Latitude™ oil is a transgenic canola oil that contains omega-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3). Previous research demonstrated that in rainbow trout diets, latitude oil is highly digestible (93%) and a potential candidate as a lipid replacement for diets formulated with fish oil and poultry fat. Given the success of previous research, this study evaluated the effects of high Latitude oil inclusion in trout feeds with the intent to replace fish oil in rainbow trout diets. Three isonitrogenous (50%), isolipidic (16%), and isocaloric (24 MJ/kg) diets that met or exceeded the published minimum requirements for rainbow trout were formulated. Diet 1 (FPO) consisted of a 7.84 % fish oil and 11.53% poultry fat blend, Diet 2 (LPO) contained 16% Latitude oil and 3.26% poultry fat blend, and Diet 3 (LO) consisted of 19.3% Latitude oil. Fish were initially stocked at 17g and were fed their respective diet for 47 weeks.
At the conclusion of the study, there was no significant differences between diets regarding condition factor, survival, feed conversion ratio, hepatosomatic index, visceral fat index and fillet yield. However, final weight, weight gain, and feed intake of fish fed LPO and LO were higher (P < 0.05) in comparison to fish fed the control (FPO). Histological analysis of the liver and distal intestine showed no significant morphological differences amongst treatments. Furthermore, LO inclusion reduced hepatic alanine transaminase, suggesting liver health was improved. Analysis of fillet fatty acid content resulted in no significant differences in total EPA + DHA (% FAME) as well as n-3 LC-PUFA (% FAME) amongst diets suggesting dietary docosapentaenoic acid (DPA) and EPA was converted into DHA and deposited into fillet. Overall, Latitude oil improved fish growth and fish health supporting its use as a potential omega-3 lipid source for rainbow trout feeds.