Spirulina as a nutrient source in diets for growing sturgeon (Acipenser baeri ) Giovanni B Palmegiano 1 , Elisabetta Agradi 2 , Gilberto Forneris 3 , Francesco Gai 1 , Laura Gasco 4 , Elisabetta Rigamonti 2 , Benedetto Sicuro 3 & Ivo Zoccarato 4 1 CNR Institute of Science of Food Production,Torino Division, Grugliasco (TO), Italy 2 Department of Pharmacological Sciences, University of Milano, Milano, Italy 3 Department of Animal Production, Grugliasco (TO), Italy 4 Department of Animal Husbandry Sciences, Grugliasco (TO), Italy Correspondence: G B Palmegiano, CNR Institute of Science of Food Production,Torino Division,Via L. daVinci 44, Grugliasco (TO), Italy. E-mail: giovanni.palmegiano@ispa.cnr.it Abstract The e⁄ciency of diets with the inclusion of Spirulina for Siberian sturgeon weaning has been tested. Three isoproteic and isoenergetic diets were formulated with an increasing level of Indian strain Spirulina (SP 40%, SP 50% and SP 60%); the diets were tested against a control diet without microalgae. The results show that Spirulina inclusion improves growth and that an inclusion level of 50% gave the greatest growth rate, a better favourable feed conversion rate and the highest protein e⁄ciency. The fatty acid com- position of ¢llets showed di¡erences between the experimental and control diets: an increase in the Spirulina level induces increases in palmitic and li- noleic acids and a decrease in the myristic acid. The control diet was characterized by high levels of eico- sapentaenoic and docosahexaenoic acids. At the end of the experiment, statistical di¡erences appeared in the fatty acid pro¢le of the sturgeon ¢llet, mainly con- cerning high content of monounsaturated fatty acid and polyunsaturated fatty acid in the sturgeon ¢llets. If the problems related to the high production costs are solved, Spirulina could prove a good partial sub- stitute ¢sh meal. Keywords: Spirulina, sturgeon, productive traits, fatty acids Introduction Diets in aquaculture are based on conventional feed- stu¡s such as ¢sh oil and ¢sh meal, but these are very expensive. The future development of aquaculture will be greatly constrained by the availability of an alternative source of feed ingredients. The proportion of global ¢sh meal production used in ¢sh feeds has increased from10% to 35% over the last15 years. Pre- dictions of ¢sh meal requirements for the future are approximately 44% of the 10-year average global ¢sh meal production (Naylor, Goldberg, Primavera, Kautsky, Beveridge, Clay, Folke, Lubchenco, Mooney & Troell 2000). A large number of studies have been carried out on use of plant protein sources in ¢sh feeding. Gomes, Rema and Kaushik (1995) have evaluated the e⁄- ciency of the substitution of ¢sh meal protein with soybean meal on the performances and body compo- sition in rainbow trout and sturgeon. Di¡erent plant protein sources have been evaluated on di¡erent freshwater ¢sh (Gouveia & Davies 1999; Borlongan, Eusebio & Welsh 2002; Davies, Gouveia & Tekinay 2002). Sturgeon has mainly been farmed for caviar production but in the last decade there has been in- creased interest in farming for £esh production. Be- cause of the need to expand production by introducing new species, sturgeon farming has seen an increase. In Italy, which is the largest EU sturgeon producing country, production has increased from 280 t year 1 , in the 1980s, to the present 500 t year 1 (Guarda, Bertoja, Zoccarato, Tartari & Biolatti 1997). There have been few studies on stur- geon feeding and nutrition, but they often do not con- cern ¢sh meal and ¢sh oil substitution. Gisbert and Williot (2002) reported a fully detailed review on Si- berian sturgeon larval rearing. Papers on Siberian sturgeon feeding have been written by Dabrowski, Kaushik and Fauconneau (1985) and later by Me¤ dale, Aquaculture Research, 2005, 36, 188^195 doi: 10.1111/j.1365-2109.2005.01209.x 188 r 2005 Blackwell Publishing Ltd