A mix component referred to as a tracer is used to assess mix homogeneity or the level of carry-over at industrial sites. There are two types of tracer:
• internal tracers: a formula ingredient
• external tracers: an external agent supplementary to the formula
The methods used to select a tracer to assess mix homogeneity or carry-over at production lines have been discussed in the technical datasheets that describe this kind of assessment (i’Tec_T2 and i’Tec_H1). The strict application of these rules and, in particular, the criterion for inclusion in the positive list, is currently making it impossible to perform such tests. Given the current emphasis within France placed on medicated feeds under Directive 95/69, some veterinary officers-inspectors, and some plants, have resorted to using drug substances to carry out these assessments.
Against this background, this datasheet presents some examples of comparative results between these two types of tracer and lists the pros and cons of their respective usage.