Resource: A Cow’s Digestive System
Media Type:
QuickTime Video
Length: 1m 35s
Size: 4.4 MB
Cows are ruminants, animals with a unique digestive system that allows them to live on otherwise unpalatable foods by repeatedly regurgitating and rechewing them as "cud." The cud is then swallowed again and further digested by specialized bacterial, protozoal and fungal microbes that live in the rumen, one of the four compartments of a cow's stomach. Learn more about a cow's digestive system in this video segment from Nature.
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Transcript (Rich Text Format Document)
Loading reviews...Teachers' Domain, A Cow’s Digestive System, published November 18, 2008, retrieved on ,
http://www.teachersdomain.org/resource/nat08.living.str.living.digest/
- Background Essay
- Questions for Discussion
- Standards
Print Background EssayCattle originally evolved over millions of years through a process of natural selection-also known as “survival of the fittest”-which made them adaptable to a wide variety of environments, including most of those inhabited by another highly adaptable species: humans. Once humans discovered how to domesticate cattle about 4,000 years ago, they began to selectively, or “artificially,” breed them for specific desired traits like meat and milk production. This resulted in animals fit less for survival in the wild than the satisfaction of human needs, but in purely genetic terms, the arrangement has proven highly successful for cattle. Cattle now thrive throughout the world in over 800 different breeds, each more or less successfully adapted to their environment and the needs of their human caretakers.
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Source: Nature: "Holy Cow"
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Major corporate support for the Nature collection was provided by Canon U.S.A. and SC Johnson. Additional support was provided by the Corporation for Public Broadcasting and the nation’s public television stations.