Aquaculture industry is facing many evolving sustainability challenges. Improving feeding protocols and fish digestive efficiency will help the sector to attain a higher productivity, concomitant with a lower environmental impact. Therefore, discovering new methods to improve gastrointestinal maturation alongside with higher digestive efficiency at early stages without compromising survival and fitness represents a very promising avenue in fish nutrition research. Nutritional programming refers to a nutritional intervention during the early phases of development that will imprint an individual physiological memory resulting in long-term effects on growth and physiological function. Since digestive capacity is key to resilience of fish populations, applying this novel concept to the fish production provides numerous possibilities for improving adaptive responses to fish to challenging conditions.
Nutritional research has demonstrated that dietary protein and amino acids (AA) a play fundamental role in the overall fish digestive capacity and consequently growth performance. The objective of this work was to assess in ovo AA supplementation as long-term modulator of larval intestinal maturation and metabolic capacity at optimum (28ºC) and challenging temperature (32ºC). The AA supplementation was performed at zebrafish embryonic stage, using the sonophoresis technique. The experimental setup was, control (CTRL, no supplementation), amino acid glutamine (GLN) or arginine (ARG) supplementation. The experiment lasted until 40 days post-fertilization. Growth performance and digestive and metabolic enzymes activities were analysed to evaluate the larval nutrition-induced metabolic plasticity and the effects on fish resilience to challenging conditions.
The preliminary results showed that fish survival was not affected either by the sonophoresis technique or rearing temperature (p>0.05). Growth performance was affected by both, temperature and AA treatment. Overall, 28ºC-fish showed higher final dry weight (DW) than 32ºC-fish, reaching the maximum DW in fish supplemented with glutamine and reared at 28ºC. On the other hand, arginine supplementation statistically improved DW at 32ºC, suggesting a better metabolic adaptation to cope with higher temperatures. This study shows that sonophoresis is a good technique to incorporate amino acids in fish eggs. Amino acid supplementation at embryonic stage was able to promote fish performance at later developmental stage and, specifically, results suggest that in ovo arginine supplementation might improve fish resilience to challenging conditions.
Acknowledgments: The present study was supported by projects ALG-01-0145-FEDER-029151 “PROLAR – Early metabolic programming in fish through nutritional modulation”, and UID/Multi/04326/2019 financed by the FCT (Portugal). Sofia Engrola acknowledge a FCT investigator grant (IF/00482/2014/CP1217/CT0005) funded by the European Social Fund, the Operational Programme Human Potential and FCT.