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Lesson 5.3 – Teacher Notes
In preparation for teaching this lesson, you should review the Concepts, Performance Objectives, Essential Questions, and Key Terms along with the PowerPoint® presentations prior to beginning the lesson with students. In addition, you should review all activities in order to familiarize yourself with the student directions, expectations, and the work students will complete.
PowerPoints®
This presentation addresses the categories of feedstuffs and the variability of nutritional value of feedstuffs. Roughages, concentrates, supplements, and feed additives are used to make complete rations for animals.
The presentation defines terms commonly used in feed analysis and on feed labels. Students will learn how to read a label and compare a feed label to a food label. This presentation assists students with Activity 5.3.3 It’s all on the label.
Activities, Projects, and Problems
Students will complete an inquiry lab in this activity to determine the energy content of different feedstuffs. Assign students to lab groups of four. When you demonstrate the activity, it is recommended that you have students practice with the LabQuest®.
Prior to the lab, collect 6–10 juice cans or tomato paste cans. The cans should be narrow (i.e., 1½ to 2 inches in diameter) and approximately 3 inches tall. Clean the cans out and drill two holes just under the rim. The holes should be large enough for a stirring rod to pass through.
Setting up the apparatus: Place the two rings on the ring stand. Place the utility clamp above the rings. Place the burner under the bottom ring stand and adjust so the iron wire will sit just above the flame. Hang the juice can in the top ring and adjust so it is approximately 2.5 cm above the food sample on the iron wire. Finally, place the temperature probe in the utility clamp and adjust so the probe is suspended in the water without touching any side of the can.
Hint: Feed samples require more heat than a match provides to begin combustion.
Due to the constraints of the lab setup, heat will be lost. Students will not collect the actual energy output of a feed, but as long as the conditions remain the same, comparable amounts of heat will be lost in each trial and results will be comparable.
Optional: Have students repeat the experiment using other feedstuffs or potential feedstuffs.
Follow specific Vernier LabQuest operation instructions as outlined on the activity sheet. For more assistance with LabQuest operation, refer to the LabQuest Reference Guide. For help using the gas pressure sensor refer to the Vernier Temperature Sensor Booklet.
Assess students using Activity 5.3.1 Answer Key.
Activity 5.3.2 What’s in it for me?
In this activity, students categorize common feedstuffs into nutrient groups and feed classifications. You will need a variety of feedstuffs for students to use. It is recommended that some samples be animal feed and some packaged for human consumption. By providing feeds used by both livestock and people, students will develop a better understanding of the nutrient categories.
You should provide at least sixteen samples from a variety of sources for your students to categorize (see Table 1). You can find many of the feedstuffs not used for humans at a feed store or dairy. Be sure to provide the nutritional labels with each feedstuff. If there is not a feedstuff label available, you may find the nutritional data on the NRC Feed Composition Tables at URL: http://books.nap.edu/catalog.php?record_id=1713. If you use the NRC Tables, make a note card similar to a feed label of the sample for students to reference.
Below is a list of suggested feedstuffs, but substitutions of locally available feeds is encouraged.
Table 1. Suggested Feedstuffs
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Alfalfa pellets |
Cottonseed meal |
Rolled oats |
Soybean meal |
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Barley |
Grass clippings |
Salt block |
Vegetable oil |
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Blood meal |
Grass hay |
Silage |
Vitamins |
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Corn |
Molasses |
Sorghum |
Wheat |
Students will need computer and Internet access to complete Part Three of the activity.
Assess students using Activity 5.3.2 Answer Key.
Activity 5.3.3 It’s all on the label
In this activity, students interpret the information on a feed label by defining terminology and comparing to a food label. Students also convert calories on a food package to the more common feed measure of Mcal/kg.
HOMEWORK: Assign students the task of finding a breakfast cereal label and converting the nutritional information on the label to units on a feed label. Most cereal companies have the nutritional information for their products located on the web.
Assess students using Activity 5.3.3 Answer Key.
Assessment
Lesson 5.3 Check for Understanding
Lesson 5.3 Check for Understanding is included for you to use as an assessment tool for this lesson. Lesson 5.3 Check for Understanding Answer Key is provided for grading purposes.