Abstract:The present study aimed to investigate the effects of dietary protein level on the growth performance, feed efficiency, and immuno-enzymatic activity in Paramisgumus dabryanus ssp. Four diets were formulated with 25%, 30%, 35%, and 40% protein, respectively. In total, 720 P. dabryanus ssp with an initial body weight of (8.57±0.35) g were randomly divided into 4 groups with 3 replicates per group and 60 fish per replicate. The cultivation of P. dabryanus ssp lasted for 60 d feeding with the four diets. The results showed that the final weight (FW), specific growth rate (SGR), and feed efficiency rate (FER) of P. dabryanus ssp increased with increase in dietary protein level, and plateaued at the dietary protein level of 35%. Initially, the protein efficiency ratio (PER), protein retention (PRE), and survival rate (SR) increased, and then started to decrease. However, the feeding rate (FR) showed a gradual decrease with increasing dietary protein level. The results of broken line simulation of FW, SGR, and FER showed that the P. dabryanus ssp had the optimal growth and feed efficiency rates at a dietary protein levels between 34.57% and 35.37%. Furthermore, the quadratic polynomial regression analysis revealed that the utilization of protein by the P. dabryanus ssp reached the highest level at the dietary protein levels between 33.61% and 34.68%. The activity of superoxide dismutase (SOD) in P. dabryanus ssp increased at first and then plateaued with increasing dietary protein level. The activity of catalase (CAT) in the P. dabryanus ssp increased at first and then decreased. The activity of glutamic oxaloacetic transaminase (GOT) and glutamate pyruvic transaminase (GPT) in the P. dabryanus ssp increased at first and then decreased with increase in dietary protein levels. These results show that a suitable dietary protein level can improve the growth rate, feed efficiency, and immuno-enzymatic activity of P. dabryanus ssp. Furthermore, a comprehensive analysis of growth performance, feed efficiency, and immunity-related enzyme activity revealed that the optimal dietary lipid level for P. dabryanus ssp is 34.68%~35.37%.
