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Application of Analytical Variances to Laboratory Findings on Feed Samples

When a feed sample is analyzed in the laboratory of the State Chemist, the findings show the samples either meeting or falling outside of label guarantee. Where the findings fall outside guarantee, the sample is not automatically classified as being violative under the law, however. A variance factor is applied to the laboratory results before making such a determination. The factor attempts to account for error which could have been made during sampling and analysis of the product. Only when the laboratory finding falls outside the value provided by applying the variance factor to the guarantee is the sample considered in violation. The variance factor is not a tolerance, in that it is applied only to individual samples. If a pattern of falling only slightly within the variance factor, but below guarantee is established over multiple samples, this indicates a manufacturer problem and such would be called to his attention for correction.

It is known that even with the use of accepted good manufacturing practices, occasional failure to meet label guarantees upon application of the appropriate variance factor to laboratory data will be seen in those feeds which are acquired for analysis. While each of such instances will be called to the manufacturers attention, through issuance of reports, this office seeks in its sampling program to establish confidence that manufacturers have reasonable controls in place to assure an ongoing conformance of products to label guarantees in a high percentage of samples acquired. When this is not evident, regulatory procedures will be invoked.

The Association of American Feed Control Officials (AAFCO) has for many years recommended a set of analytical variances to be applied to laboratory results on feeds. These variances were arrived at through the AAFCO monthly laboratory check sample program and are scientifically based, having been established from evaluation of thousands of laboratory analyses for each guarantee. Texas did not actively use the AAFCO variances prior to September 1, 1986, although notice was provided in the 1974-75 annual report on commercial feed that, subsequent to that time, these variances would be employed.

Use of the AAFCO variances was put into effect in Texas on September 1, 1986 after first comparing them on several sets of laboratory data with the variances previously employed by the Feed and Fertilizer Control Service. The variances on some guarantees were made less stringent under the AAFCO system, others more so. On balance, however, there appeared to be no effect on violation rate by making the change to the AAFCO system.

Upon accumulation of the year-end information (FY 87), however, it became evident that so-called "minor violations" had increased by 12%, most notably in protein and vitamin A guarantees, both of which have smaller allowable variances under the AAFCO system. Since approximately 90% of all feed samples are analyzed for protein and a very large number are also assayed for vitamin A content, the weight of values from these analyses tended to shape the overall system and made it appear to have tighter variances overall.

Since this effect was not anticipated and so as to be fair to all concerned, the AAFCO variances for protein and vitamin A were suspended for a period of two years (until September 1, 1989) to provide the industry with sufficient time to become familiar with and prepared for that period. During this period, the previous Control Service variances for protein and vitamin A were left in place. All other AAFCO variances are in use. Copies of these variance may be obtained from the Control Service or the current official publication of the AAFCO.

Analytical Record for Individual Component Guarantees of Sampled Feed Drugs/Antibiotics Analyte Name Total Non Violative Violative Percent Violative AMPROLIUM 0 0 0 0.0 BACITRACIN METHYLENE DISAL. 0 0 0 0.0 BACITRACIN ZINC 0 0 0 0.0 CHLORTETRACYCLINE 2 1 1 50.0 DECOQUINATE 88 74 14 15.9 ETHOPABATE 0 0 0 0.0 LASALOCID SODIUM 63 51 12 19.0 MONENSIN 74 67 7 9.5 NEOMYCIN BASE, 0 0 0 0.0 NITARSONE 0 0 0 0.0 OXYTETRACYCLINE 0 0 0 0.0 SULFAMETHAZINE 0 0 0 0.0 TYLOSIN 0 0 0 0.0 General Analyte Name Total Non Violative Violative Percent Violative ACID DETERGENT FIBER 0 0 0 0.0 ASH 0 0 0 0.0 CRUDE FAT 81 79 2 2.5 CRUDE FIBER 0 0 0 0.0 CRUDE PROTEIN 3672 3407 265 7.2 LYSINE 0 0 0 0.0 METHIONINE 0 0 0 0.0 MICROSCOPY 47 41 6 12.8 MOISTURE 0 0 0 0.0 NPN (NON-PROTEIN NITROGEN) 3 3 0 0.0 TOTAL NITROGEN 0 0 0 0.0 VITAMIN D NO RPT 9 8 1 11.1 Minerals Analyte Name Total Non Violative Violative Percent Violative AMMONIUM CHLORIDE AS NPN 0 0 0 0.0 BORON 0 0 0 0.0 CALCIUM 1354 1269 85 6.3 CHLORINE 0 0 0 0.0 COPPER (nutrient) 1003 922 81 8.1 IRON 73 73 0 0.0 MAGNESIUM 182 174 8 4.4 MANGANESE 124 121 3 2.4 PHOSPHATE, AVAILABLE 0 0 0 0.0 PHOSPHORUS 446 400 46 10.3 POTASSIUM 397 389 8 2.0 SALT 130 104 26 20.0 SELENIUM (nutrient) 88 88 0 0.0 SODIUM 72 69 3 4.2 SOLUBLE POTASH 0 0 0 0.0 SULPHUR IN FERTILIZER 1 1 0 0.0 ZINC 252 241 11 4.4 Mycotoxins Analyte Name Total Non Violative Violative Percent Violative AFLATOXIN 741 713 28 3.8 FUMONISIN 462 458 4 0.9 FUMONISIN B1 0 0 0 0.0 Vitamins Analyte Name Total Non Violative Violative Percent Violative VITAMIN A 541 416 125 23.1