determination on growth indices and immune responses of acipenser ruthenus juvenile fish fed by digestarom nutritional supplements

the sterlet (acipenser ruthenus) is one of the species of the exotic sturgeon (acipenseridae) family in iran. this important species produces caviar every year at the lowest cost and in the shortest time. the objective of this research was to assess the effect of digestarom, as a nutritional supplement, on the growth indices and safety factors of synthetically-cultured baby sterlets (acipenser ruthenus). this research was conducted in autumn 2013 on synthetically-cultured baby sterlets in a fisheries laboratory of the islamic azad university of rasht. the research plan was designed randomly with three treatment groups and one control group. the supplement under study was added to the basic diet of the samples in the following three dosages: 1, 1.5, and 2 gr/kg. a total of 72 juvenile sterlets with an average weight of 88.60 1.35 were divided into 6-member groups and were put in twelve 100-liter tubs. the samples were fed for 60 days manually based on 3% of their body weight. at the end of the aquiculture period, the study of some of the growth parameters of the samples revealed that the 1.5 gr dosing of digestarom (as a nutritional supplement) had a considerable effect and the results obtained from this dosing were significant different than the results of the control group. however, in the examination of safety factors it was found that the total immunoglobulin level, lysozyme (2 and 1.5 gr), and igm only increased considerably with 2-gr dosing of the supplement as compared to the control group samples. therefore, research results indicated that the growth and safety parameters were satisfactory with the 1.5 and 2 gr/kg dosages of the aforementioned nutritional supplement.