Red drum Sciaenops ocellatus growth and expression of bile salt-dependent lipase in response to increasing dietary lipid supplementation

Authors: GONZÁLEZ-FÉLIX, MAYRA - Universidad De Sonora; GATLIN, DELBERT - Texas A&M University; PEREZ-VELAZQUEZ, MARTIN - Universidad De Sonora; WEBB, KEN - University Of Texas At Austin; GARCÍA-ORTEGA, ARMANDO - University Of Hawaii; Hume, Michael

Submitted to: Fish Physiology and Biochemistry Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2018
Publication Date: 10/1/2018
Citation: González-Félix, M.L., Gatlin, D.M., Perez-Velazquez, M., Webb, K., García-Ortega, A., Hume, M.E. 2018. Red drum Sciaenops ocellatus growth and expression of bile salt-dependent lipase in response to increasing dietary lipid supplementation. Fish Physiology and Biochemistry Journal. 44(5):1319-1331. https://doi.org/10.1007/s10695-018-0523-z.
DOI: https://doi.org/10.1007/s10695-018-0523-z

Interpretive Summary: The red drum fish has a relatively long history in aquaculture. The purpose of this study was to evaluate red drum growth and the lipase enzyme, a fat-digesting protein, production in response to increasing fish oil content in the diet. Four diets were formulated to provide either 3, 10, 16, or 23% fish oil. Young fish were stocked in an aquarium for 6 weeks. At the end of the study, fish fed the diet containing 3% fish oil were significantly smaller, had lower feed efficiency, and less whole-body fat than fish fed the other diets. These variables were not different among fish fed 10, 16, or 23% fish oil, although fish fed 10% fish oil showed the largest relative size and weight. More lipase enzyme was produced in fish fed 10% fish oil than in fish given the other fish oil treatments. No differences were found in the amounts of lipase produced among fish given the other fish oil levels, although fish fed 3% fish oil produced the lowest amount. Results from this study of providing fish oil in the diet could help ensure an ecologically sound and economically profitable production of red drum. This information is of interest to researchers and producers of red drum and other aquaculture fishes.

Technical Abstract: Sciaenops ocellatus has a relatively long history in aquaculture and many of the difficulties associated with its commercial culture have been addressed and successfully resolved; nevertheless, further research in lipid nutrition could address more comprehensive questions on the way these nutrients are utilized. Evidence points to the presence of a bile salt-dependent lipase in teleost fish, although a pancreatic lipase-colipase system has also been described in different species. The purpose of this study was to evaluate the red drum S. ocellatus growth and lipase mRNA expression in response to increasing dietary lipid supplementation. Four experimental diets were formulated to provide either 3, 10, 16, or 23% lipid using menhaden fish oil. Twenty juveniles with an overall mean initial weight of 2.3 g were stocked per aquaria in an experimental recirculating culture system; each diet was assigned to three aquaria and fed to fish for 6 weeks. At the end of the study, fish fed the diet containing 3% of dietary lipid were significantly (P < 0.0001) smaller and showed significantly lower feed efficiency, condition factor, hepatosomatic index, and intraperitoneal fat than fish fed the other diets. These variables showed no differences among fish fed 10, 16, or 23% lipid, although fish fed 10% lipid showed the largest size and weight. A straight broken-line regression model for thermal growth coefficient explained a substantial proportion of the variance, with an R**2 value of 0.9741. The break point estimate (R) corresponded to an estimated value of 9.4% of dietary lipid as the optimal inclusion level. Fish fed 16 and 23% lipid showed significantly higher (P < 0.0001) content of whole-body fat (4.61 and 4.30%, respectively), followed by fish fed 10% (3.13%) and 3% (0.94%). The native semi-purified bile salt-dependent lipase (BSDL) of red drum was 80.3 kDa. Relative BSDL expression evaluated in anterior intestine of red drum using the 2**-DeltaDeltaCT method, showed significantly higher (P = 0.0007) expression of the enzyme in fish fed 10% lipid, but no differences among the other dietary treatments, although fish fed 3% lipid had the lowest expression. Results provided in this study could help ensure an ecologically sound and economically profitable production of red drum by formulating diets that could improve its physiological performance, based on maximum mRNA expression of BSDL for the supplementation of dietary lipid.