds Evolution
Internet Research Worksheet
Name ___________________________________ Date _____________________
Directions:
1.
Visit the following website: http://www.ansi.okstate.edu/breeds/
2.
Click on the species assigned to you by your instructor: cattle, goats, horses, sheep,
swine, or other (Top menu bar.)
3.
Click on a breed you have never heard of before and answer the questions on your
worksheet as they relate to that breed. (Left menu bar.)
4.
If you pick a breed that does not answer most of the questions, switch to a different
breed.
5.
Be prepared to tell the class about the information you find.
Species:_________________________
Breed Name:___________________________
Location of origin:
Approximate year:
Characteristics
1.
2.
3.
4.
5.
What product(s) does the animal produce:
What type of environment does it live in?
What is its reproductive history? (Has it been crossed with or improved by any other breeds?)
Describe one adaptive feature it has: (Example: horns on sheep that graze without protection.)
Unit 7, Lesson 4: Evolution of Livestock Breeds
10
Livestock Breeds Evolution
Quiz
Name ___________________________________ Date _____________________
Match the following phrases with the appropriate word found in the list below.
1.
_____Animals that, through selection and breeding, have come to resemble one another
and pass those traits uniformly to their offspring.
2.
_____New breeds being developed that combine the desirable characteristics of several
existing breeds.
3.
_____A mechanism that explains how populations evolve; organisms with favorable
variations survive.
4.
_____Evolution of structural, internal, or behavioral features that help an organism better
survive in an environment.
5.
_____The role of a particular species in a community regarding food, space, reproduction
6.
_____Random error or change in the DNA sequence that may effect whole chromosome
or one gene.
7.
_____Occurs when organisms that formerly interbred are prevented from producing
offspring.
8.
_____Should be maintained to help meet the potential challenge resulting from changes
in production resources and market requirements.
A.
B.
C.
D.
E.
F.
G.
H.
Mutation
Reproductive Isolation
Niche
Genetic Diversity
Natural Selection
Adaptation
Breed
Composite breeds
Unit 7, Lesson 4: Evolution of Livestock Breeds
11