Incorporation of a Krill Protein Hydrolysate into the feeding regime of Atlantic cod (Gadus morhua) larvae - effect on growth and survival

Rowsell, Nicole Joy (2009) Incorporation of a Krill Protein Hydrolysate into the feeding regime of Atlantic cod (Gadus morhua) larvae - effect on growth and survival. Masters thesis, Memorial University of Newfoundland.

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Abstract

Atlantic cod (Gadus morhua) is being developed as a species for commercial scale aquaculture production. Years of study concerning the nutritional requirements of marine fish larvae have focused on the omega-3 (ω-3) fatty acid and lipid requirements, overshadowing the role and importance of protein and free amino acids in the larval diet. This study incorporated a Krill Protein Hydrolysate (Krill Protein) into a fatty acid/lipid-rich Artemia enrichment regime and examined the contribution that amino acids make to the growth and survival of Atlantic cod larvae. -- Atlantic cod larvae were fed Artemia enriched in AlgaMac 3010, DHA Selco and a Krill Protein Hydrolysate in eight different feeding regimes. The eight feeding treatments also included an unenriched Artemia treatment, and all were carried out in triplicate during the Artemia feeding stage (a 20 day period). -- During the Artemia enrichment, the Krill Protein Hydrolysate incorporated the highest proportion of phospholipid (25.5% total lipid), the most arachidonic acid (7.7% fatty acids) and DHA Selco and Krill Protein contributed similar proportions of total lipid (5.6%; 5.5%). Unenriched Artemia contained the highest concentrations of all free amino acids (FAA) studied. FAA incorporated by the Artemia enriched with Krill Protein and AlgaMac 3010, respectively, expressed as a percent of FAA concentrations in unenriched Artemia were: alanine (54% of unenriched; 50% of unenriched), leucine (39%; 66%), serine (44%; 56%), isoleucine (40%; 67%), lysine (32%; 59%), and valine (44%; 62%). -- Growth during the experiment, measured as total length (mm), was significantly improved in the larvae fed DHA Selco/Krill Protein enriched Artemia on alternating days (P=0.010). The DHA Selco/Krill Protein treatment produced the best specific growth rate (2.55), in fact, all treatments containing Krill Protein produced significantly higher SGRs than that found in the unenriched treatment (P<0.05). Alanine, leucine, serine, isoleucine, lysine and valine concentrations, measured as mole %, were significantly higher in larvae fed Artemia enriched with AlgaMac 3010/Krill Protein and those fed DHA Selco/Krill Protein than the FAA levels in the unenriched treatment. Further, larvae fed solely AlgaMac 3010 enriched Artemia had significantly higher levels of alanine than larvae fed unenriched Artemia. Artemia enriched in DHA Selco and the Krill Protein Hydrolysate contained high concentrations of total lipid (TL), total fatty acids (TFA) and triacylglycerol (TAG). -- These nutritional components probably contributed to the increased growth rates found in larvae fed DHA Selco/Krill Protein enriched Artemia on alternating days. Artemia enriched in AlgaMac 3010 contained higher levels of phospholipid than all other treatments, possibly contributing to the significantly improved survival rate in the larvae fed AlgaMac 3010/Krill protein enriched Artemia in combination (44%) as opposed to those fed Krill Protein enriched Artemia alone. -- A suggested Artemia diet feeding regime for Atlantic cod larvae using DHA Selco (lipid), AlgaMac 3010 (lipid) and a Krill Protein Hydrolysate (protein) in a 1:1 (lipid:protein) ratio would be: Day 1 - AlgaMac 3010 enriched Artemia, Day 2 - Krill Protein enriched Artemia, Day 3 - DHA Selco enriched Artemia, Day 4 - Krill Protein enriched Artemia, and continue to repeat this cycle.

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