Influence of fish meal quality and feed pellet on growth, feed efficiency and muscle composition in gilthead seabream ( sparus aurata)

Abstract

The effect of fish meal quality on growth, feed efficiency, protein digestibility and fillet composition was studied in a growth experiment with gilthead seabream. The experiment included a comparison of pelleted feed with extruded feed. The fish were fed three extruded diets which varied in the quality of the fish meal used in the respective feeds: low quality fish meal, good quality fish meal, and a mixture (50%) of the two fish meal qualities. Fish meal quality was judged by protein digestibility as measured with mink as the test animal and by the content of biogenic amines. A fourth experimental group was fed a pelleted feed with the same mixed fish meal blend. The experiment started with 70 g seabream and lasted for 3 months until the fish reached about 160 g. All groups showed good growth and feed efficiency during the experimental period, with daily specific growth rates (SGR) of 0.90–1.00% and feed efficiencies (FE; fish weight gain per feed offered) from 0.58 to 0.66. The fish fed the feed with low quality fish meal showed significantly poorer feed efficiency than the other groups, and there was a significant correlation between feed efficiency obtained in seabream and the protein digestibility as measured with mink. No difference was observed among groups fed the extruded diets, for growth, fillet composition or amount of liver or viscera, although a significant correlation was obtained between SGR and protein digestibility in mink. Fillet lipid content was higher in fish fed the extruded feed, compared with those fed the corresponding pelleted diet. Protein digestibilty in seabream showed no difference among the extruded feeds, while the pelleted feed was significantly lower.