Zootechnical performance, biochemical composition and gene expression of digestive enzymes in Litopenaeus vannamei post‐larvae fed the nematode Panagrolaimus sp. ( NFS 24–5)

Abstract

This study investigated the effect of different size ranges, densities and feeding frequencies of the nematode Panagrolaimus sp. strain NFS 24–5 on zootechnical performance, biochemical composition and digestive enzyme gene expression of Litopenaeus vannamei stage 1 (PL1) post-larvae. Trial 1 supplied large (LN) (800–1,200 μm) or small (SN) (200–800 μm) DHA-enriched nematodes twice daily, substituting non-enriched Artemia (control treatment) totally (100%) or partially (75%). Trial 2 only supplied LN once or thrice daily, replacing Artemia at 100% or 75%. Trial 1 larvae fed on LN (100LN and 75LN) showed similar zootechnical performance and biochemical composition to those reared with Artemia (100A). Supplying 100% SN negatively affected PL1 total length. LN contained twofold more arachidonic (ARA) and eicosapentaenoic acids than SN, and docosahexaenoic acid (DHA) was fivefold higher. Trial 2 obtained better zootechnical results with 75% Artemia substitution than 100%. Shrimp fatty acid profiles were similar in Trials 1 and 2. Post-larvae fed 100LN had twofold higher percentages of ARA and DHA compared with those from the control treatment. Amylase, lipase and chymotrypsin genes were over-expressed in PL1 fed 100LN once daily. Contrarily, amylase and trypsin genes were under-expressed in PL1 fed 100LN or 75LN thrice daily, evidencing a better nematode availability for shrimp. In conclusion, non-enriched Artemia can be partially or totally substituted by large DHA-enriched Panagrolaimus sp. during the larval stage of L. vannamei when the nematode is distributed twice daily.