The nutritional effectiveness of a protein source depends on its digestibility, its amino acid profile and the size of its peptides. All these characteristics significantly influence protein synthesis and growth in fast growing shrimp larvae and postlarvae. Diets based on fish or squid meals tend to give good results but can be improved considerably through the inclusion of addition al essential amino acids and di- and tripeptides. To have a better understanding of the fundamental and zootechnic aspect of protein nutrition and protein quality, three studies with white shrimp Litopenaeus vannamei were conducted by INVE Aquaculture in co-operation with several academic institutions.
Amino acids – The first study applied a two-level fractional factorial Plackett-Burman design to identify the most important amino acids (variables) affecting growth of shrimp larvae and postlarvae. It allowed screening 20 amino acids in one single trial with 110 larval rearing tanks (22 treatments and 5 replicates). Those amino acids that had a statistically significant positive effect on growth were then added to a new experimental diet and a second shrimp hatchery test validated the usefulness of this approach.
Peptides – Th is study enabled profiling of different protein sources based on the molecular weight size distribution of the peptides with size-exclusion chromatography . Enriching feeds with the right combination of amino acids and small/ medium-sized proteins helps avoid imbalances that can occur with free amino acids which may be absorbed too quickly or inefficiently , or with large proteins that need complete enzymatic breakdown .
Digestibility – The third study is a newly-developed in vitro assay with enzyme extracts of shrimp larvae and postlarvae that was used to screen (novel) protein sources for digestibility in zoea, mysis and PL stages.
The information obtained from this extensive research on protein quality has been employed to improve INVE’s ingredient sourcing and feed formulation. This approach had a proven effect on growth and robustness of shrimp as demonstrated in many commercial hatchery trials with INVE’s top feed range.