Humans Influence Milk Production in Cattle

Question

Milk and other dairy products are an important source of nutrients such as calcium, magnesium, and vitamin D. Consumers in the United States purchase billions of pounds of milk each year. Between 1924 and the present, the dairy industry has undergone some changes. The graphs show the increase in milk production and the decrease in cattle populations.

The first line graph titled 'Milk Per Cow' shows Year on the horizontal axis from 1924 to 2015, in increments of 13. The vertical axis shows Pounds from 0 to 24000, in increments of 6000. At 1924, the line starts at a point slightly below 6000 and remains steady till 1950. Then, it shows a gradual rise till 2015 to a point slightly below 24000. The second line graph titled 'US Milk Cattle Inventory' shows Year on the horizontal axis from 1924 to 2015 in increments of 13. The vertical axis shows Number of Cows in millions from 0 to 30 in increments of 7.5. At 1924, the line starts at 22.5 and shows greater variations till 1950. After 1950, the line declines sharply before stabilizing between 1963 and 1976 at a point just above 7.5.

Dairy farmers across the country use different methods to increase their milk production. Two methods are shown.

The first farmer uses a selective breeding method. He selects only the cows with the highest milk yields and allows them to breed with his bull. The diagram shows his cattle population over many generations. Cows with high milk yields are outlined in red.

In the original population, 3 out of 12 cows produce the highest yields of milk. In the first generation, 5 out of 12 cows produce the highest yields of milk. In the second generation 7 out of 12 cows produce the highest yields of milk. In the third generation 9 out of 12 cows produce the highest yields of milk.

The second farmer uses a genetic modification method with the cattle on her dairy farm. Her cows have modified genes that have been introduced by humans. The modified genes enable the cows to produce more milk and produce offspring that have the modified gene. The diagram shows her cattle.

A modified gene is placed into the nucleus of a fertilized cow egg. The egg is implanted into the cow. The cow has five offspring that all have the same modified gene.

Constructed Response Question
In 2009, the domestic cow became the first livestock mammal to have its genome sequenced. A genome is the complete set of genes in the cell of an organism. The sequencing took six years to complete and involved the work of over three hundred scientists from around the world. Which method did the genome sequencing most benefit? Provide an explanation.

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Humans Influence Milk Production in Cattle
Milk and other dairy products are an important source of nutrients such as calcium, magnesium, and vitamin D. Consumers in the United States purchase billions of pounds of milk each year. Between 1924 and the present, the dairy industry has undergone some changes. The graphs show the increase in milk production and the decrease in cattle populations.

The first line graph titled 'Milk Per Cow' shows Year on the horizontal axis from 1924 to 2015, in increments of 13. The vertical axis shows Pounds from 0 to 24000, in increments of 6000. At 1924, the line starts at a point slightly below 6000 and remains steady till 1950. Then, it shows a gradual rise till 2015 to a point slightly below 24000. The second line graph titled 'US Milk Cattle Inventory' shows Year on the horizontal axis from 1924 to 2015 in increments of 13. The vertical axis shows Number of Cows in millions from 0 to 30 in increments of 7.5. At 1924, the line starts at 22.5 and shows greater variations till 1950. After 1950, the line declines sharply before stabilizing between 1963 and 1976 at a point just above 7.5.

Dairy farmers across the country use different methods to increase their milk production. Two methods are shown.

The first farmer uses a selective breeding method. He selects only the cows with the highest milk yields and allows them to breed with his bull. The diagram shows his cattle population over many generations. Cows with high milk yields are outlined in red.

In the original population, 3 out of 12 cows produce the highest yields of milk. In the first generation, 5 out of 12 cows produce the highest yields of milk. In the second generation 7 out of 12 cows produce the highest yields of milk. In the third generation 9 out of 12 cows produce the highest yields of milk.

The second farmer uses a genetic modification method with the cattle on her dairy farm. Her cows have modified genes that have been introduced by humans. The modified genes enable the cows to produce more milk and produce offspring that have the modified gene. The diagram shows her cattle.

A modified gene is placed into the nucleus of a fertilized cow egg. The egg is implanted into the cow. The cow has five offspring that all have the same modified gene.

Constructed Response Question
In 2009, the domestic cow became the first livestock mammal to have its genome sequenced. A genome is the complete set of genes in the cell of an organism. The sequencing took six years to complete and involved the work of over three hundred scientists from around the world. Which method did the genome sequencing most benefit? Provide an explanation.

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Answer 1

The genome sequencing of the domestic cow in 2009 most benefited the genetic modification method used by the second farmer.

Explanation: Genome sequencing provides detailed information about the genetic makeup of an organism. In the case of cattle, knowing the complete set of genes allows scientists and farmers to identify specific genes associated with high milk production and other desirable traits. This knowledge is essential for crafting targeted genetic modifications.

With the information gained from the genome sequencing, the second farmer can more effectively introduce modified genes that enhance milk yield. The identification and understanding of specific genes allow for precise interventions, leading to the development of genetically modified cows that not only produce more milk but also pass those modified traits onto their offspring.

In contrast, while the selective breeding method used by the first farmer can also benefit from genetic knowledge, it relies on a more gradual process of selecting and breeding individuals with desirable traits, rather than directly modifying their genetic material. The genome sequencing is more directly applicable to the process of genetic modification since it provides the foundational knowledge necessary to target specific genes for enhancement.