Survival and protein synthesis of post-larval White Shrimp, Litopenaeus vannamei were affected by dietary protein level

Abstract

A 25-days experiment was conducted to evaluate the effect of dietary protein levels on growth, survival, digestive enzymes and protein synthesis of post-larval Litopenaeus vannamei. Post-larval white shrimp (mean initial weight 2.1 mg) were fed five isoenergic diets containing gradient levels of protein (456, 469.9, 484.6, 501.4, 512.9 g/kg). Results indicated that 501.4 g/kg dietary protein increased the survival of post-larval white shrimp. Special growth rate (SGR) and weight gain (WG) showed no difference among each group. Whole body protein contents increased with the dietary protein increased to 484.6 g/kg. The relative mRNA levels of trypsin and chymotrypsin also increased with the dietary protein increased to 484.6 g/kg. Target of Rapamycin (TOR) and eukaryotic translation initiation factor 4E-binding protein (4EBP) mRNA expressions were significantly higher in shrimp fed the 484.6 g/kg dietary protein than other groups. The mRNA expression of two important translation initiation factors eukaryotic translation initiation factor 4E (eIF4E) and eukaryotic translation initiation factor 3k (eIF3k) were increased with the increasing dietary protein levels. Three endoplasmic reticulum (ER) stress related genes (eIF2α, XBP1 and ATF4) expression also increased with the dietary protein increased to 484.6 g/kg. These results clearly indicated that proper dietary protein improved the survival, and enhanced the protein synthesis of post larval white shrimp. Quadratic regression analysis based on survival indicated that the optimal dietary protein level of post-larval white shrimp was 495.8 g/kg.