Proceeding of Veterinary and Animal Science Days 2018, 6th- 8th June, Milan, Italy HAF © 2013 Vol. V, No. 1s ISSN: 2283-3927 l Sturgeons, as well as paddlefishes, belong to the Acipenseriformes group, which is one of the most primordial 57 orders of the Osteichthyes that comprehends 25 species spread throughout Europe, Asia and North America (Birnstein, 1993). The present study aims at investigating muscle growth and development as well as fatty acid profile in Siberian sturgeon free-embryos when subjected to three different rearing densities. Fatty acids, in particular polyunsaturated fatty acids of n-3 series, are generally known as key nutrients in fish larvae. This study was approved by the Ethic Committee of the University of Milan (OPBA_22_2017). Siberian sturgeon larvae were reared at 18°C, at three stocking densities until complete yolk-sac absorption: low (LD, 30 larvae/l), mid (MD, 80 larvae/l) and high (HD, 150 larvae/l). Sampling timepoints were: hatching, schooling and complete yolk-sac absorption stage (YSA). Sacrificed larvae were weighed and histological analyses were performed in order to assess muscle development as described elsewhere (Di Giancamillo et al. 2015; Aidos, et al., 2017); fatty acid profile was determined by GC-FID analysis as described by Vasconi et al. (2015). Statistical analysis was performed with SAS software (v. 9.3, Cary Inc., NC). At the end of the experiment, LD larvae presented a higher weight than larvae reared at the other two densities (P<0.05). Within the schooling stage (Fig. 1), Total Muscle Area was lower for HD larvae (P<0.05); red and white muscle areas in schooling and YSA were higher than at hatching (P<0.05), regardless the density. Concerning fatty acids, no statistical differences were recorded between different rearing densities, while during the development regardless the rearing density, there was a common pattern: linoleic and alfa linolenic acids, significantly decreased their relative Keywords Siberian stugeon, Larvae, Growth, Muscle development, Stress, Density. CORRESPONDING AUTHOR Alessia Di Giancamillo alessia.digiancamillo@unimi.it JOURNAL HOME PAGE riviste.unimi.it/index.php/haf Effect of different stocking densities on growth, muscle development and fatty acid profile of Acipenser baerii larvae. L. Aidos1, M. Vasconi1, M.Lanfranchi2, A. Di Giancamillo1,* 1 Department of Health, Animal Science and Food Safety, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy. 2 Società Naviglio Agricola SS, Goito, Italy. http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en Proceeding of Veterinary and Animal Science Days 2018, 6th- 8th June, Milan, Italy 84 HAF © 2013 Vol. V, No. 1s ISSN: 2283-3927 content, while others, as arachidonic acid and DHA, significantly increased. Siberian sturgeon larvae reared at LD or MD reveal an anatomically normal muscle development, while in the HD it is possible to observe a slowdown. What the aquaculture industry requires is a set of guidelines that allows the development of a sustainable industry, so that we tried to develop guidelines for stocking density in the very early stage of farming. As a conclusion, it would seem that mid density could be more suitable for this species in this stage of development. Acknowledgments: The authors wish to thank the sturgeon farm “Società Naviglio Agricola” for the supply of the fertilized eggs utilized for this study. References Aidos L., Valente L.M.P., Sousa V., Lanfranchi M., Domeneghini C., Giancamillo A.D., 2017. Effects of different rearing temperatures on muscle development and stress response in the early larval stages of Acipenser baerii.European Journal of Histochemistry 61,(4),2850. doi:10.4081/ejh.2017.2850. Birnstein, V. J.,1993. Sturgeon and paddlefishes: threatened fishes in need of conservation. Conservation 298 Biology 7, 773–787. Di Giancamillo A., Rossi R., Pastorelli G., Deponti D., Carollo V., Casamassima D., et al. 2015. The effects of dietary verbascoside on blood and liver oxidative stress status induced by a high n-6 polyunsaturated fatty acids diet in piglets. Journal of Animal Science 93, 2849-59. Vasconi, M., Caprino, F., Bellagamba, F., Busetto, M. L., Bernardi, C., Puzzi, C. and Moretti, V. M. 2015. Fatty Acid Composition of Freshwater Wild Fish in Subalpine Lakes: A Comparative Study. Lipids, 50: 283-302. doi:10.1007/s11745-014-3978- Figure 1: Siberian sturgeon larva in the schooling stage http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en