<i>Nannochloropsis oceania</i>-derived defatted meal as an alternative to fishmeal in Atlantic salmon feeds

<div><p>Defatted microalgal biomass derived from biorefinery can be potential feed ingredients for carnivorous fish. The present study investigated the growth, feed intake:gain and health parameters in Atlantic salmon fed for 84 days with defatted <i>Nannochloropsis oceania</i> as a fishmeal replacer. Fish fed feeds containing the algal biomass (at 10 and 20% inclusion, alga groups) were compared with groups that consumed alga-devoid feeds (control group). The fish that received 20% alga tended to have reduced weight gain and specific growth rate. Condition factor, feed conversion ratio and feed intake of this fish group were significantly different when compared with the control group. Hepatosomatic and viscerosomatic indices, whole body and fillet proximate composition were not affected by the dietary treatments. Digestibility of dry matter, protein, lipid, ash and energy, as well as retention of lipid and energy of the fish that received feed with 20% alga meal were also significantly different from those of the control group. Serum superoxide dismutase activity of the 10% alga-fed fish was significantly higher compared with the control fish. Although alga feeding did not cause any distal intestinal inflammation, the intestinal proteins that were altered upon feeding 20% algal meal might be pointing to systemic physiological disturbances. In conclusion, feeds with 20% alga had a negative effect on feed intake, FCR, lipid and energy retention and health of the fish. The defatted <i>Nannochloropsis oceania</i> can be used at modest inclusion levels, around 10%, without negative effects on the performance of Atlantic salmon.</p></div

Tetraselmis suecica and Tisochrysis lutea meal as dietary ingredients for gilthead sea bream (Sparus aurata L.) fry.

In the present study, the nutritional value of Tetraselmis suecica and Tisochrysis lutea (previously known as Isochrysis aff galbana T-ISO strain) freeze-dried biomass for feeding Sparus aurata fry was evaluated. A total of 25,500 fry (3.7 mg body weight) were fed for 55 days on diets containing 5 and 10%(w/w) Tetraselmis or Tisochrysis, as well as on a microalgae-free diet. Fish fed 5 % Tetraselmis showed higher growth performance, nutrient utilization, and survival values than fish fed Tisochrysis. The use of microalgae significantly decreased the body lipid content in fry fed the highest microalgae level. Fry fed Tisochrysis-supplemented diets increased the DHA content in muscle, and consequently the EPA/DHA ratio decreased significantly, whatever dietary level considered. In general, digestive protease activities were not adversely affected by dietary microalgae inclusion, although slight variations were observed during fish development. Microalgae utilization causes a positive effect on intestinal mucosa ultrastructure owing to an increase of total enterocyte absorption surface that was observed in fish fed microalgae-supplemented diets. Cluster analysis of data separated clearly fish fed Tisochrysis-supplemented diets from the rest of experimental groups. This study confirms that Tetraselmis freeze-dried biomass can be used as dietary ingredient in started feeds for S. aurata fry, although an inclusion level of 5 % is recommended.Versión del editor2,326