五种养殖鲟、鳇鱼DNA含量的比较

采用德国Partec Pas Ⅲ型流式细胞仪,以鸡红细胞为标准DNA(含量为2.3pg/N),测定了俄罗斯鲟(Acipenser gueldenstaedti Brandt)、西伯利亚鲟(Acipenser baerii Brandt)、史氏鲟(Acipenser schrencki Brandt)、小体鲟(Acipenser ruthenus Linnaeus)和达氏鳇(Huso dauricus Ceorgi)的体细胞DNA含量。结果表明,在上述五种鲟鱼类的DNA含量中,俄罗斯鲟、西伯利亚鲟和史氏鲟的DNA含量非常接近,分别为12.24pg/N,11.60ps/N,11.59pg/N,三种鲟鱼相比较差异并不显著。小体鲟和达氏鳇的DNA含量是6.06pg/N和4.77pg/N,两种鱼相比较差异也不显著。但与上述三种鲟鱼相比较DNA含量几乎相差1倍。从测定的结果并结合已发表的有关鲟鱼类资料可以确定俄罗斯鲟,西伯利亚鲟和史氏鲟属于八倍体类型,而小体鲟和达氏鳇则属于四倍体类型。     

达氏鳇人工繁殖及其与史氏鲟杂交的初步研究

对达氏鳇繁殖生物学作了分析，认为卵巢重量随体重的增大而增大。成熟卵子呈黑色，卵外膜色泽光亮，而未成熟卵子为灰黑斑色，卵外膜色泽暗淡。其怀卵量明显小于史氏鲟，而卵粒重却大于史氏鲟。人工催情利用抗低温催情剂类固醇激素17a-羟基-20β双羟孕酮诱导达氏鳇排卵，排精，并与史氏鲟进行了正反杂交，获得产卵率75%和杂交受精率73-91%的效果。     

Effects of Frying-Chilling-Reheating on the Lipid Content and Fatty Acid Composition of Cultured Sturgeon (Huso huso,Beluga) Fillets

Slices of Huso huso were fried, chilled, and then reheated to evaluate for the changes in lipid characteristics. The total lipid content of raw sample was 3.09 g/100 g which consists of 29.1 g/100 g saturated fatty acids (SFAs), 42.554 g/100 g monounsaturated fatty acids (MUFAs), and 28.126 g/100 g polyunsaturated fatty acids (PUFAs). In fried samples, levels of C18 fatty acid groups, MUFAs, PUFAs, and n6/n3 ratio increased while SFAs, EPA, and DHA content decreased. Upon chill storage, C18:2 fatty acid and n6/n3 ratio decreased while n3 fatty acids increased slightly. Free fatty acid (FFA) decreased after frying, but peroxide value (PV) increased with subsequent decrease at chilled condition.     

The Influence of Different Dietary Carbohydrate to Lipid Ratios on Some Qualitative Characteristics of Fillets of Beluga (Huso huso) During Refrigeration

In this study, juvenile beluga (Huso huso) were fed diets containing different carbohydrate to lipid ratios for 5 months. At the end of the culture period, proximate compositions of the fish carcasses (moisture, protein, fat, and ash) were measured. Then, qualitative changes in the fishes were evaluated during 24-days refrigeration (4°C), along with changes in their total volatile bases nitrogen (TVN), thiobarbituric acid (TBA), free fatty acids (FFA), pH, and muscle texture profile analysis. The results of proximate analysis of the carcasses showed that moisture, protein, and ash of the carcasses increased significantly (p < 0.05) with higher carbohydrate to lipid ratio, but fat content of the carcasses decreased significantly (p < 0.05). Further, during refrigeration, TVN, TBA, and FFA increased significantly in all the samples (p < 0.05), but these changes did not follow the same pattern in all the treatments. Tissue hardness decreased during preservation. Although pH changes in the fillets were low, they were significant and without a clear-cut pattern. The results showed that use of different carbohydrate to lipid ratios in diet does not lead to clear-cut changes in qualitative characteristics of beluga fillets during refrigeration.     

Effects of dietary L‐carnitine level on growth performance,body composition and antioxidant status in beluga (Huso huso L. 1758)

A 17‐week feeding trial was carried out to evaluate the effects of dietary L‐carnitine level in beluga, Huso huso. A total of fish averaging 1247 ± 15.6 g (mean ± SD) were randomly distributed into 18 fibreglass tanks, and each tank holding 10 fish was then randomly assigned to one of three replicates of six diets with 50, 150, 350, 650, 950 and 1250 mg L‐carnitine kg^?1 diet. At the end of 17 weeks of feeding trial, average weight gain (WG), feed efficiency (FE), protein efficiency ratio (PER) and condition factor (CF) of fish fed 350 mg kg^?1 diet were significantly (P < 0.05) higher than those of fish fed 50, 150, 950 and 1250 mg kg^?1 diets. WG, FE, PER and CF of beluga fed 650 mg kg^?1 diet were also significantly higher than those of fish fed 50, 950 and 1250 mg kg^?1 diets. Whole body and muscle protein were significantly improved by the elevation of dietary L‐carnitine level up to 350 mg kg^?1. Liver superoxide dismutase and glutathione peroxidase activities of fish fed 350 and 650 mg kg^?1 diets were significantly higher than those of fish fed 50, 950 and 1250 mg kg^?1 diets. The dietary L‐carnitine level of 350–650 mg kg^?1 diet could improve growth performance, feed utilization, protein‐sparing effects of lipid, antioxidant defence system and reproductive success. Polynomial regression of WG suggested that the optimum dietary L‐carnitine level was 480 mg kg^?1 diet. Therefore, these results may indicate that the optimum dietary L‐carnitine could be higher than 350 but <650 mg kg^?1 diet in beluga reared in intensive culture conditions.     

Evaluation of the optimum dietary protein level for the maximum growth of juvenile beluga (Huso huso L.1758)

A 10‐week feeding trial was carried out to evaluate the optimum dietary protein level for the maximum growth of juvenile beluga, Huso huso. Fish averaging 1.34 ± 0.07 g (mean ± SD) was randomly distributed into 18 circular fibreglass tanks of 500 L capacity (20 fish per tank). Six iso‐caloric diets were formulated to contain 30 (CP₃₀), 35 (CP₃₅), 40 (CP₄₀), 45 (CP₄₅), 50 (CP₅₀) and 55% (CP₅₅) crude protein (CP). Fish were fed each of the six experimental diets in triplicate groups. At the end of feeding trial, weight gain (WG) and specific growth rate (SGR) in fish fed CP₄₀ and CP₄₅ diets were significantly higher than those of fish fed CP₃₀, CP₃₅, CP₅₀ and CP₅₅ diets (P < 0.05). Lipid retention increased significantly from 24.7% to 31.6%, but protein retention decreased from 54.6% to 35.6% with increasing protein levels from 30% to 50%. Muscle total essential and non‐essential amino acid (EAA & NEAA) concentrations increased with the dietary protein level up to CP₄₅ diets. Muscle total EAA concentrations (%) of fish fed CP₄₅ were significantly higher than those of fish fed CP₃₀, CP₃₅, CP₅₀ and CP₅₅, but there was no significantly different between those of fish fed CP₄₀ and CP₄₅. Muscle total NEAA concentration (%) of fish fed CP₄₅ were significantly higher than those of fish fed CP₃₀ and CP₃₅ diets. Broken‐line analysis of WG suggested that the optimum dietary protein level could be 38.9% for maximum growth performance in juvenile beluga (1.3–77 g).     

The effect of diets containing different levels of active charcoal on growth performance,body composition,haematological parameters and possibility of heavy metals detoxification in big sturgeon (Huso huso)

In order to determine the chelating effect of activated charcoal, a total of 150 beluga (270 g) were fed for 60 days with a diet containing 0 (control), 5, 10, 15 and 20 g activated charcoal per kg. Afterwards, the fish were subjected to challenging with 1 mg/L of each of heavy metals including lead, cadmium and copper during seven days. As results, the highest percentage of body weight gain, specific growth rate, condition factor, protein efficiency ratio and the lowest feed conversion ratio before and after challenging with heavy metals were obtained in 15 g treatment with significant differences comparing to other treatment (p < .05). In all treatments, considerable differences were observed between two experimental stages of all parameters except condition factor and feed conversion ratio (p < .05). No mortalities were observed during the experiment. Before challenging with heavy metals, 15 g treatment showed the lowest activities of AST and ALT enzymes, and uric acid, protein, albumin and cholesterol amounts. The minimum amounts of creatinine and glucose were recorded in the control and 20 g treatments respectively. The highest levels of these parameters, except for creatinine and uric acid, were measured in the control group. After challenging with heavy metals, the lowest levels of AST and ALT enzyme activities, uric acid, creatinine, and glucose, and the highest amounts of protein, albumin and cholesterol belonged to 15 g, whereas the results in the control group were almost opposite. In all treatments, significant differences were observed between two experimental stages of all parameters except AST, uric acid, glucose and cholesterol (p < .05). In the pre‐challenge stage, the maximum amount of carcass protein was observed in 15 g while the differences in lipid content were not significant (p > .05). Moreover, the highest contents of moisture and ash were measured in the control group and 20 g respectively. After the challenge, the highest values of protein and lipid were quantified in 15 g, while the maximum values of ash and moisture were observed in 20 g and control group respectively. Also, significant differences were observed just in ash and moisture amounts in both stages (p < .05). Accumulations of cadmium, copper and lead were maximal in the control group in both stages, and their amount were decreased in sample with 15 g of activated charcoal until they reached to their lowest value in sample with 20 g of activated charcoal. The only different parameter between two treatments was copper amount. Also, significant differences were observed in all treatments in both stages (p < .05). Although activated charcoal at 20 g/kg diet yielded the best results in metal chelation, it is recommended to add 15 g/kg of activated charcoal to the diet of beluga because of other parameters.     

30种中草药对鲟鱼源海豚链球菌的体外抑菌作用

为研究黄连等30种中草药对鲟鱼源海豚链球菌的抑菌、杀菌作用,通过水煎煮法对30种中草药进行提取,采用牛津杯打孔法,在观察鲟鱼源海豚链球菌对30种中草药敏感性的基础上,进一步采用二倍稀释法测定中草药对鲟鱼源海豚链球菌的最小抑菌质量浓度和最小杀菌质量浓度。试验结果表明,鲟鱼源海豚链球菌对黄连、黄芩、连翘、丁香高度敏感,其中黄连的体外抑菌效果最佳,抑菌圈直径为(28.35±0.65) mm;对秦皮、山楂、女贞子、苦楝皮、石榴皮等均中度敏感;对丹参、猪苓、苍术、茯苓、贯众和生首乌低度敏感。黄连、黄芩、连翘、丁香、秦皮对鲟鱼源海豚链球菌的最小抑菌质量浓度和最小杀菌质量浓度分别为1.95 mg/mL和3.90 mg/mL、1.95 mg/mL和15.62 mg/mL、3.90 mg/mL和7.81 mg/mL、3.90 mg/mL和15.62 mg/mL、7.81 mg/mL和7.81 mg/mL,其余中草药对病原菌的最小抑菌质量浓度和最小杀菌质量浓度均高于15.62 mg/mL和31.25 mg/mL。综上可知,黄连、黄芩、连翘、丁香、秦皮对鲟鱼源海豚链球菌具有较好的防治效果。     

达氏鳇养殖群体的胚胎发育研究

为了解达氏鳇Huso dauricus养殖群体的胚胎发育过程,采用人工半干法受精获取受精卵,研究了在水温为(16.0±0.2)℃条件下达氏鳇养殖群体的胚胎发育过程及其特征。结果表明:达氏鳇成熟卵呈圆球形,为黄褐色或灰褐色,不透明,平均卵径为3.19 mm,属沉性黏性卵;达氏鳇受精卵历时136 h孵化出膜,所需总积温为2148~2592℃·h;达氏鳇受精卵的卵裂方式为特殊的辐射状卵裂;原肠中期时动物极细胞覆盖胚胎2/3,心跳期心脏呈"c"型,尾末端到达间脑或中脑时大量仔鱼出膜;根据胚胎发育过程的形态特征,可将达氏鳇胚胎分为受精卵、卵裂、囊胚、原肠、神经胚、器官形成、心跳和出膜期8个发育阶段,共36个时期。研究表明,达氏鳇胚胎发育过程中所需积温略高于鲟科其他鱼类。     

Growth efficiency, body composition, survival and haematological changes in great sturgeon (Huso huso Linnaeus, 1758) juveniles fed diets supplemented with different levels of Ergosan

Growth performance, carcass quality, survival and haematological responses were determined when Huso huso juvenile (41.7±1.8 g) fed diets containing Ergosan (an algal product) at 0, 2.0, 4.0 and 6.0 g kg⁻¹ for 60 days. Each diet was fed to triplicate groups of fish at 10-day intervals (1–10, 20–30 and 40–50 with non-supplemented diets and 10–20, 30–40 and 50–60 with supplemented diets). Results showed that fish fed diets containing Ergosan had significantly higher growth than the control group ( P <0.05). Survival was not different among all dietary treatments ( P >0.05). Food conversion ratio in the fish fed a diet containing 4.0 and 6.0 g kg⁻¹ Ergosan was significantly better than the other treatments ( P <0.05), whereas protein efficiency ratio was not different between experimental diets. Lymphocyte count in the fish fed diets containing Ergosan was higher than the other treatments. Haematocrit, haemoglobin (Hb) concentration, number of erythrocytes, total leucocytes, monocyte, eosinophil, myelocyte, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration were not different between treatments. Neutrophil count in the control group was higher than the fish fed supplemented diets. Furthermore, whole body lipid, moisture and fibre were not different among dietary treatments ( P >0.05) but body protein in the fish fed a diet containing Ergosan at the level of 2.0 and 4.0 g kg⁻¹ was higher than the other treatments. Whole body ash content was higher in the control group. It was concluded that dietary administration of Ergosan can influence some growth and haematological parameters in great sturgeon, H. huso juveniles.