Effects of different dietary oils on egg quality and reproductive performance in rainbow trout Oncorhynchus mykiss

The study was conducted to evaluate effects of different dietary oils on egg quality and reproductive performance in rainbow trout. Broodfish ( approximate to 870 g) were fed four iso-nitrogenous and iso-lipidic diets differing in lipid sources: fish oil (FO), linseed oil (LO) and sesame oil (SO) as well as a commercial trout diet (CD) for about 5 months prior to spawning. Growth performance did not differ among the trout in the treatment groups. Mean diameter, volume and weight of eggs did not differ among the dietary treatments. Absolute fecundity, relative fecundity and gonadosomatic index were not affected by dietary treatment. A sub-set of eggs from females fed the experimental diets were fertilized to assess the reproductive performance of broodfish. When diets were fed, devoid of fish oil, fertilization rates were 89.2 +/- 5.8 and 92.1 +/- 4.9 %, eyeing rates were 87.3 +/- 5.3 and 84.1 +/- 4.4 % and hatching rates were 81.2 +/- 4.3 and 78.3 +/- 3.4 % in LO and SO fed fish, respectively. Fatty acid content of the eggs from broodstocks with a different nutritional history was affected by the dietary lipid sources. Eicosapentaenoic acid (EPA), arachidonic acid (ARA), and docosahexaenoic acid (DHA) concentrations in females fed vegetable oil based diets were greater than the dietary concentrations. Overall, results from the present study indicate there can be inclusion of LO or SO as dietary lipid sources without compromising egg quality and reproductive performance. Furthermore, there is efficient bioconversion of 18C fatty acids to 20-22 C fatty acids in rainbow trout.