Enhancing Hybrid Abalone Growth with Methanotrophic SCP

Benefits of Methanotrophic Single Cell Protein in Aquaculture

Methanotrophic SCP, derived from methanotrophic bacteria, presents a sustainable alternative to traditional protein sources in aquaculture. The advantages of incorporating methanotrophic SCP include:

High Protein Content: SCP typically exhibits a protein concentration exceeding 70%, making it an excellent protein source for abalone, which require high protein diets for optimal growth (Salini et al., 2025).
Sustainability: The production of SCP from methane utilizes a gas that is often considered a waste product, thus reducing the environmental impact associated with conventional protein sources like fishmeal and soy protein concentrate (Glencross et al., 2020).
Nutritional Profile: SCP contains a balanced amino acid profile, essential for the growth and health of aquatic species. Research indicates that SCP can support comparable growth rates to traditional protein sources at lower inclusion levels (Hassan et al., 2023).
Reduced Antinutritional Factors: Unlike some plant-based proteins, SCP has minimal levels of antinutritional factors, potentially leading to better digestibility and absorption in abalone.

Optimal Inclusion Levels for Australian Hybrid Abalone Diets

Determining the optimal inclusion level of SCP in abalone diets is essential for maximizing growth performance and feed efficiency. In a study conducted by Salini et al. (2025), abalone were fed diets containing varying levels of SCP:

Diet Inclusion	Final Weight (g)	Weight Gain (%)	FCR
0% SCP	20.5 ± 0.5	110 ± 5	1.2
5% SCP	20.7 ± 0.4	112 ± 4	1.1
10% SCP	20.6 ± 0.6	111 ± 3	1.0
20% SCP	19.0 ± 0.5	85 ± 6	1.5

The results indicated that abalone fed diets with up to 10% SCP performed similarly to those fed a control diet without SCP. However, the inclusion of 20% SCP resulted in a significant decrease in performance parameters, including final weight and weight gain percentage, suggesting that high levels of SCP may negatively affect palatability or digestibility.

Impact of Protein Hydrolysate on Feed Palatability

To address potential palatability issues associated with high SCP inclusion levels, researchers explored the use of commercially produced protein hydrolysate (PH) as an additive. Although protein hydrolysates are known to enhance feed acceptance in various aquatic species, the study by Salini et al. (2025) found that adding PH did not significantly improve growth performance or feed intake for abalone fed with 20% SCP. This suggests that while PH can enhance palatability, it may not fully mitigate the adverse effects of high SCP inclusions.

Assessing Feed Utilization and Digestive Efficiency

Evaluating feed utilization and digestive efficiency is crucial for optimizing feed formulations in aquaculture. In the study, the apparent digestibility (AD) of diets was measured to assess how efficiently abalone could utilize the nutrients provided:

Diet Inclusion	AD of Dry Matter (%)	AD of Protein (%)	AD of Energy (%)
0% SCP	70 ± 3	72 ± 2	75 ± 4
5% SCP	68 ± 2	70 ± 3	72 ± 3
10% SCP	69 ± 4	74 ± 3	76 ± 2
20% SCP	64 ± 5	65 ± 4	70 ± 4

As depicted in the table, the AD of dry matter, protein, and energy decreased significantly at the 20% SCP inclusion level, which aligns with the observed reduction in growth performance. This decline may be associated with the high nucleic acid content in SCP, which could affect nutrient absorption and overall digestive efficiency.

Comparative Analysis of Growth Performance and Nutritional Value

The comparative analysis of growth performance and nutritional value highlights the significance of SCP in abalone diets. The findings indicate that while SCP can be effectively used as a protein source, its inclusion should be limited to 10% to prevent adverse effects on growth and feed efficiency. Moreover, the study emphasizes the need for further investigation into optimizing SCP formulations and the potential for combining SCP with other feed additives to enhance overall performance.

Parameter	Control (0% SCP)	10% SCP	20% SCP
Final Weight (g)	20.5 ± 0.5	20.6 ± 0.6	19.0 ± 0.5
Weight Gain (%)	110 ± 5	111 ± 3	85 ± 6
FCR	1.2	1.0	1.5
AD of Dry Matter (%)	70 ± 3	69 ± 4	64 ± 5
AD of Protein (%)	72 ± 2	74 ± 3	65 ± 4

Conclusion

The integration of methanotrophic SCP into the diets of Australian hybrid abalone presents a promising avenue for enhancing aquaculture sustainability. However, optimal inclusion levels should be carefully managed to ensure maximum growth performance and feed efficiency. Further research is warranted to explore the interplay between SCP and other feed ingredients, as well as the potential benefits of additional palatability enhancers in abalone diets.

FAQ

What is methanotrophic SCP? Methanotrophic single cell protein (SCP) is derived from methanotrophic bacteria that utilize methane as a carbon source, offering a sustainable and high-protein alternative to traditional feed ingredients.

What are the optimal inclusion levels of SCP in abalone diets? Research suggests that the optimal inclusion level of SCP in Australian hybrid abalone diets should not exceed 10% to avoid negative impacts on growth performance and feed efficiency.

How does protein hydrolysate affect feed palatability? Protein hydrolysate can enhance feed palatability; however, in studies involving abalone, it did not significantly improve growth performance when included with high levels of SCP.

What factors affect the apparent digestibility of diets? Factors that influence the apparent digestibility of diets include the type of ingredients used, processing methods, and the feeding behavior of the species being cultured.

Why is it important to assess feed utilization in aquaculture? Assessing feed utilization is crucial for optimizing feed formulations, ensuring that aquatic species receive the necessary nutrients for growth while minimizing waste and environmental impact.

References

Salini, M. J., Wang, W., Mock, T. S., Siddik, M. A. B., Jago, M. K., Bews, K. L. F., & Francis, D. S. (2025). Expanding the Ingredient Basket in Aquaculture: Growth Performance and Feed Utilization of Australian Hybrid Abalone (Haliotis laevigata × H. rubra) Fed Methanotrophic Single Cell Protein. Aquaculture Nutrition. https://pubmed.ncbi.nlm.nih.gov/11893209/
Glencross, B. D., Huyben, D., & Schrama, J. W. (2020). A Feed Is Still Only as Good as Its Ingredients: An Update on the Nutritional Research Strategies for the Optimal Evaluation of Ingredients for Aquaculture Feeds. Aquaculture Nutrition. https://pubmed.ncbi.nlm.nih.gov/11893192/
Hassan, A. L. I., Mock, T. S., & Searle, K. (2023). Growth Performance and Feed Utilisation of Australian Hybrid Abalone (Haliotis rubra × Haliotis laevigata) Fed Increasing Dietary Protein Levels at Three Water Temperatures. British Journal of Nutrition. https://pubmed.ncbi.nlm.nih.gov/11893210/