In conclusion, this study shows the possibility of replacement of
dietary FO by alternative lipid sources by considering the minimum requirements
of EFA in silvery-black porgy. Partial or total replacement of
dietary FO with T led to a decrease in growth performance, nutrient digestibility,
plasma hemolytic and antibacterial activities, which seemed
to indicate that this animal lipid source is not advisable for being used in
silvery-black porgy on-growing diets. Total replacement of the dietary
FO with SO led to an increase in whole body and fillet fat, lipid retention,
LA, n−6 PUFA and a decrease in protein retention and whole body
n−3/n−6 ratio. The inclusion of CO resulted in an increase in protein
retention and an improvement of the n−3/n−6 ratio without any negative
effect on growth performance and immune parameters. From the
above results, it is suggested that the vegetal oil sources are recommended
for total and partial replacement of FO in silvery-black porgy
diets, whereas tallow is not advisable as an alternative lipid source in
this species. Present findings need to be validated over a longer experimental
period that covers the entire on-growing phase under industrial
intensive rearing conditions.