Effects of partially replacing fish meal with three types of enzymatic hydrolysis of animal protein on muscle quality of Litopenaeus vannamei

Due to the current global shortage of fishmeal resources and the increasing demand, the development of new protein sources has become crucial for the sustainable development of Chinese aquaculture industry. The aim of this experiment is to investigate the effects of three enzyme hydrolyzed proteins (enzyme hydrolyzed fish fillet, enzyme hydrolyzed chicken liver, and enzyme hydrolyzed black soldier fly) replacing 5% fish meal on the muscle quality of Litopenaeus vannamei. 480 evenly sized shrimp with an initial weight of (0.31 ± 0.01) g were randomly divided into 3 groups, with 3 parallel shrimp in each group and 40 shrimp in each parallel group. They were fed with a basic feed (CON group) consisting of enzymatic hydrolysate of fish fillet (EHFF group), enzymatic hydrolysate of chicken liver (EHCL group), and enzymatic hydrolysate of black soldier fly group (EHBF group) as substitutes for 5% fish meal in the nitrogen equivalent feed. The experiment lasts for 8 weeks. The results showed that: ① The crude fat of the whole shrimp in EHFF group was significantly higher than that in CON group, while there was no significant difference in the crude fat of shrimp muscle; There was no significant difference in the crude fat of the whole shrimp and shrimp muscle between EHCL group and CON group; The crude fat of the whole shrimp and shrimp muscle of the EHBF group were significantly lower than those of CON group, and the collagen content in the shimp muscle was significantly higher than that of the other groups. ② The springness, gumminess, chewiness, and hardness of shimp muscle of EHBF group were significantly higher than those of the other groups, while there was no significant difference between EHFF group, EHCL group, and CON group. ③ In terms of muscle histology, the interval between muscle fibers in EHBF group was slightly smaller than that in CON group, and there is no significant difference in fiber diameter and fiber structure density of shimp muscle between EHBF group and CON group. ④ The relative mRNA expression levels of myosin genes myh1 and myh2 in EHFF group were significantly lower than those in CON group, while the relative mRNA expression level of myh1 in EHCL group was significantly higher than that in CON group. There was no significant difference in the relative mRNA expression level of myosin genes between EHBF group and CON group. The relative expression level of collagen gene col1a1 mRNA in EHBF group was significantly higher than that in CON group. In summary, adding enzymatic hydrolysis of black soldier fly can reduce the fat content of shrimp muscles, increase the collagen content in muscles, and have a significant promoting effect on the muscle quality of Litopenaeus vannamei.