Inclusion of metabolites extract (ME) of non-pathogenic Escherichia coli in fish feeds could enhance fish growth and gut health, resulting in high yield. However, there is scanty information on its utilization particularly in aquaculture feeds. Therefore, this study investigated the growth and gut health potentials of non-pathogenic E. coli metabolites in the diets of African catfish (Clarias gariepinus).
Fish (8.80±0.36g; n = 255) were randomly assigned into 15 tanks in a completely randomized design and fed non-pathogenic Escherichia coli metabolites diets of 40% crude protein containing 0.0g/kg (ME0), 5.0g/kg (ME1), 10.0g/kg (ME2), 15.0g/kg (ME3), and 20.0g/kg (ME4) at 3% body weight for 12 weeks to determine the weight gain (WG, g), specific growth rate (SGR, %g/day) and feed conversion ratio (FCR). Gut morphometric characteristics and microbial loads were assessed. Blood was sampled to determine pack cell volume (PCV, %), white blood cells (WBC, 106/µL), alanine transaminase (ALT, IU/L). Economic values (EVs) were also estimated, and all data analyzed using ANOVA at α0.05.
Highest WG (55.7±0.5), SGR (2.3±0.0), and least FCR (1.3±0.0) occurred in ME2 fed Clarias gariepinus. Villi height and width ranged from ME2 (3336.95±12.88) to ME1 (1340.00±277) and ME2 (442.60±109.60) to ME1 (189.60±62.00) respectively. TVC ranged from ME0 (45.3±16.5) to ME4 (16.6±1.5). Escherichia coli (14.00±7.94) and Vibrio species (28.00±12.82) were highest in ME0 and least in ME2 (2.6±4.6 and 7.8±7.7, respectively). The PCV was highest in ME2 (31.0±2.8), WBC (24.0±38.5) highest in ME1, and ALT highest in ME3 (21.9±0.7). The EVs ranged from ME2 (1.19) to ME0 (0.00). Therefore, this implies that 1.0% ME per kg diet inclusion had better yield performance.
In conclusion, diets containing 1.0% ME per kg inclusion enhanced growth, morphometric indices (villi height and width), and also improved economic values.