RESUMO
The study was carried out to investigate Cordyceps militaris spent mushroom substrate (CMSMS), a renewable biomass, for its effect on fish as an alternative source of in-feed antibiotics. For meticulous examination, four different iso-nitrogenous and iso-caloric diets were prepared containing CMSMS at 0%, 1%, 2%, and 3%. A total of 360 Labeo rohita fingerlings with an average initial weight and length of 12.6 ± 0.04g and 10 ± 0.1 cm, respectively, were blocked into 4 treatments with 3 replicates, i.e., T1 (control), T2 (10 g/kg), T3 (20 g/kg), and T4 (30 g/kg). The feeding trial was conducted for 60 days with samplings on the 7th, 15th, 30th, and 60th days, and blood samples were collected to determine different immunological (NBT, TIg, lysozyme, and antiprotease activity) and biochemical (glucose, total protein, SGPT) parameters. A challenge study was conducted against Aeromonas hydrophila at the end of the feeding trial. The results showed that CMSMS at 30g/kg showed a better immune response over time with increasing doses. All the biochemical readings fall within normal ranges. Fish fed with CMSMS at 30g/kg (3%) have better survival after being challenged with Aeromonas hydrophila. Therefore, Cordyceps militaris spent mushroom substrate (CMSMS) can be biosafely used as in-feed antibiotics in Labeo rohita and can reduce the concern of by-product disposal from mushroom cultivation.
