The Need for Larger Analytical Samples with Granulated Feed Additives

Abstract

Sampling an animal feed containing a granulated analyte is extremely difficult. A granulated feed additive, Tylan (Elanco, tylosin), was used to demonstrate how a granulated product can increase assay variability if steps are not taken to reduce and control this variability. The number of tylosin granules was determined for Granulated Tylosin Concentrate, the active ingredient of Tylan Premix. Multiple weighings of 3 lots of the concentrate were prepared, and the average number of granules per gram of concentrate was determined with the aid of image analyses. The total weight of Tylan Premix in varying analytical samples was calculated. Finally, the average number of tylosin granules per analytical sample was calculated based on the average number of granules per gram. A 10 g analytical sample obtained from an animal ration containing 8 ppm tylosin activity would contain an average of 1.16 granules of tylosin, and a 100 g analytical sample would contain 11.6 granules. These calculations demonstrate the need to increase the analytical sample size in analyzing an animal feed containing a granulated feed additive.