Substitution of soybean meal with Clostridium autoethanogenum protein in grass carp (Ctenopharygodon idella) diets: Effects on growth performance, feed utilization, muscle nutritional value and sensory characteristics

Abstract

Iso-nitrogenous and iso-lipidic diets replace 0 %, 30 %, and 100 % of soybean meal (SBM) with Clostridium autoethanogenum protein (CAP) (namely, CAP0, CAP30 and CAP100) were prepared to evaluate their effects on the growth performance, feed utilization, muscle nutritional value and sensory characteristics of grass carp. The results indicated that the growth performance and feed utilization of grass carp fed a diet containing CAP groups were comparable to those of the control group (P > 0.05). However, CAP-containing diet enhanced pH, cohesiveness, springiness, gumminess and chewiness of muscle (P < 0.05), thereby improving the muscle physical properties. The CAP100 group did not affect the muscle content of crude protein and crude fat (P > 0.05), nevertheless it increased the content of essential and non-essential amino acids (P < 0.05), which improved the nutritional value of grass carp muscle. The CAP30 group promoted the synthesis of proteins in grass carp by regulating rapamycin signaling pathway which increased the crude protein content in muscle. Meanwhile, the CAP30-containing diet upregulated the expression of genes myogenic factor 5 (Myf5), myogenic regulatory factor 4 (Mrf4), myogenin (MyoG), myogenic determining factor (MyoD) and myosin heavy chain (MyHC) proteins which participate in muscle growth and development of the muscle. Compared with the control group, the tenderness and the content of inosinic acid in the CAP100 group muscle were increased (P < 0.05), and the content of volatile compounds which regulate fishy smell was decreased in muscles in the CAP100 group (P < 0.05). Collectively, our results indicated that CAP improved the nutritional value and sensory properties of the muscle without affecting the growth performance and feed utilization of grass carp.