Target Grade Level / Age Range:


Estimated Time:

45 - 90 min (depending on availability of guest speaker)


Students will understand the role of enzymes in the diet, particularly the diet of pigs. Students will practice percent-by-mass calculations using parts of animal feed mix. Check for prior knowledge; balancing rations for protein, energy, etc.; also review weights and measures.


  • Enough ingredients for each student/group to make 20 grams of “pig feed”. Possibilities for corn and soybean meal include cereals (Cheerios, Chex, Crispix, etc), dried fruits (raisins, craisins) and baking chips (chocolate chips, white chocolate chips, butterscotch chips, etc) can be used for the terminal base, enzyme and amino acids.
  • Resealable bag for each student/group
  • Balances with weighing boats
  • Calculators
  • Blender: use for showing different consistencies of feed additives when mixing

Essential Files


  • Catalyst - a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
  • Enzyme - a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction.
  • Percent-by-mass – one way of showing the concentration of a mixture or the relative make-up of a compound

Background – Agricultural Connections

Catalysts are necessary in many chemical reactions to reduce the activation energy for the reaction and thereby make the chemical reaction occur. Enzymes are examples of catalysts in the digestion process.

Enzymes are proteins or protein-based molecules that increase nutrient utilization in feed. They have two key roles—they break down a larger molecule into one or more smaller molecules or they combine smaller molecules into a large molecule. Either way, enzymes help convert a less digestible component of feed (e.g. fiber) into a more usable form for the animals to utilize for growth, egg production, etc.

Enzyme supplementation in animal feed shows numerous benefits. One major plus includes improved gut health by making nutrients more available to the animal and less available as a nutrient source for “bad” bacteria. By making nutrients more available, enzymes are able to reduce feed costs, improve feed conversion, and improve the consistency in the diet. Finally, since nutrients are more available for the animal to use, less quantities of nutrients are excreted in waste. This makes livestock production more beneficial to the environment through enzyme supplemented diets.  

Interest Approach

Review the major components of swine feed (corn, soybean meal, terminal base additive, enzyme additives, and amino acids). Review the purpose of each of these ingredients. Review what a catalyst is and how enzymes serve as catalysts in the digestive process.  Pass out the Make Pig Feed worksheet

Students will mix their own “pig” feed using a variety of cereals and snack foods as representatives of the parts of a pig’s diet. Students will not be given information on what a pig needs in its diet prior to this activity but will be asked to guess what to include based on their own knowledge of a healthy diet. Instruct students that they must weight out 20 grams of feed including:

  • Chex or Crispix cereal representing corn
  • Roasted soybeans to represent soybean meal
  • Dried fruits (raisins, craisins) representing terminal base
  • Chocolate chips representing enzymes
  • White chocolate chips representing amino acids.

Review how percent-by-mass is calculated for a mixture. Instruct the students that they will be creating 20 grams of pig feed - representing a 2,000 lb. mix. Pigs will typically then be fed approximately 3% of their body weight per day. The ingredients are mixed in bulk to save time and money. Students should complete the hypothetical column of the worksheet calculating their amounts and weighing and measuring each ingredient. The total weight should not be more than 20 grams. 


  1. Display the Swine Feed Ingredient Label. Or distribute one copy to every student. 
  2. Using this ingredient label, fill out the worksheet starting with the Mass Needed to Make 1 Ton column. Use the figures for a 240 lb. pig. Then have students calculate the percent by mass and complete that column. Finally, using those percentages, based on 20 grams, what should their feed ration actually have looked like? Complete the Actual column.
  3. Allow students to eat their “pig feed” if weighing boats, balances, and other materials used were clean.
  4. Distribute one copy of the Ration Analysis plan to each student. Students can work in pairs or as individuals to research each question and formulate an answer. Students can use websites or other classroom resources as available to conduct research. Allow for 10-20 minutes of work time. Assist students as needed. When most students have finished, bring the class back together and review their answers. Use the provided key to ensure the students have found the correct answers. 
  5. If possible, arrange for a guest speaker or FarmChat® with an animal nutritionist, hog farmer, or other individual familiar with the nutrition needs of pigs. If no guest speaker is available, discuss the make-up of the swine feed, importance of enzymes, amino acids and minerals. Compare the makeup of swine feed to that of beef, poultry or other species raised in your given area.
  6. As homework, or in class as time allows, have students answer the two questions on the bottom of the ingredient label handout. This might require additional independent or guided student research.

Did you know? (Ag facts)

  • Iowa has more than 6,000 hog farms.
  • 94 percent of Iowa’s hog farms are family owned enterprises.
  • As of 2015, 141,813 jobs were associated with the Iowa pork industry.
  • One in nearly 12 working Iowans has a job tied to the pork industry.
  • Of the Iowa hog farms, 39 percent (2,451 farms) have 1,000 pigs or less.
  • At any one time, there are approximately 22 million pigs being raised in Iowa.
  • Iowa producers market approximately 48 million hogs a year.
  • Nearly one-third of the nation’s hogs are raised in Iowa.
  • Iowa is the number one pork producing state in the U.S. and the top state for pork exports.
  • Exports of pork from Iowa totaled more than $2.1 billion in 2018.
  • Japan, Hong Kong, Canada, Mexico and South Korea are the leading customers for Iowa pork.

Extension Activities (how students can carry this beyond the classroom)

  • Research other livestock that might require or benefit from enzyme supplements in their diet.

Suggested Companion Resources (books and websites)



Kim Poeckes

Organization Affiliation

South O’Brien High School

Agriculture Literacy Outcomes

  • T1.9-12.h

Iowa Core Standards

  • HS-ETS1-3
  • HS-PS1-4
  • AS.03
  • AS.03.02

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