# A New Protocol for Homogeneity Testing in Feed Mill Concentrate Rations

## TL;DR

This paper introduces a new method to test if animal feed is mixed properly using potassium and magnesium as markers and a simple sampling protocol.

## Contribution

A new protocol for homogeneity testing in feed mills using potassium and magnesium as reliable markers and a simplified statistical approach.

## Key findings

- Potassium and magnesium show low variability and are effective markers for feed homogeneity.
- A ratio of less than 1.26 between mineral levels in two samples indicates proper mixing.
- The protocol involves sampling at specific times during mixer discharge for accurate evaluation.

## Abstract

Ensuring that animal feed is well mixed is essential for producing safe and consistent rations in feed mills. To find the best way to check whether the feed is properly mixed, we carried out a study in a commercial feed mill, tested different markers, and proposed a sampling method and statistical approach for a ration homogeneity test. We found that the minerals potassium and magnesium work very well as markers of how evenly the feed is mixed. When mixing is performed correctly, the amount of these minerals changes very little from one mixer, batch, or sample to another. Because of this low variation, they are reliable for identifying when the mixing process is not working as it should. Based on these results, we developed a simple protocol to evaluate the quality of the mixing process: two samples are taken from each batch—one early and one later during the mixer’s discharge. The levels of potassium or magnesium in these samples are then measured. If the ratio between the highest and lowest mineral levels is smaller than 1.26, the ration is considered properly mixed. If the difference is larger, it suggests a mixing problem, meaning that the process or the equipment needs to be checked.

To ensure an accurate homogeneity test, animal feed manufacturers should apply standardised techniques and procedures, which aim to guarantee the product quality. Our objective was to propose a new protocol for performing concentrate ration homogeneity tests in commercial feed mills, based on three main points: the suitability of different minerals as markers; establishing a simplified and reliable sampling protocol; and developing a simplified statistical approach for evaluating marker dispersion among increments. Four horizontal commercially available mixers were used. Increments were collected sequentially during the mixer-emptying time over five consecutive days, totalling 200 increments, in which nine potential mineral markers were evaluated. The minerals potassium (K) and magnesium (Mg) were considered suitable, as they simultaneously exhibited low variability among batches, among mixers, and among increments. Based on the variation patterns of K and Mg, the new protocol for homogeneity testing in feed mill concentrate rations is based on the following additional key points: two increments must be collected per ration batch, taken during the mixer-emptying operation—specifically at the second and eight tenths of the mixer-emptying time, and a concentrate ration mixture is considered homogeneous when the ratio between the highest and lowest marker contents in the increments is lower than 1.26.