Protein Sparing Effect of Lipids in Diets for Fingerlings of Gilthead Sea Bream

Abstract

A feeding trial was conducted to determine the sparing effect of lipids on dietary protein in gilthead sea bream Sparus aurata fingerlings, by combining different levels of protein (42-58%) at two lipid levels (9, 15%) in the diets. Sardine meal and sardine oil were employed as the main source of dietary protein and lipid, respectively. Weight gain and specific growth rate of fish improved for each dietary protein level when lipids were increased in diets from 9% to 15%, up to 52% dietary protein. There was evidence of a protein sparing effect of dietary lipid, as evident by a reduction of dietary protein from 52 to 46%, and an increase of dietary lipid from 9 to 15% in diets resulting in slightly better fish growth. There were no significant effects on the protein efficiency ratio. The increase of dietary lipid produced an increase in body lipid deposition, both in visceral and non-visceral tissues.