The Ultimate Efficient Recycler
Students examine how cows help conserve natural resources by identifying the important role dairy cattle have in reducing, reusing, and recycling food processing by-products. Students identify each stage of the ecological cycle and the important role of decomposers.
- 5-10 brown paper bags
- 5-10 different feed stuffs
- Almond hulls, cottonseed, barley, culled carrots, etc. Many feed mills, dairies, universities or animal nutritionists will donate.
For each group:
- Set of four Ultimate Efficient Recycler journal entries
Essential File (map, chart, picture, or document)
by-product: an incidental or secondary product made in the manufacture of something else
compost: decayed organic material used as plant fertilizer
decomposer: an organism (soil bacterium, fungus, or invertebrate) that decomposes organic material
macroorganism: an organism large enough to be seen with the naked eye
microorganism: a microscopic organism such as bacterium, virus, or fungus
Background Agricultural Connections
This lesson is part of a series called, Milk Matters: Discovering Dairy. These lessons introduce students to the history, production, nutritional value and economic significance of the dairy industry. Other related lessons include:
- Cowabunga! All About Breeds
- Sun, to Moo, to You!
- Milk Makin' Math
- The Ultimate Efficient Recycler
- A Day Without Dairy
Dairy cows are truly efficient recyclers. Because of their complex multi-compartment stomachs, they can consume feedstuffs that would be difficult or impossible for humans to digest, and then convert the feed into dairy products that humans can consume. The ingredients used for cattle feed include food processing by-products that would otherwise be sent to landfills. More than 25 percent of food processing by-products are fed to cattle. These feed products may include sugar beet pulp, almond hulls, canola seed pulp, citrus pulp, potato peels, culled vegetables, bakery waste, corn stalks, tomato pulp, grape skins, cottonseed, soy hulls and more. Eighty-five percent of what cattle eat is material that people cannot digest.
Not only do dairy cows recycle our unwanted leftovers to produce delicious dairy products, they also produce waste that we re-use for a variety of purposes. One way we “re-use” is applying properly composed manure from dairy cows to crops for fertilizer.
Macroorganisms and microorganisms play a vital role in turning cattle waste into a useful resource for humans. Worms, grubs and microbes are all examples of organisms that chew and break down material such as twigs, roots, manure and leaves.
Earthworms are macroorganisms that eat their way through their surroundings, consuming anything that is soft enough for them to chew. All “food” that is consumed is ground up in the gizzard, leaving the worm’s body in the form of dark, nutrient-rich castings. These castings are an important contribution to soil fertility. When macroorganisms die and decay, their bodies also add nitrogen and other elements to the compost.
Microorganisms, like bacteria, begin the breakdown of material, making it easier for worms and other macroorganisms to do their job. Many different types of microorganisms are at work in composted manure. Given the right environmental conditions--such as proper moisture, temperature, air, a favorable balance of carbon and nitrogen and lots of surface area to work on--bacteria will thrive. Since bacteria are smaller and less mobile than other organisms, they are less able to escape an environment that becomes unfavorable. A decrease in the temperature of the compost pile or a drastic change in pH can kill these decomposers. Once undergoing the process of decomposition, dairy farmers are able to use properly composted manure to enrich the soil, aiding in healthy plant growth.
Dairy farmers add composted manure to crops, which acts like a “homemade” fertilizer. Plants grow healthy and strong with the added nutrients. Dairy farmers use these crops to produce more feed ingredients, such as corn stalks, and the cycle begins again from the beginning.
More background information on the dairy industry can be found here.
Interest Approach - Engagement
- In this lesson, students will examine dairy cattle’s role in conserving natural resources. To introduce the topic ask students what it means to recycle. Help guide your students to the correct answer. Ask students if they think that a dairy cow could recycle. Give a few examples of how a dairy cow can use items that we would consider as waste.
- Cottonseed: Most of your students are wearing clothes made out of cotton. Inside of a cotton boll (flower) are seeds that are extracted because they are not needed to make cotton fabric. These seeds are used to feed dairy cows, who then produce milk and milk products that are a healthy addition to our diets.
- Sugar Beet Pulp: Some of the sugar we use in cooking is produced by a sugar beet. Once the sugar is extracted from the beet the pulp remains. Sugar beet pulp is a valuable feed for cattle that is high in energy. It takes a lot of energy for a cow to produce milk. They can obtain some of this energy from beet pulp, a by-product that cannot be digested well or provide nutrition to us as humans.
- Almond Hulls: Almonds grow on trees. The nut is encased in both a shell and a fibrous cover called a "hull." Cattle have four chambers in their stomach which allow them to digest and gain nutrients from items that humans cannot. Dairy cows can eat almond hulls as part of their specially formulated diet. Cows use this energy to produce milk.
- There are many more examples of how dairy cattle help recycle and preserve valuable resources.
- Place several types of food processing by-products used for dairy feed in separate, brown paper bags. Students take turns feeling inside the bags and guessing the feed ingredient. Review with students, identifying the original product and the changes that happened to create each by-product foodstuff.
- Explain to students that dairy cows help us recycle materials that would normally be considered waste. We call these materials “byproducts.” For example, after farmers harvest ears of corn, the stalks remain. These stalks are a nutritious addition to animal feed. Re-using products is an important way for humans to reduce the amount of waste sent to landfills. By recycling the material and using it as nutritious ingredients for dairy feed, we reduce our impact on the environment. Work with students to identify other waste products that are used in the dairy industry as feed.
- Being a resourceful consumer of by-products is not the only way dairy cows are ultimate, efficient recyclers. In a moment, students will break into groups and discover the other ways dairy cows reduce, reuse and recycle.
- Break students into cooperative learning groups of four. Read the following script to students: (The following journal entry was written by 5th grader Lily Longacre.) Give each learning group a packet of Ultimate Efficient Recycler journal entries. Each student reads one of the journal entries and responds to the reading comprehension questions at the bottom of the page.
- After several minutes, students gather in their assigned cooperative learning groups. Each student summarizes what they read to the group and shares the answers to their questions. Review each of the questions as a class.
- Instruct students to place their journal entries in the correct chronological order, identifying areas where they see the process of recycling, reducing and reusing. Students should be able to review the process from beginning to end and recognize that these steps are repeated to form an effective cycle.
- Cows consume feed, made of food processing by-products.
- The dairy farmer creates compost and collects manure.
- Manure is used to fertilize the field.
- The dairy farmer harvests the field and feeds the by-products to the dairy cattle.
- Some possible discussions about this lesson may include:
- What type of diagram is appropriate to illustrate this process?
- Is it a timeline or is it cyclical? Why?
- What are some lessons we have learned from dairy cows that will help us reduce, reuse and recycle in our own lives?
- How are these interactions an example of a viable ecosystem?
- How would life be different without decomposers?
Concept Elaboration and Evaluation
After conducting these activities, review and summarize the following key concepts:
- Natural resources such as soil, water, air, plants and minerals are required to produce milk.
- Farmers take stewardship of the land and the natural resources they need to produce milk.
- Farmers recycle and reuse many resources and turn them into useable resources.
- Place examples of feed items in film canisters. Given an example of each feedstuff, students identify which ingredient is in each canister, based on the sounds they make.
- Given paper and markers, students work in their groups to create a “cycle” that represents what is happening in the four journal entries
As a class, create your own compost pile. Visit The California School Garden Network for classroom activities and step-by-step directions. Observe and monitor changes in pH, insect activity, heat and size. Students hypothesize future changes in the compost. Students can also create personal compost piles in plastic water bottles or milk cartons and monitor changes on a smaller scale.
Students research the potential of “catching” methane gas from manure and using it as an energy source. Go on a field trip to a dairy with a methane digester.
Create a storybook about the efficient and resourceful dairy cycle. Students also create a storybook sharing how they reduce, reuse and recycle.
Students write their own journal entry, written from the perspective of a dairy cow.
This lesson was funded in 2008 by the California Milk Advisory Board and the California Farm Bureau Federation. To meet the needs of California educators, Milk Matters: Discovering Dairy was created to meet the Curriculum Content Standards for California Public Schools. The unit also includes a collection of relevant resources about the dairy industry.
Executive Director: Judy Culbertson
Layout and Design: Imelda Muziom