BioMar Retention Technology

BRT research and development

The development of BRT generated extensive documentation in all areas where the production process is important for the performance potential of the feed. We work continuously to optimise the production chain from feed raw material through to the fish being slaughtered.



The result is that a high degree of process competence focusing on all levels in the chain from raw material to fish is a prerequisite for full utilisation of the performance potential of the feed.

Process and raw materials

Control of pellet durability - extract from documentation
The durability is changed with unchanged process parameters if the level of the same raw material is changed.

Effect of process parameters 1 and 2 on durability - DORIS %

  • Doris value for salmon feed must be high
  • Highest Doris % value with dark blue colour in the figures = high durability
  • x-axis = process parameter 1, y-axis = process parameter 2

Process and formula

Control of pellet quality - extract from documentation
The pellet quality changes with different process parameters and unchanged formula.


Process and storage of feed

Control of storage stability - extract from documentation
Pellet stability during storage is affected by drying, the process and the pellet structure Feed with a high DORIS percentage retains more stability.

Storage effect with increasing water content in the feed - DORIS %

  • Increasing water content left to right.
  • Effect of water content and process combinations – DORIS %
  • Better storage stability with high DORIS percentage is documented in many trials with both commercial feed and trial feed.

Storage effect with different process conditions - DORIS %


Robustness in feeding system

Pellet durability and blowing effect - extract from documentation
Increased durability in feeding system with increasing water content (and DORIS %) in feed.
Increased durability in feeding with reduced blowing effect from 100% to 75%.

Durability with feeding with 75% blowing effect

Increasing water content (and DORIS % *) left to right.

  • Effect of 75% blowing effect (light columns) and 100% blowing effect (dark columns).
  • Especially good effect of 75% blowing effect at lower DORIS %.
  • *DORIS measuring during production of feed

Durability with feeding with 100% blowing effect

Species differences

Special adjustment for different species - extract from documentation

1) Pellet structure

Process must be adapted for optimum performance and intestinal health. Different requirements in terms of pellet structure.

Process and raw material knowledge for optimum pellet quality adjusted to different species. For example, salmon and trout have different needs that can effect digestibility and nutrients, fat gulping with trout and undigested pellets with salmon.

2) Digestion of starch
Raw materials and raw material levels have different effects on digestion of nutritional components. Starch level gives different effects on starch digestion in salmon and trout.

Digestion (ADC) of starch with increasing content of starch in the feed. Different effect of the same diet in salmon and trout.

Conclusions from BRT documentation

See below for some conclusions from BRT work shown above. The material in its entirety is very extensive, and this is only one introduction to the broad subject area covered by BRT.

A comprehensive analysis of the material can be obtained by contacting BioMar.


Raw material quality and quantity have an important influence on pellet quality

Process parameters
must be specific
for correct product quality

Process conditions are optimised for different raw materials

Correct measurement of pellet quality is crucial for production of optimum feed

Optimum pellet quality is stable during handling, feeding and storage

Correct adjustment of the feeding system reduces feed waste

The feeding system can be adjusted to the physical quality of the feed

There are differences between species in nutrient digestion and requirements in terms of pellet structure.

Pellet quality is important for intestinal health in farmed fish 

Pellet quality is important for nutrient intake in fish