LatitudeTM Oil as a Sustainable Alternative to Dietary Fish Oil in Rainbow Trout (Oncorhynchus mykiss): Effects on Filet Fatty Acid Profiles, Intestinal Histology, and Plasma Biochemistry

Abstract

The aim of this study was to evaluate the effects of Latitude™ oil (transgenic canola) fed to rainbow trout, Oncorhynchus mykiss, for 52 weeks on growth performance, non-specific immune responses, histology, and filet omega-3 fatty acid content. Latitude™ oil (LO) has high lipid digestibility (93%), and contains omega-3 fatty acids eicosapentaenoic acid (EPA, C20:5n-3), docosapentaenoic acid (DPA, C22:5n-3), and docosahexaenoic acid (DHA, C22:6n-3). Three isonitrogenous (49%), isolipidic (20%) and isocaloric (24.2 MJ kg−1) diets differing by lipid source (0, 8, or 16% LO, replacing fish oil and poultry fat) were fed over an entire production cycle beginning with 19 g juvenile fish. At the end of the 52-week feeding trial, final body weight, weight gain and specific growth rate of fish fed 8% LO (LO-8) and 16% LO (LO-16) diets were significantly higher than those fed the 0% LO (LO-0) diet (P < 0.05). Phagocytic respiratory burst in fish fed the LO-16 diet was significantly higher than those fish fed the other 2 diets (P < 0.05). There were no differences in superoxide dismutase, catalase and lysozyme. Histological examination of the distal intestine indicated reduced inflammation in fish fed the LO-8 diet but not the LO-0 and LO-16 diets. Filet DHA content of fish fed the LO-8 and LO-16 diets were similar to those of fish fed the LO-0 diet. As these diets had lower DHA content, this suggests dietary EPA and DPA from LO was converted to DHA and deposited in the filet. This is supported by increased expression of genes involved in fatty acid elongation, desaturation and beta oxidation in both liver and muscle of fish fed LO (P < 0.05). Total EPA+DHA content of the edible filet ranged between 1,079–1,241 mg 100 g−1 across treatments, each providing the recommended daily intake for human consumption (500–1,000 mg day−1). Overall, this study demonstrated that LO fed over an entire production period is a highly digestible lipid source suitable and sustainable for meeting the fatty acid requirements of rainbow trout, as well as consumer expectations for filet omega-3 fatty acid content.

Utilization of functional feed additives to produce cost‐effective, ecofriendly aquafeeds high in plant‐based ingredients

“…Furthermore, total n‐3 LC‐PUFA content of terrestrial oil blend‐fed fish fillets also meets the recommended dietary consumption level of total n‐3 LC‐PUFA for heart health and human well‐being, albeit in small fish. In another recent, study, Hong et al 217 showed that Latitude™ oil inclusion at 8% or 16%, substituting FO and poultry fat improves fish growth, yields higher filet n‐3 LC‐PUFA content, and creates a viable source of lipid in the diets of rainbow trout. All the above research findings substantiate that the novel sources of EPA and DHA have the potential to increase n‐3 LC‐PUFA levels in salmonids and other farmed fish species with no major adverse effects on their growth, feed utilization efficiency, and health performance.…”

Engineering plant-based feedstocks for sustainable aquaculture

“…In addition to the benefits that the use of these oils can have for consumers, the use of vegetable oils rich in omega-3 LC-PUFA can also have added benefits for the fish such as reduced liver fat infiltration and hepatocyte area relative to fish fed feeds containing wildtype Camelina [35]. Perhaps, most importantly to note is that none of the trials performed to date have reported any adverse effect in fish fed these novel oils thus demonstrating the potential for the exploitation of this key raw material [27][28][29][30][31][32][33][34][35][36].…”

Evaluation of long-chain omega-3 canola oil on Atlantic salmon growth, performance, and essential fatty acid tissue accretion across the life cycle: a review

“…7%), has a considerably higher ω6:ω3 ratio than ω3 canola oil. Evaluation of Latitude alone or in combination with other oils in feed formulations for farmed shrimp (Litopenaeus vannamei; Gia Vo et al, 2021) and rainbow trout (Oncorhynchus mykiss; Hossain et al 2021, Hong et al 2022 suggests that this oil supports shrimp and salmonid growth with no harmful effects.…”