Effects of Canola and Safflower Oil Supplementation in Diets, on Growth Performance and Fatty Acid Composition of Russian Sturgeon (Acipenser gueldenstaedtii Brandt, 1833)

The aim of this study was to determine the impact on growth performance and muscle fatty acid composition, of replacement of 50% fish oil (FO) with canola oil (CO) and safflower oil (SFO) in the diets of Russian sturgeon (Acipenser gueldenstaedtii). Two isoproteic (48%) and isolipidic (12%) diets were formulated combining two oil sources (50% fish oil + 50% canola oil or 50% fish oil + 50% safflower oil). The diets were fed to apparent satiation to triplicate groups for 15 weeks, twice a day. No significant differences were observed between the experimental groups fed CO and SFO diets in terms of weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. The experimental groups fed CO and SFO diets did not show significant differences in terms of protein, lipid, ash, and moisture content in their muscle. There were no significant differences in muscle between total n-3 fatty acids but total n-6 fatty acids were significantly higher in SFO group (24.90%) than in CO group (21.30%). Total n-6 fatty acids were also higher than (20.43%) at the start. In conclusion, 50% replacement of FO by CO or SFO in Russian sturgeon diets had no negative effect on growth performance, feed efficiency and fatty acid composition in the muscle of this species

Genetic Inactivation of European Sea Bass (Dicentrarchus labrax L.) Eggs Using UV-Irradiation: Observations and Perspectives

International audienceAndrogenesis is a form of uniparental reproduction leading to progenies inheriting only the paternal set of chromosomes. Ithas been achieved with variable success in a number of freshwater species and can be attained by artificial fertilization ofgenetically inactivated eggs following exposure to gamma (c), X-ray or UV irradiation (haploid androgenesis) and byrestoration of diploidy by suppression of mitosis using a pressure or thermal shock. The conditions for the geneticinactivation of the maternal genome in the European sea bass (Dicentrarchus labraxL.) were explored using differentcombinations of UV irradiation levels and durations. UV treatments significantly affected embryo survival and generated awide range of developmental abnormalities. Despite the wide range of UV doses tested (from 7.2 to 720 mJ.cm22), only onedose (60 mJ.cm22.min21with 1 min irradiation) resulted in a small percentage (14%) of haploid larvae at hatching in theinitial trials as verified by flow cytometry. Microsatellite marker analyses of three further batches of larvae produced by usingthis UV treatment showed a majority of larvae with variable levels of paternal and maternal contributions and only one larvadisplaying pure paternal inheritance. The results are discussed also in the context of an assessment of the UV-absorbancecharacteristics of egg extracts in this species that revealed the presence of gadusol, a compound structurally related tomycosporine-like amino acids (MAAs) with known UV-screening properties