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Ingredients and complete feeds should be analyzed on a regular basis to monitor quality, to help avoid errors in estimating nutrient content, and to identify inaccuracies in feed formulation or feed manufacturing.
The analyzed values generally do not match the expected values perfectly because of normal variations that occur during sampling and laboratory analyses. The analytical variance is usually considered when determining the acceptability of feeds and ingredients. This variation is generally around 15% to 25% for most nutrients.
The analytical variance and concentration ranges in the table are based on historic check sample data from AAFCO (American Association of Feed Control Officials). The values given in the table refer to a true analytical variation and not a tolerance value that may be specified by a regulatory agency.
The analytical variation values apply both above and below the guarantee and are equally correct. For example, for crude protein the analytical variation is calculated as:
%AV = (20 ÷ x) + 2
where:
• %AV = percent analytical variation
• x = percent guaranteed protein
If the crude protein guarantee was 10%, then
%AV = (20 ÷ 10) + 2
= 2 + 2
= 4
This means the allowed analytical variation is 4% of the 10% guarantee or ±0.4% crude protein. Thus, the reported analytical result could range from 9.6% to 10.4% and be within the range of acceptable analytical variation.
NOTE: The analytical variations and laboratory results used in calculations should be interpreted on an “as-fed”, “as-is”, or an “as-received” basis, but not be calculated on a dry-matter basis.
¶ Table 1. Analytical Variance for Analysis of Feed Ingredients and Feeds (On “As-Fed” Basis) |
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| Analysis | Analytical variance, %1,2 | Concentration range2 | Determination method | ||
| Proximate analysis | |||||
| Ash | (45 ÷ x) +3 | 2 to 88% | 942.05 | ||
| Fat | 10 | 3 to 20% | 920.39, 954.02, 932.02 | ||
| Fiber | (30 ÷ x) + 6 | 2 to 30% | 962.09 | ||
| Lysine | 20 | 0.5 to 4% | 975.44 | ||
| Moisture | 12 | 3 to 40% | 934.01, 930.15, 935.29 | ||
| Protein | (20 ÷ x) + 2 | 10 to 85% | 954.01, 976.05, 976.06, 984.13 | ||
| Protein, pepsin digest | 13 | all ranges | 971.09 | ||
| Protein, NPN | (80 ÷ x) + 3 | 7 to 60% | 941.04, 967.07 | ||
| Sugar, total as invert | 12 | 24 to 37% | 925.05 | ||
| Minerals | |||||
| Calcium | (14 ÷ x) + 6 | 0.5 to 25% | 927.02, 968.02 | ||
| 10 | 10 to 25% | ||||
| 12 | <10% | ||||
| Cobalt | 25 | 0.01 to 0.16% | 968.08 | ||
| Copper | 25 | 0.03 to 1% | 925.56 | ||
| Fluorine | 40 | as “ppm” | 975.08 | ||
| Iodine | 40 | as “ppm” | 934.02, 935.14 | ||
|
1 x = % guarantee of ingredient or feed. 2 Analytical variance and concentration range based on AAFCO historic check sample data from AAFCO (2018). The table denotes a true analytical variation and not a tolerance. The values apply both above and below the guarantee and are equally correct. 3 Method reference from AOAC (2016). |
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¶ Table 2. Analytical Variance for Analysis of Feed Ingredients and Feeds |
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| Analysis | Analytical variance, %1,2 | Concentration range2 | Determination method3 | ||
| Minerals | |||||
| Iron | 25 | 0.01 to 5% | 968.08 | ||
| Magnesium | 20 | 0.01 to 15% | 968.08 | ||
| Manganese | 30 | 0.01 to 15% | 968.08 | ||
| Phosphorus | (3 ÷ x) + 8 | 0.5 to 20% | 964.06, 965.17 | ||
| Potassium | 15 | 0.04 to 8% | 975.03, 925.01 | ||
| Salt | (7 ÷ x) + 5 | 0.5 to 14% | 969.1 | ||
| (15 ÷ x) + 9 | 0.5 to 14% | 943.01 | |||
| Selenium | 25 | as “ppm” | 969.06 | ||
| Sodium | 20 | 0.2 to 4% | AA | ||
| 15 | 0.2 to 4% | ICP | |||
| Zinc | 20 | 0.002 to 6% | 968.08 | ||
| Vitamins | |||||
| Vitamin A | 30 | 1,200 to 218,000 IU/lb | 974.29 | ||
| Vitamin B12 | 45 | all ranges | 952.2 | ||
| Niacin | 25 | 3 to 500 mg/lb | 961.14, 944.13 | ||
| Pantothenic acid | 25 | 4 to 190 mg/lb | 945.74 | ||
| Riboflavin | 30 | 1 to 1500 mg/lb | 970.65, 940.33 | ||
|
1 x = % guarantee of ingredient or feed. 2 Analytical variance and concentration range based on AAFCO historic check sample data from AAFCO (2018). The table denotes a true analytical variation and not a tolerance. The values apply both above and below the guarantee and are equally correct. 3 Method reference from AOAC (2016). |
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Menegat, M. B.,et. al. 2019. Kansas State University Swine Nutrition Guide: Feed Sampling and Analysis. Kansas State Univ. Coop Ext., Manhattan KS. https://www.asi.k to state.edu/research to and toextension/swine/swinenutritionguide/pdf/KSU%20Feed%20Sampling%20and%20Analysis%20fact%20sheet.pdf
AAFCO. 2018. Official Publication of Association of American Feed Control Officials.
AOAC. 2016. Official Methods of Analysis of Association of Official Analytical Chemists International. 18th ed.