Nutrient Analysis (50 Pts) 1. List the components of Proximate Analysis (12 Pts) (Dry matter, crude protein, crude fiber, ether extract, ash, nitrogen free extract) 2. Name a procedure in proximate analysis that is not gravimetric. (4) (Crude protein is best answer. NFE also possible) 3. Why is the Kjeldahl nitrogen value multiplied by 6.25 to get crude protein? (6) (The average amino acid is 16% nitrogen, so to get from the measured nitrogen content back to the protein or amino acid level, you multiply by 6.25) 4. What has largely replaced the Kjeldahl procedure for determination of crude protein? (2) (Nitrogen analyzer) 5. Which of the following is not an essential nutrient? (2) a. Water b. Energy c. Carbohydrates d. Vitamins 6. Corn sample “A” was determined to have 7.5% Crude Protein while sample “B” was found to have 8.3% Crude Protein. Name 3 sources of variation in nutrient content of a feed ingredient? (6) (genetic variety of corn, location or environment it was grown in, temperature, rainfall, lab error, sampling error) 7. Why would the compound melamine have been added to a feed ingredient? (4) (Melamine is high in nitrogen, so adding a small amount to an ingredient gives a falsely high crude protein value. It is toxic to some species and caused a number of problems in the pet food industry.) 8. What are each of the following pieces of equipment used to determine that is related to nutrient analysis in feed ingredients? (2 each, 10 total) a. Bomb calorimeter - energy b. Gas chromatograph – fatty acids c. Inductively Coupled Plasma Spectrophotometry - minerals d. Nitrogen Analyzer – nitrogen content or crude protein e. Soxhlet extraction – lipid or fat content f. 9. What procedure has largely replaced the Crude Fiber determination in proximate analysis? (2) (the van Soest Procedure, or ADF and NDF) 10. Of all the nutrients that were discussed, which one is the value dependent on the species that is being fed the ingredient? (2) (Energy)Sample questions: 1. A feed ingredient was analyzed and found to contain 12% moisture, 12% crude protein, 2% ash, 3% ether extract and 4% fiber. Together, this only accounts for 33% of the mass of the ingredient. What accounts for the remainder? (Nitrogen free extract) 2. Name the classes of essential nutrients. (Water, Energy, vitamins, minerals, essential amino acids, essential fatty acids.) 3. Analytical procedures that are based on differences in weight are called _gravimetric__________________. 4. Which determination in the van Soest procedure is closest to the Crude fiber content of an ingredient? ADF is closest to Crude Fiber 5. How could you calculate the hemicellulose content of an ingredient? NDF – ADF =
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