APPARENT DIGESTIBILITY OF SIX NEW NON-GRAIN PROTEIN INGREDIENTS FOR LARGEMOUTH BASS (MICROPTERUS SALMOIDES)

Apparent digestibility of dry matter (ADMD), crude protein (ACPD), crude lipid (ACLD), gross energy (AED) and amino acids (AACA) in methanotroph (Methylococcus capsulatus, Bath) bacteria meal (MBM), cottonseed Clostridium autoethanogenum protein (CAP), Tenebrio molitor meal (TMM), enzyme-treated soy protein (ETSP), Chlorell meal (CM) and cottonseed protein concentrate (CPC) were determined respectively for largemouth bass (Micropterus salmoides). Apparent digestibility coefficients were determined by using a reference diet with 0.1% Yttrium oxide indicator and test diets that contained 70% reference diet and 30% of the test ingredient being evaluated. The largemouth bass with an average body weight of (19.28±0.10) g were randomly divided into 7 groups with 3 replicates per group and 30 fish per replicate. ADMD coefficients of test ingredients ranged from 37.27% to 86.43%, and ADMD coefficients for CAP and MBM (82.77%—86.43%) were significantly higher than TMM, ETSP, CM, and CPC (P<0.05). ACPD coefficients of test ingredients ranged from 79.97% to 88.45%. The higher ACPD coefficients were observed in CAP and MBM (87.44%—88.45%), followed by TMM, which were significantly higher than those of CPC (79.97%; P<0.05); AACA coefficients of test ingredients ranged from 70.52%—90.51%. The variation trend of the AACA coefficients was basically consistent with that of ACPD coefficients. ACLD coefficients of test ingredients ranged from 51.19%—97.48%. The highest ACLD coefficients were observed in CAP and MBM (94.79%—97.48%). ACLD coefficients for TMM, ETSP and CM (63.11%—88.98%) were significantly higher than those of CPC (51.19%; P<0.05). AED coefficients of test ingredients ranged from 43.25% to 85.43%. The highest AED coefficients were observed in CAP and MBM (83.91%—85.43%). AED coefficients for TMM, ETSP and CM (72.09%—80.53%) were significantly higher than those of CPC (43.25%; P<0.05). These results indicate that CAP and MBM are the best protein source for largemouth bass, and TMM, ETSP and CM are also high-quality protein source for largemouth bass.