Barley protein - improving nutrient digestibility for salmon

Trials on Atlantic salmon show that barley protein concentrate (BPC) provides superior protein, lipid, and mineral digestibility, while supporting healthy gut development and reducing phosphorus emissions into the environment.

Barley protein - improving nutrient digestibility for salmon

Nutrient digestibility

A controlled digestibility study was conducted on juvenile salmon comparing a fishmeal-rich control diet with experimental diets replacing 30% of fishmeal with plant proteins, including: barley protein concentrate (BPC), soy protein concentrate (SPC), corn gluten meal (CGM), Hipro sunflower meal (SFM), and guar meal Korma (GMK).

Protein digestibility is a fundamental parameter for evaluating feed ingredients. BPC achieved an apparent protein digestibility coefficient (ADC) of 84.2%, comparable to CGM (83.5%) and GMK (82.6%), and higher than SFM (80.7%). Although slightly lower than SPC (86.7%), BPC's protein digestibility remains well within a competitive range for salmon diets.

The lipid digestibility coefficient of BPC reached a high of 90.9%, indicating that salmon can effectively utilize energy from fats. This level of fat utilization not only meets high energy demands for growth but also outperforms SPC (87.7%), CGM (89.0%), GMK (89.9%), and SFM (86.6%). In terms of energy, the energy ADC of BPC reached 86.0%, demonstrating a stable contribution to total dietary energy. This shows that BPC is an effective ingredient choice when optimizing nutritional balance in salmon feed.

Phosphorus digestibility, a key indicator for environmental sustainability, was highest for BPC at 33.6%, surpassing SPC (30.6%), CGM (29.7%), SFM (24.8%), and GMK (18.6%). This advantage helps reduce phosphorus discharge into the environment, fulfilling ecological protection requirements.

Lysine and amino acid digestibility

Amino acid digestibility trends were consistent with protein digestibility. BPC achieved a lysine ADC of 82.3% (SPC 88.7%; CGM 80.9%; SFM 77.8%). Digestibility coefficients for both methionine and leucine were above 86%, while arginine reached 89.7%. These values confirm that BPC provides a highly digestible source of essential amino acids, supporting balanced diet formulation.

Dietary treatments had only minor effects on distal intestine histology. However, fish fed diets containing BPC tended to have taller villi, higher goblet cell density, and a higher proportion of acidic mucins compared to groups fed lower-quality proteins such as GMK or SFM. This indicates that BPC contributes to maintaining healthy intestinal architecture in salmon.

In other farmed species, BPC demonstrated protein digestibility of 88–92%, fat digestibility of >93%, and phosphorus digestibility of 33–50%, proving its consistency for both freshwater and marine fish. BPC provides competitive protein digestibility and superior phosphorus utilization efficiency, delivering dual nutritional and environmental benefits.