Growth and metabolomic responses of Pacific white shrimp (Litopenaeus vannamei) to different dietary fatty acid sources and salinity levels

The outstanding benefits of and strong interest in the inland low-salinity culture of penaeid shrimp have led to the growth of this industry worldwide. This study aimed to explore the effects of dietary fatty acids on shrimp in low-salinity culture. Individuals of the marine white shrimp Litopenaeus vannamei were fed one of three diets (coconut oil, fish oil, or an equal mixture of both) of differing fatty acid profiles for eight weeks while being maintained at two different salinities (3 or 30 psu). Then, a GC-TOF/MS-based metabolomics analysis was performed to reveal the regulatory roles of fatty acids in shrimp growth, survival and osmoregulation at two salinities. The shrimp fed the mixed oil diet had higher weight gain and survival, and those fed the diet with only fish oil added exhibited higher unsaturated fatty acid levels in the gills and hepatopancreas irrespective of salinity. Na⁺/K⁺-ATPase and total ATPase activities were lowest in the shrimp fed the mixed oil diet at both salinities. When coconut oil was the only lipid source, shrimp tissues contained higher tyrosine, lysine and serine levels at 3 psu than at 30 psu. In contrast, the shrimp fed fish oil as the sole lipid source had higher glucose at 3 psu than at 30 psu. This study indicates that appropriate supplementation of dietary unsaturated and saturated fatty acids can improve shrimp osmoregulation capacity and thus promote shrimp growth and survival in low-salinity water.