Dry Matter vs. As-Fed Basis

1. Dry Matter vs. As-Fed Basis

2. Dry Matter vs. As-Fed • Important concept in feed analysis • Expression of nutrient content or feed amount on a "dry matter" or "as-fed" basis

3. Dry Matter vs. As-Fed • All feeds contain water, some more than others • Consider: • Alfalfa pasture = 80.2% water • Alfalfa hay = 9.5% water

4. Dry Matter vs. As-Fed • When comparing the nutritional value of feeds, • It must be done on a dry matter basis to be valid

5. Dry Matter vs. As-Fed • As-Fed – as normally fed to animals • Contains water • Dry matter – does not contain water

6. Dry Matter vs. As-Fed • DM content of a feed is the most important component because it contains almost all of the nutrients • DM in a feed is: • % dry matter = 100 – % water

7. Dry Matter vs. As-Fed • Alfalfa pasture = 80.2% water • DM = 100 – 80.2% = 19.8% • Alfalfa hay = 9.5% water • DM = 100 – 9.5% = 90.5%

8. Dry Matter vs. As-Fed • Compare protein content of the alfalfa pasture and alfalfa hay • On an as-fed basis, alfalfa hay appears to contain more protein • 19.0% vs. 4.1%

9. Dry Matter vs. As-Fed • On a dry matter basis, however, the hay and pasture are very similar • 21.0% vs. 20.7% • The as-fed protein comparison is misleading

10. Concentration (%, Mcal/kg) Start with As-Fed Basis of Nutrients (The “pie” represents nutrients in a feed)

11. Concentration (%, Mcal/kg) Convert to DM by removing water

12. Concentration (%, Mcal/kg) Notice how nutrient %’s go up (The “pie” represents nutrients in a feed)

13. For A Nutrient Concentration • As-Fed to DM • Nutrient % gets BIGGER • (Because water is removed) • DM to as-fed • Nutrient % gets smaller • (Because water is added back in)

14. Feed Amount (g, lb, etc.) As-Fed Basis Weight = 5 lb (Contains water)

15. Feed Amount (g, lb, etc.) Dry Matter Basis Weight = < 5 lb (Water removed)

16. For A Feed Amount • As-Fed to DM • Feed amount gets smaller • (Because water is removed) • DM to as-fed • Feed amount gets BIGGER • (Because water is added back in)