The influence of dietary fish oil replacement with mixture of vegetable oils on reproductive performance, immune responses and dynamic of fatty acids during embryogenesis in Oncorhynchus mykiss

Abstract

A 90-day feeding trial was carried out to examine the influence of fish oil (FO) substitution with blends of vegetable oils (VOs) on reproductive efficiency of female brooders and fluctuation in fatty acid (FA) profile of embryos in Oncorhynchus mykiss. A basal diet was formulated in which 20% (80FO/20VO), 50% (50FO/50VO), 75% (25FO/75VO) and 100% (100VO) of FO were replaced by mixture of VO. Reproductive performance of brooders was not affected by drastic alternations in FA profile of diets. The level of saturated and monounsaturated FAs (MUFAs) significantly increased, whereas the levels of long-chain polyunsaturated FAs (LC-PUFAs), mainly docosahexaenoic acid, profoundly decreased during embryogenesis. The concentrations of MUFA and n−6 PUFA increased in the eggs with increasing the incorporation of VO mixture in diets; however, the concentration of LC-PUFA and n−3/n−6 PUFA ratio decreased. Haematological parameters and humoral immune responses including total immunoglobulin content, lysozyme and alternative complement pathway activities in brooders fed with the experimental diets did not statically different. In summary, incorporating mixture of various VO sources especially linseed and sunflower oils as good sources of α-linolenic and linoleic acids, respectively, along with low levels of residual fat from fish meal in diet suggested a good strategy for providing the appropriate essential FA requirements of O. mykiss brooders for their successful reproduction.