Replacement of fishmeal with a microbial single-cell protein induced enteropathy and poor growth outcomes in barramundi (Lates calcarifer) fry

Abstract

Fish meal (FM) replacement is essential for the sustainable expansion of aquaculture. This study focussed on the feasibility of replacing FM with a single-cell protein (SCP) derived from methanotrophic bacteria (Methylococcus capsulatus, Bath) in barramundi fry (Lates calcarifer). Three isonitrogenous and isoenergetic diets were formulated with 0%, 6.4% and 12.9% inclusion of the SCP, replacing FM by 0%, 25% and 50%. Barramundi fry (initial body weight 2.5 ± 0.1 g) were fed experimental diets for 21 days to assess growth performance, gut microbiome composition and gut histopathology. Our findings revealed that both levels of SCP inclusion induced detrimental effects in barramundi fry, including impaired growth and reduced survival compared with the control group (66.7% and 71.7% survival in diets replacing FM with SCP by 25% and 50%, respectively; p