Evaluation of single cell protein on the growth performance, digestibility and immune gene expression of Pacific white shrimp, Penaeus vannamei

Growth and digestibility trials were undertaken to evaluate a single cell protein (SCP) produced from methane-oxidising bacteria Methylococcus capsulatus (String Bio, Bengaluru, India) as a replacement for fishmeal in the diets of Pacific white shrimp, Penaeus vannamei. Five isonitrogenous and isoenergetic diets were formulated to contain different levels of SCP: Control (Fishmeal, no SCP), SCP inclusion at 50 g/kg (S-5), 100 g/kg (S-10), 200 g/kg (S-20), 250 g/kg (S25). The final body weight of the shrimp increased with increasing levels of SCP up to 200 g/kg (S-20) and recorded the best feed efficiency when compared to other treatments. Nitrogen (N) and phosphous (P) gain and retentions were improved in shrimp fed diets containing upto 200 g/kg SCP. There was no significant difference in the whole-body chemical and amino acid composition of shrimp. Apparent protein digestibility of the SCP was greater than 0.90. The expression levels of immune-relevant genes (lysozyme, Toll-like receptor and immune deficiency (IMD)) were upregulated in the shrimp fed diet S-20. Results of this work demonstrate that SCP from M. capsulatus can be efficiently used in the diet of P. vannamei up to 200 g/kg (two-thirds of fishmeal replacement) with significant beneficial effects on growth, feed and nutrient utilisation.

Automated summary

The study found that a single cell protein (SCP) produced from methane-oxidising bacteria Methylococcus capsulatus can replace fishmeal in the diets of Pacific white shrimp, Penaeus vannamei. Shrimp fed diets with increasing levels of SCP up to 200 g/kg showed improved growth and feed efficiency. Nitrogen and phosphorous retention in shrimp were also improved with SCP inclusion in the diets. The study demonstrated that SCP from M. capsulatus can be efficiently used in the diet of P. vannamei up to 200 g/kg with significant beneficial effects on growth, feed and nutrient utilization.