Old McDonald Wouldn’t Recognize This Cow. It’s Been Bred To Be A “Super Cow”

Question

Meet the Belgian Blue, the cattle version of Arnold Schwarzenegger! Contrary to what you may think, these bovine bodybuilders aren’t the result of intensive steroid use. Similarly, to the featherless chicken, this man-made monstrosity is a prime example of the genetic power that selective breeding holds.

History & Origins

As suggested by its name, the breed originates from central and upper Belgium. Its history tracks back in the nineteenth century, from crossing local breeds with a Shorthorn breed from the U.K. Possibly, the Charolais cattle (a heavy breed from France) was cross-bred as well.

The modern version of the breed was developed in the 1950's by Professor Hanset, who worked at an artificial insemination center in Liege province. The gene mutation responsible for the breed’s heavily muscled stature (more on this later) was maintained through line-breeding, to the point where the condition became a fixed property of the Belgian Blue breed.

The breed was introduced in the United States in 1978, by Nick Tutt, a farmer from central Canada who immigrated to west Texas and exhibited the Belgian Blue to the local universities and breeders.

Why is the Belgian Blue so Muscular?

The Belgian Blue's sculpted, heavily muscled, bodybuilder-like appearance is known as "double-muscling." The condition is heritable and results from an increased number of muscle fibers (hyperplasia) rather than the normal enlargement of individual muscle cells (hypertrophy).

The increased muscle tissue is due to a natural mutation in a gene which is involved in muscular hypertoryphy. This gene is responsible for the expression of a protein called myostatin ("myo" meaning muscle and "statin" meaning stop). You probably guessed it right, myostatin inhibits muscle growth. Essentially, the breed produces less myostatin and thus produces more muscle tissue than the average cattle. Furthermore, the same mutation apparently interferes with fat deposition, resulting in very lean meat.

Physical Characteristics

The Belgian Blue is a large sized cattle breed, with rounded outline and prominent muscles on the shoulders, back, loin and rump. The back is straight, rump is sloping, tail set is prominent and the skin is fine. The legs are thin but strong. Individuals vary in color, which may be while, blue roan or sometimes even black.

Meat Quality and Nutritional Value

Several studies have shown that the meat and milk produced by Belgian blues can be consumed with no risk by humans.

In an extensive 3 year examination, done by the USDA at the Meat Animal Research Center, Clay Center, Nebraska, it was observed that Belgian blue meat contains less fat and more protein.

Multiple Select Question
Using the information from the passage and your knowledge of science, select all of the following scenarios that demonstrate how humans have influenced the inheritance of desired traits in organisms.
A.
Deer mice migrated from forests to sandhills. Future generations eventually had more light brown fur than dark brown.
B.
Stalks of corn naturally have differing amounts of ears of corn on each stalk. Farmers chose stalks of corn that produced the most ears of corn per stalk to breed together, making future generations more productive.
C.
Scientists have taken the gene that programs poison in scorpion tails and looked for ways to combine it with cabbage to prevent caterpillars from eating them. They edited the gene so that it is not harmful to humans.
D.
Scientists suspect that the shape of human hands have changed over time. Those with better manual dexterity had an advantage in tossing a spear, making tools or throwing a rock in order to get the food they needed to survive.
E.
Scientists studying human-genetic disorders have injected pig embryos with jellyfish DNA. When the piglets are put under a black light, they emanate an eerie green glow.

Answer 1

Based on the provided passage about the Belgian Blue cattle and the concept of how humans have influenced the inheritance of desired traits in organisms, the scenarios that demonstrate this influence include:

B. Stalks of corn naturally have differing amounts of ears of corn on each stalk. Farmers chose stalks of corn that produced the most ears of corn per stalk to breed together, making future generations more productive.

• This scenario illustrates selective breeding, where farmers intentionally select plants with desired traits (more ears of corn) to pass on those traits to future generations.

C. Scientists have taken the gene that programs poison in scorpion tails and looked for ways to combine it with cabbage to prevent caterpillars from eating them. They edited the gene so that it is not harmful to humans.

• This scenario involves genetic engineering, where scientists are intentionally manipulating genes to create desired traits in organisms (in this case, a cabbage that is resistant to caterpillars).

The other options A, D, and E do not clearly fit the scenario of human influence on inheritance in the context of breeding or genetic manipulation for specific desired traits:

A. Deer mice migrating and developing lighter fur is an example of natural selection, not human influence.
D. Changes in human hand shape over time due to manual dexterity relate more to natural selection rather than direct human influence on inheritance.
E. Injecting pig embryos with jellyfish DNA can be seen as an example of genetic manipulation, but it doesn’t relate directly to selected breeding for desired traits in the way the Belgian Blue has been bred.

Thus, the correct answers are B and C.