The availability of nutrients is important to maintaining the diets of livestock to keep them healthy. Having the correct ratio of nutrients is important to ensure that feed nutrients are not wasted, not overfed, and that feed efficiency is optimized on the farm. Scientists use specialized testing protocols to determine the major components required for healthy growth and the development of livestock.
Fermentation is the process in which sugars are broken down and fed to yeast to produce ethanol and carbon dioxide. All the remaining nutrients: protein, fat, minerals, and vitamins, are concentrated into distillers grains, which is a valuable feed for livestock.
Our job today is to test where the most nutrient availability is located by comparing corn slurry (before fermentation) with fermented corn mash. In this lab we will be focusing on three of these major nutrients, glucose, starch, and protein, which are vital components for healthy livestock.
Note: The following procedures are what you will use if you are doing this as a stand-alone lab. You will need to make up the mash and slurry prior to starting the lab. You also have the option to perform this lab as part of the sequence in ethanol distillation. Kansas Corn: Ethanol – Corn Mash and Distillation is the recommended unit to perform first in the sequence. The Nutrient Test can be done before and after fermentation, as well as after distillation is complete, to compare the levels of nutrients in the different stages of production.
In the United States, commercial production of fuel ethanol involves breaking down the starch present in corn into simple sugars, also called “glucose”. These sugars are then fed to yeast, which begins the process of fermentation. The main product is used as ethanol – it is primarily found as a fuel additive in the gasoline used in our vehicles. Some of the other products include animal feed, corn oil, and carbon dioxide. The remaining nutrients include proteins, fats, minerals, and vitamins that are essential in use in feed for livestock. Our focus is on the nutrient availability of the products before fermentation occurs and after. We will be using three indicators to test for nutrient availability – Benedict’s Solution, Lugol’s Solution, and Biuret Solution. Benedict’s Solution will detect the presence of glucose, and it will provide an orange to red precipitate (form a solid) after heating. The Lugol’s Solution (Iodine) will turn black when starch is present. The Biuret Solution will turn purple when protein is present. This process will allow us to see where the nutrients are available at different times of the production of corn products, like ethanol.
Let students discuss their ideas, and guide the discussion without telling them if they are right or wrong.
Which of these, corn slurry (before fermentation) or corn mash (after fermentation), will provide the highest nutritional value to livestock after fermentation has occurred? Why?
Protein Indicator Test (Do not heat; heating will cause the proteins to breakdown which will give a negative test.)
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Have the students answer the following questions:
The students will complete the DDG Nutrient Testing Student Packet as an assessment for the lab. After collecting the data with their group, each student is responsible for completing the Reflection and Conclusion section on their own. The students will then complete the lab report on their own, with the data from their lab packet.
Protein is vital for the health and upkeep of livestock. Farmers not only need to make sure their livestock is healthy, they also have to do this as economical as possible. If you had a feedlot with 1,000 head of cattle, which type of feed would you choose for your cattle? Do some research to compare the different benefits between using distillers grains (WDG) (DDG) to other corn-based feeds in the daily diet of livestock. Look for the topics below during your research. Write a two-paragraph summary of your findings.
Any educator electing to perform demonstrations is expected to follow NSTA Minimum Safety Practices and Regulations for Demonstrations, Experiments, and Workshops, which are available at http://static.nsta.org/pdfs/MinimumSafetyPracticesAndRegulations.pdf, as well as all school policies and rules and all state and federal laws, regulations, codes and professional standards. Educators are responsible for abiding appropriate legal standards and better professional practices under a duty of care to make laboratories and demonstrations in and out of the classroom as safe as possible. If in doubt, do not perform the demonstrations.
Investing in teachers is a priority therefore the Kansas Corn Commission is committed to providing free materials and training to help teachers excel in the classroom. Distillation kits and funding for ethanol plant tours are available to teachers who teach Kansas Corn’s ethanol labs. Teachers who seek to expand their knowledge and skill of these labs are encouraged to seek out a training opportunity.