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The Importance of Particle Characterization within the Feed Manufacturing Process


A commonly held misconception within the feed manufacturing process is that all feed ingredient particles are smooth spheres differing only in size. However, nothing is farther from the truth. The reality is that feed ingredient particles can be imagined as a mixture of dented and bruised microscopic bee bees, baseballs, beachballs, boulders, toothpicks, two-by-tens, and tree trunks with varying sizes of plywood mixed in for good-measure! In addition, all feed ingredients are a composite of solids, moisture and gases. The moisture and gases that are interspersed throughout the feed ingredient will have a large influence on ingredient flowability during manufacturing.


Specific to the growing use of phytogenic-based technologies, these feed ingredients are typically processed and manufactured in one of two ways. The first and easiest way is to simply shred the plant and then expose it to sunlight (generally outside in an open-air field) until the moisture is reduced to the desired level. The shredded log is then pulverized and ground to the desired product consistency, at which point, it is ready for packaging and marketing (i.e., whole ground log…WGL). As a result of this process, the wood fiber acts as a carrier for the active components within this fibrous product. This is the cheapest processing method, but also returns the lowest value when used in livestock feeds.

The alternative method is to mechanically extract the liquid from the plant, and filter, condense and concentrate it into a consistent material. The liquid extract is then transported and either marketed as a liquid technology or further processed into a stable, dry technology that is packaged and marketed (i.e., Micro-Aid®…MAFGC). Although this processing method requires a greater investment, it is easily offset by the resulting higher-quality product yielding more consistent animal performance and a higher return on investment.

Particle Characterization

Typically, the feed industry has used some rather “low-tech” methods to characterize feed ingredient particles, including sieve analysis and angle of repose.

Although the particle size of corn and soybean meal can vary a great deal, the average particle size of corn going through mills manufacturing feed for poultry and pigs is about 500 ± 100 microns, while soybean meal is around 900 microns.

The angle of repose of a material is the steepest angle of descent or dip relative to the horizontal plane to which a material can be piled without sliding. Ingredients that do not flow well, have a greater (steeper) angle of repose.

Advancements in particle characterization capabilities have resulted in a more comprehensive understanding of the differences among phytogenic feed ingredients.

Current microscopic techniques (e.g., Malvern G3S) allow for 3-D imaging that provides measures such as circularity and aspect ratio (particle width to length), circular index.

Another current instrument involves the use of a Freeman Technology FT4 Powder Rheometer, which analyzes for Basic Flowability Energy (BFE), Specific Energy (SE), Conditional Bulk Density (CBD), Compaction Energy (CE), Consolidation Index (CI), and compressibility of the ingredients.

Micro-Aid Feed Grade Concentrate (MAFGC) vs. Whole Ground Log (WGL)

What can be concluded from the analysis of MAFGC vs. a WGL product is:

  • The average particle size of WGL is 1/10 the size of MAFGC (and for ground corn)
  • WGL has a greater angle of repose than MAFGC
  • Particle characteristics (size, shape, roughness, electrostatic charge, etc.) of WGL create cohesiveness
  • Particles of WGL are more elongated than the particles within MAFGC -Not longer-than!
  • More elongated particles arrange in layers when subjected to tapping or compression and exhibit a greater degree of compressibility
  • More elongated particles trap more gas between particles resulting in a lower bulk density
  • MAFGC particles are more circular than the particles within WGL.
  • More circular particles tend to be less cohesive
  • Ingredients with more circular particles are less susceptible to compressibility by tapping or compression
  • Ingredients with more circular particles tend to have a greater bulk density
  • WGL had the lowest Basic Flowability Energy (BFE)…particles are very small and less dense
  • Infers that WGL particles can easily become air-born = dust
  • WGL had a high SE and is close to being classified as a “High Cohesion” ingredient
  • The change in energy needed to displace WGL after consolidation by tapping or pressure was 3 to 7X greater than the change in energy required to displace MAFGC after consolidation
  • WGL was severely negatively affected by compression…Implies caking in bags stacked in pallets

DPI GLOBAL has invested significant effort in developing and enhancing these phytogenic-based technologies for use as a feed ingredient. As a result, these superior particle characteristics of Micro-Aid® Feed Grade Concentrate result in a product that is less dusty, exhibits better flowability out of micro-bins within feed mills and becomes more evenly distributed within complete feed. Please contact your feed representative or DPI GLOBAL to identify how you can benefit from this value.

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