The influence of different ratios of saturated and monounsaturated fatty acids on growth performance and lipid metabolism of Rachycentron canadum juveniles

Author(s)

Victor Hugo Marques Lorenti

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2021-12-14

Examining board members

Renata Guimarães Moreira Whitton; Rafael Tsuyoshi Inoe Coelho; Cristiéle da Silva Ribeiro; Neuza Sumiko Takahashi

• Advisor: Renata Guimarães Moreira Whitton; Bruno Cavalheiro Araujo

Abstract

The use of fish oil (FO) in marine aquaculture is important because of the presence of long chain and highly unsaturated fatty acids (LC-PUFA) of the n3 series. However, production of FO is limited and for this reason alternative sources of lower cost and more stable production as vegetable oils (VO) have been investigated. However, this substitution in most cases negatively impacts the growth and changes the lipid metabolism of the animals, mainly due to the presence of high amounts of saturated (SFA) and monounsaturated (MUFA) fatty acids (FA) and absence of LC-PUFAs in VO. An alternative to producing low-cost diets that meet the nutritional needs of fish is the use of VO supplemented with LC-PUFA. However, studies with marine fish showed that diets with high amounts of SFA and MUFA alter lipid deposition in the liver and the expression of genes related to the synthesis and oxidation of FA. The objective of the present project is to investigate the influence of alternative lipid sources rich in SFA and MUFA supplemented with LC-PUFA on growth and lipid metabolism of Rachycentron canadum juveniles. An 8-week feeding trial was carried out using four isoproteic and isolipidic diets as follows: FO-D (fish oil, as control diet), SFA-D (rich in SFA), MIX-D (same levels of SFA and MUFA), and MUFA-D (rich in MUFA). Experimental diets were supplemented with arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (3, 5, and 10 g kg1, respectively). The growth performance, fatty acid (FA) profile of liver and muscle, hepatocyte morphology, and gene expression related to the FA synthesis and oxidation on the liver were examined. In general, production performance was not impaired in fish-fed FO-free diets, supporting the hypothesis that alternative lipid sources could be used in cobia\'s aquafeed formulations when the LCPUFA are adequately supplemented. High dietary SFA levels were disproportionally deposited the liver and muscle. Contrariwise MUFA was mainly deposited in the liver and muscle, reflecting the dietary inclusion levels. The main FA influencing this pattern were 12:0 and 18:1n-9. The expression of fatty acid synthase (fas) was up-regulated in the FO-D group compared to SFA-D and MIX-D groups. There were no differences in the relative expressions of carnitine palmitoyltransferase 1 (cpt-1) and lipase lipoprotein (lpl). The liver morphology results indicated that fish-fed SFA-D presented a smaller lipid vacuoles area than those fed other experimental diets. This study shows that SFA with shorter carbon chains such as 12:0 can be administered in cobia aquafeeds to stimulate these molecules\' catabolism, providing energy for growth, and retaining LC-PUFAs in tissues, especially in the muscle, exhibiting a healthier fillet for consumers. (AU)

• FAPESP's process: 19/09246-9 - The influence of alternative sources of saturated and monounsaturated fatty acids, suplemented with LC-PUFA in growth and lipid metabolism of Rachycentron canadum juveniles (Teleostei: Perciformes)
• Grantee: Victor Hugo Marques Lorenti
• Support Opportunities: Scholarships in Brazil - Master