the perfect cow
Using your knowledge of selective breeding, complete the Perfect Cow activity.
INTRODUCTION
Cattle evolved through the slow process of natural selection until human domestication, which rapidly accelerated their development as an artificially selected species fit less for survival than to satisfy human needs. This lesson focuses on how and why humans have been so successful in selectively breeding cattle to suit these needs, while also exploring the limitations and consequences of this success.
Natural selection describes the process by which organisms best adapted to their environments are the ones that survive and reproduce.
TASK 1
Imagine they are a tribe of prehistoric hunter/gatherer nomads living in a savannah (a rolling grassland scattered with shrubs and isolated trees). You have several species of animal in your environment which you can attempt to domesticate as a food source to relieve the pressures of the hunt. Download and use the “Man’s Best Friend Student Organizer”. For each question category on the student organizer, determine why you think the question is important and relevant. Explain your answers in as much detail as possible.
Based on your student organizer answers and the class’s discussion vote on which animal you think offers the most to your hypothetical grassland tribe? Remember many of your prehistoric ancestors came to the same decision, and that wherever cattle existed throughout the world, they came to be domesticated to provide meat, milk, and other resources.
In your exercise book write down what else cattle have provided for humans?
TASK 2
You will now be watching a clip describing some specific traits humans have artificially selected in cows to give them certain desirable attributes. In your exercise book write down the traits that humans seek in breeding a good beef cow.
“Desirable Breeding Traits in Cattle.” (Access the video segments for this lesson at the Video Segments
Page,http://www.pbs.org/wnet/nature/lessons/the-perfect-cow/video-segments-holy-cow/1536/
PAUSE the clip after the words “…they’ve been selected by the butcher, in essence.”
In your exercise book write down a response to the focus question. (Meat cattle are bred to have short legs and a stocky build with large quantities of meat.)
Write down the traits that humans seek in a good dairy cow.
PLAY the clip through to the end. Respond to the focus question. (Dairy cows are bred to have good udders, well-placed teats, well-setlegs, open ribs-all attributes that help it produce more milk.)
TASK 3
You will now be taking a closer look at one particular breed similar to those they have just seen in the video clip. Go
to the “Breeds of Livestock” Web site and use the menu at the left of the screen to select the Shorthorn. Read the first two paragraphs. Respond to the focus question. (It originated in England, and is valued because it puts ona lot of meat and produces a lot of milk.)
For centuries the Shorthorn has been artificially selected for these traits. Would you consider these the most important traits in any cow? Write down an Explaination in your exercise book
TASK 4
You will now be watching another video clip featuring cattle that have evolved through a combination of artificial and natural selection to fit some other criteria. PLAY Clip 3, “Different Breeds of Cattle.” (Access the video segments for this lesson at the Video Segments Page, http://www.pbs.org/wnet/nature/lessons/the-perfect-cow/video-segments-holy-cow/1536/.
In your exercise book writ down what other characteristics besides meat and milk volume might be desirable to breed into cattle?
TASK 5
On a world climate map, have locate England. Describe the climate in England.
Find India on the world climate map. In your exercise book write down What do they think the climate is like there? Do
they think cattle in India are any different from the Shorthorn?
Return to the “Breeds of Livestock” Web site and use the menu at the left of the screen to select the Brahman.
Read the two introductory paragraphs and the “Physical Characteristics” section of the Web page. Write down the traits of the Brahman that have enabled it to survive and thrive in India’s hot climate.
While all cows evolved the ability to survive on grass, over time different breeds have evolved additional adaptive attributes that have helped them to survive and thrive in their particular climates and environments.In your exercise book write down if you think that Shorthorn cattle would thrive in India? Explain your answer.
Do you think that the Brahman’s heat-adaptive traits have come at the expense of any other
attributes?
What does a cow’s growth mean for the human who raises it?
Do you think that less meat per cow is necessarily a problem for Indian cattle raisers? Explain
Many hot weather countries such as Brazil produce and eat beef. Find Brazil on the climate map.
What is the climate like there?
What would you do if they were tropical cattle ranchers like the Brazilians who want more meat on their cows?
TASK 6
Go to the “Genetic Engineering” Web site. Read the “Selective Breeding” section. In your exercise book, Define “hybridization.”
There are approximately 1.3 billion cattle in the world today approximately twice the number that existed 40 years ago. Can you think of any another species that has doubled its population over the same period?
In your exercise book define the link?
The 1.3 billion cattle are increasingly dominated by arelatively few breeds and hybrids that have been selected by humans for their superbmeat and milk production traits. Can selectively breeding hybridcattle can produce “a perfect
cow.” Explain
TASK 7
By artificially selecting certain qualities and attributes useful to humans, we also risk losing naturally selected attributes necessary for a species’ health and survival. You will be looking at a real-world case study involving artificial and natural selection. Read the article “A Dying Breed” which discusses the increasing hybridization by Bahiman cattle ranchers in Uganda of their native Ankole cattle with Holstein cattle from the United States.
Consider the strengths and weaknesses of each breed, and the various needs of the Bahiman population.
Take notes with the “Traits of Ankole and Holstein Cattle Student Organizer.”
In your groups complete the "Finding the Balance"Student Organizer.
INTRODUCTION
Cattle evolved through the slow process of natural selection until human domestication, which rapidly accelerated their development as an artificially selected species fit less for survival than to satisfy human needs. This lesson focuses on how and why humans have been so successful in selectively breeding cattle to suit these needs, while also exploring the limitations and consequences of this success.
Natural selection describes the process by which organisms best adapted to their environments are the ones that survive and reproduce.
TASK 1
Imagine they are a tribe of prehistoric hunter/gatherer nomads living in a savannah (a rolling grassland scattered with shrubs and isolated trees). You have several species of animal in your environment which you can attempt to domesticate as a food source to relieve the pressures of the hunt. Download and use the “Man’s Best Friend Student Organizer”. For each question category on the student organizer, determine why you think the question is important and relevant. Explain your answers in as much detail as possible.
Based on your student organizer answers and the class’s discussion vote on which animal you think offers the most to your hypothetical grassland tribe? Remember many of your prehistoric ancestors came to the same decision, and that wherever cattle existed throughout the world, they came to be domesticated to provide meat, milk, and other resources.
In your exercise book write down what else cattle have provided for humans?
TASK 2
You will now be watching a clip describing some specific traits humans have artificially selected in cows to give them certain desirable attributes. In your exercise book write down the traits that humans seek in breeding a good beef cow.
“Desirable Breeding Traits in Cattle.” (Access the video segments for this lesson at the Video Segments
Page,http://www.pbs.org/wnet/nature/lessons/the-perfect-cow/video-segments-holy-cow/1536/
PAUSE the clip after the words “…they’ve been selected by the butcher, in essence.”
In your exercise book write down a response to the focus question. (Meat cattle are bred to have short legs and a stocky build with large quantities of meat.)
Write down the traits that humans seek in a good dairy cow.
PLAY the clip through to the end. Respond to the focus question. (Dairy cows are bred to have good udders, well-placed teats, well-setlegs, open ribs-all attributes that help it produce more milk.)
TASK 3
You will now be taking a closer look at one particular breed similar to those they have just seen in the video clip. Go
to the “Breeds of Livestock” Web site and use the menu at the left of the screen to select the Shorthorn. Read the first two paragraphs. Respond to the focus question. (It originated in England, and is valued because it puts ona lot of meat and produces a lot of milk.)
For centuries the Shorthorn has been artificially selected for these traits. Would you consider these the most important traits in any cow? Write down an Explaination in your exercise book
TASK 4
You will now be watching another video clip featuring cattle that have evolved through a combination of artificial and natural selection to fit some other criteria. PLAY Clip 3, “Different Breeds of Cattle.” (Access the video segments for this lesson at the Video Segments Page, http://www.pbs.org/wnet/nature/lessons/the-perfect-cow/video-segments-holy-cow/1536/.
In your exercise book writ down what other characteristics besides meat and milk volume might be desirable to breed into cattle?
TASK 5
On a world climate map, have locate England. Describe the climate in England.
Find India on the world climate map. In your exercise book write down What do they think the climate is like there? Do
they think cattle in India are any different from the Shorthorn?
Return to the “Breeds of Livestock” Web site and use the menu at the left of the screen to select the Brahman.
Read the two introductory paragraphs and the “Physical Characteristics” section of the Web page. Write down the traits of the Brahman that have enabled it to survive and thrive in India’s hot climate.
While all cows evolved the ability to survive on grass, over time different breeds have evolved additional adaptive attributes that have helped them to survive and thrive in their particular climates and environments.In your exercise book write down if you think that Shorthorn cattle would thrive in India? Explain your answer.
Do you think that the Brahman’s heat-adaptive traits have come at the expense of any other
attributes?
What does a cow’s growth mean for the human who raises it?
Do you think that less meat per cow is necessarily a problem for Indian cattle raisers? Explain
Many hot weather countries such as Brazil produce and eat beef. Find Brazil on the climate map.
What is the climate like there?
What would you do if they were tropical cattle ranchers like the Brazilians who want more meat on their cows?
TASK 6
Go to the “Genetic Engineering” Web site. Read the “Selective Breeding” section. In your exercise book, Define “hybridization.”
There are approximately 1.3 billion cattle in the world today approximately twice the number that existed 40 years ago. Can you think of any another species that has doubled its population over the same period?
In your exercise book define the link?
The 1.3 billion cattle are increasingly dominated by arelatively few breeds and hybrids that have been selected by humans for their superbmeat and milk production traits. Can selectively breeding hybridcattle can produce “a perfect
cow.” Explain
TASK 7
By artificially selecting certain qualities and attributes useful to humans, we also risk losing naturally selected attributes necessary for a species’ health and survival. You will be looking at a real-world case study involving artificial and natural selection. Read the article “A Dying Breed” which discusses the increasing hybridization by Bahiman cattle ranchers in Uganda of their native Ankole cattle with Holstein cattle from the United States.
Consider the strengths and weaknesses of each breed, and the various needs of the Bahiman population.
Take notes with the “Traits of Ankole and Holstein Cattle Student Organizer.”
In your groups complete the "Finding the Balance"Student Organizer.
