Apparent digestibility of selected feed ingredients for Chinese sucker, Myxocyprinus asiaticus

摘要

Building a reliable database on apparent digestibility of protein sources is critical for accurate feed formulation and reduction of aquaculture wastes. Apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein, crude lipid, gross energy, phosphorus and amino acids for white fish meal (WFM), brown fish meal (native) (BFM), fermented soybean meal (FSBM), extruded soybean meal (ESBM), soybean meal (SBM), cottonseed meal (CM) and rapeseed meal (RM) were determined for Chinese sucker (Myxocyprinus asiaticus) (18.05A plus or minus 0.27g) using a reference diet (RF) and test diets (70% RF diet plus 30% of tested feedstuff) containing 0.5% chromic oxide as an inert marker. WFM had the highest apparent digestibility coefficient for DM (74.5%). For plant products, the ADCs of DM ranged from 54.3 to 71.6%. Protein digestion by Chinese sucker of WFM, BFM, FSBM and ESBM was significantly higher than CM and RM, ranging from 72.8 to 92.3% for plant products, and 90.3 to 91.2% for animal feedstuffs. Lipids from both animal and plant feedstuffs were highly digested by Chinese sucker, ranging from 89.8 to 94.9%. The highest digestibility coefficient of energy was registered for WFM, followed by BFM; and the lowest digestibility coefficient of energy was recorded for CM (P <0.05). The Chinese sucker did utilize dietary phosphorus from the animal feedstuffs (FSBM and ESBM) more efficiently than from plant feedstuffs (SBM, CM and RM), with values ranging from 58.8 to 61.4% and 25.8-56.0%, respectively. Amino acid availability reflected protein digestibility, except for ESBM, for which the availability of some amino acids was lower, possibly because of protein denaturation during processing. Based on the current findings, FSBM and ESBM could be considered as good potential substitutes for FM in diets for Chinese sucker.