INCREASE OF THE DIETARY N-3 N-6 FATTY-ACID RATIO AND ADDITION OF PHOSPHORUS IMPROVES LIVER HISTOLOGICAL ALTERATIONS INDUCED BY FEEDING DIETS CONTAINING SOYBEAN-MEAL TO GILTHEAD SEABREAM, SPARUS-AURATA/

In a previous study, several histological alterations were found in th e liver of gilthead seabream fed with a diet containing 30% soybean me al (SBM). In the current study, SBM containing diets were supplemented with either potassium phosphate, zinc sulfate or phytase( Aspergillus ficuum), or increasing the dietary n - 3/n - 6 fatty acids ratio to m eet that of a fish meal based diet. Diet composition did not affect fi sh growth, feed efficiency (FE) or protein productive value (PER). Pho sphorous supplementation significantly reduced hepatosomatic indexes ( HSI), although it did not alter liver lipid content. Both phosphorous supplementation and correcting the dietary n - 3/n - 6 fatty acid rati o significantly altered the lipid and protein content in fish muscle, Only these two treatments and principally the corrected dietary n - 3/ n - 6 fatty acid ratio, improved the liver histological alterations ob served in fish fed with SBM based diets. (C) 1998 Elsevier Science B.V .