Effects of Dietary Ascorbic Acid on Growth Performance,Body Composition,and Some Immunological Parameters of Caspian Brown Trout,Salmo trutta caspius

A 9‐wk feeding experiment was conducted to investigate the effect of dietary ascorbic acid (AA) on growth performance and tissue compositions of Caspian brown trout. The fish (9.64 ± 0.62 g) were held in tanks at a density of 40 fish per tank. Five experimental diets were prepared by providing of 9.8, 43.8, 89.4, 188.5, and 384.2 mg AA equivalent/kg diet, respectively. At the end of the trial, an increasing trend was found on growth performance with the increase of AA supplementation. Fish fed diet supplemented with more than 188.5 mg/kg AA also had significantly higher bone collagen than fish fed diets containing 9.8 mg/kg AA (P < 0.05). According to the broken line, the dietary AA requirement of Caspian brown trout fingerlings was 177.24 mg AA/kg diet based on the weight gain, 186.97 mg AA/kg diet based on the protein tissue, and 163.95 mg AA/kg diet based on the bone collagen. Serum lysozyme and alternative complement pathway activities were also influenced by graded level of AA supplementation to the diet. The present research clearly indicated that AA is required for normal growth and enhancement of immune response in Caspian brown trout fingerlings.     

Changes in Sperm Production,Sperm Motility,and Composition of Seminal Fluid in Caspian Brown Trout,Salmo trutta caspius,Over the Course of a Spawning Season

This study was carried out to evaluate milt quality in male Caspian brown trout (Salmo trutta caspius) over the course of the winter spawning season. Milt samples were collected biweekly during December and January. Chemical composition of seminal fluid, sperm production (milt volume, sperm density, spermatocrit,) and sperm motility characteristics (percentage and duration of motility) were measured. Milt volume, sperm density, osmolality, seminal minerals (Ca²⁺, Mg²⁺, K⁺, Na⁺, Cl^?), and total protein gradually decreased over the spawning season. Glucose and triglyceride content of milt did not show significant changes over the spawning season. Milt pH and the percentage and duration of motility were comparatively stable, declining only at the end of the season. Significant positive correlations were found between sperm density and seminal minerals, total protein and spermatocrit; percentage of motile spermatozoa and seminal minerals, total protein; and duration of motility and K⁺, Cl^?, total protein, and pH. Results show that season has a significant influence on milt quality in male Caspian brown trout, with the best milt being available at the beginning of spawning season.     

Contribution of Genetic and Environmental Variance Components to Increasing Body Length in Juvenile Brown Trout Salmo trutta

Genetic and environmental components of variance of body length in juvenile brown trout Sabno trutta were estimated from the results of three experiments. The additive genetic variance increased in the first months posthatch, but was gradually overwhelmed by environmental and residual variances, so that heritability, after going through a maximum (about 0.45) at 3 mo, decreased later on. However, constancy of genetic factors was indicated by high genetic correlations (0.8-1.0) observed between successive measurements. Maternal effects were visible, but not statistically significant. There was no evidence of non-additive genetic variation. These results suggest that selection for precocious growth among separate families should be performed at the time when heritability is about maximum. Accounting for the importance of the within-lot variation (80-90% of the total variation), individual selection should be considered, as compared to more expensive methods.     

养殖密度对食用褐鳟Salmo trutta生长和水质的影响

在涌泉水温度5.6~10.5℃下,将体质量(17.52±0.22)g的2龄褐鳟Salmo trutta饲养在流水圆柱形平底玻璃钢(半径45cm,高60cm)水槽中,水深40cm,密度分别为6.8kg/m~3(SD1)、10.4kg/m~3(SD2)、14.0kg/m~3(SD3)、17.5kg/m~3(SD4)、21.0kg/m~3(SD5)和24.5kg/m~3(SD6),每个密度组设3个重复,探讨养殖密度对褐鳟生长的影响。70d的饲养结果表明:本试验范围内的放养密度未显著影响2龄褐鳟的存活率(P0.05),净增重随养殖密度的增加而增大。SD5组褐鳟净增重(116.55g/(m~2·d))最大;SD4组褐鳟的日增重(0.25g/d)、增重率(102.07%)和特定生长率(1%/d)显著高于SD3组(P0.05)。随着养殖密度的增加,溶解氧含量(DO)呈极显著下降趋势(P0.01),SD1、SD2、SD3(10.14~11.84mg/L)组极显著高于SD5、SD6组(9.62~11.53mg/L)(P0.05);养殖29d和50d时SD1组NO_2~-含量(0.02~0.06mg/L)与SD3、SD5、SD6组(0.04~0.06mg/L)差异显著(P0.05),其他时间不显著;36d后SD2、SD3(0.17~0.22mg/L)组的NH4-NT显著低于SD6组(0.25~0.38mg/L)(P0.05)。比较分析认为,2龄褐鳟的最佳养殖密度应为17.5kg/m~3,不要低于10.4kg/m~3。     

Dietary nucleotide supplements influence the growth,haemato‐immunological parameters and stress responses in endangered Caspian brown trout (Salmo trutta caspius Kessler, 1877)

A feeding trial was conducted to evaluate the effects of Optimûn, a commercial nucleotide (NT) product, on the growth, haemato‐immunological and serum biochemical parameters and stress responses of Caspian brown trout fingerlings (average initial weight of 12.26 g). A basal diet was supplemented with levels of 0 (control), 1.5, 2.5, 3.5 and 5 g NT kg^?1 to formulate five experimental diets. After 8 weeks of feeding trial, fish fed diet with 2.5 g NT kg^?1 had the highest final weight compared with other treatments. The fish fed diets with 2.5 g NT kg^?1 had higher blood protein, albumin, albumin/globulin ratio, red blood cells, white blood cells and lymphocyte content and lower alkaline phosphatase. The lysozyme activity in serum was found to be significantly (P < 0.05) greater in fish fed diet with 2.5 g NT kg^?1. Concerning both stressors (confinement and salinity stress), fish fed diet with 2.5 g NT kg^?1 had lower plasma cortisol and glucose levels. Thus, administration of 2.5 g kg^?1 of the Optimûn dietary nucleotide formula is recommended to promote growth and immunity as well as to enhance stress responses of Caspian brown trout.     

饲料蛋白质和能量水平对草鱼幼鱼生长和消化酶活性的影响

在水温24～29℃下,将675尾规格整齐、健康、体质量为（35.59士0.44）g的草鱼（Ctenopharyngodon idel-lus）随机分为9个处理,每处理3个重复,放养于水泥池中的网箱（100cm×50cm×100cm）内,投喂以鱼粉和豆粕为蛋白源,豆油作为脂肪源配制的3个蛋白水平（24%、28%、32%）,每一蛋白水平设3个脂肪水平（4%、6%、8%）,共计9种饲料。饲料蛋能比（P/E）在15.81-22.46 mg·kJ-1之间。92d的饲养表明：D4组（蛋白质含量为28.02%,脂肪为4.30%）草鱼的特定生长率最高,显著高于其他各组（P〈0.05）。随着饲料中蛋白含量的增加,草鱼全肠中蛋白酶的活力逐渐升高,之后又降低,以D4组饲料的蛋白酶活性最高,显著高于D1、D8和D9（P〈0.05）。本实验表明,该生长阶段的草鱼所需最适蛋白水平为28.02%,能量为14307kJ.kg-1,P/E约为19.58mg·kJ-1。     

发酵豆粕替代藻粉对刺参(Apostichopus japonicus)生长及体组成的影响

为研究发酵豆粕替代藻粉对刺参(Apostichopus japonicus)生长及体组成的影响,以发酵豆粕分别替代基础饲料中的藻粉及鱼粉藻粉混合物(2:15),配制9组等氮实验饲料,饲喂初始体重为17.7 g左右的刺参幼参70 d.结果显示,随替代藻粉比例的升高,实验刺参的增重率及特定生长率先升后降(P＜0.05);随替代混合物比例的升高,D8、D9组增重率及特定生长率显著低于前3组(P＜0.05),但前3组之间无显著差异(P＞0.05);替代藻粉降低了体壁粗脂肪含量(P＜0.05);替代混合物降低了粗灰分含量(P＜0.05);替代藻粉降低了体壁甘氨酸、蛋氨酸及半胱氨酸含量(P＜0.05),提高了苯丙氨酸和组氨酸含量(P＜0.05);替代混合物降低了丝氨酸、苏氨酸、甘氨酸、蛋氨酸、赖氨酸及组氨酸含量(P＜0.05),提高了精氨酸、脯氨酸、苯丙氨酸及半胱氨酸含量(尸＜0.05);替代藻粉降低了体壁Ca、Mg、Fe、Zn、Cu、Cr、Mn及Pb含量(P＜0.05);替代混合物降低了Ca、Mg、Zn、Cu、Cr及Pb含量(P＜0.05),提高了Fe及Mn含量(P＜0.05).以增重率为评价指标,经SAS REG曲线拟合,发酵豆粕替代藻粉的最佳比例为29.75％;经SAS NLIN曲线拟合,替代46.46％的鱼粉藻粉混合物对刺参生长无显著影响.     

不同糖源对拟穴青蟹仔蟹的生长、体成分及消化酶的影响

在水温26~30℃,盐度18~22条件下,初始体质量(0.012±0.000)g的拟穴青蟹仔蟹饲养在底铺1~2 cm细沙、边缘放5 cm^2瓦片的塑料水桶(直径20 cm,水深20 cm)中,投喂以葡萄糖、蔗糖、糊精、木薯淀粉、玉米淀粉、糊化木薯淀粉和糊化玉米淀粉为糖源的7种等氮等能饲料,养殖3周,研究不同糖源对拟穴青蟹仔蟹生长、体组成及消化酶活性的影响。试验结果显示,不同糖源显著影响拟穴青蟹仔蟹的生长性能(P<0.05);质量增加率和特定生长率依次为糊化木薯淀粉>糊化玉米淀粉>木薯淀粉>玉米淀粉>糊精>蔗糖>葡萄糖;葡萄糖试验组的成活率显著低于其他各组(P<0.05)。不同糖源对拟穴青蟹仔蟹体组成中粗蛋白和粗脂肪含量影响显著(P<0.05),对仔蟹的水分和灰分含量影响不显著(P>0.05);不同糖源对3种消化酶活性影响显著(P<0.05)。拟穴青蟹仔蟹对大分子糖源的生物利用度要大于小分子糖源。在本试验的研究条件下,7种常见糖源中糊化木薯淀粉是拟穴青蟹仔蟹的最适糖源。     

Effects of Dietary Carbohydrate‐to‐lipid Ratio on Growth Performance,Body Composition,Digestive Enzyme Activities,and Hepatic Enzyme Activities in Juvenile Large Yellow Croaker,Larimichthys crocea

An 8‐wk feeding trial was conducted to investigate the effects of dietary carbohydrate‐to‐lipid ratios (CHO : L) on growth performance, body composition, digestive enzyme activities, and hepatic enzyme activities of juvenile large yellow croaker, Larimichthys crocea. Six isonitrogenous (45% crude protein) and isoenergetic (18 kJ/g gross energy) diets with varying CHO : L ratios (0.07, 0.48, 1.20, 2.19, 4.81, and 10.48) were fed to triplicate groups of large yellow croaker in floating sea cages. Results showed that the highest specific growth rate (SGR) was found in fish fed diets with CHO : L ratio of 2.19. Fish fed the lower (0.07 and 0.48) CHO : L ratios tended to produce lower growth (P < 0.05). The whole‐body lipid content significantly decreased, while hepatosomatic index, liver glycogen content, and plasma glucose concentration significantly increased as dietary CHO : L ratios increased (P < 0.05). Plasma total cholesterol, triglyceride, and low‐density lipoprotein cholesterol concentrations significantly decreased with elevated dietary CHO : L ratios (P < 0.05). The increasing dietary CHO : L ratios significantly stimulated the activities of intestinal amylase and hepatic pyruvate kinase and depressed the activity of hepatic phosphoenolpyruvate carboxykinase (P < 0.05). Based on a second‐order polynomial regression analysis of SGR, 2.38 was determined as the optimal dietary CHO : L ratio for juvenile large yellow croaker.     

Effects of Dietary Lipids on the Growth Performance,Survival, and Digestive Enzymes of Juvenile Cuttlefish,Sepia lycidas

This study was conducted to determine the effects of dietary lipids on the growth performance, muscle composition, and enzyme activities of the stomach, intestines, and liver of Sepia lycidas juveniles. Fish oil and soybean lecithin were selected as lipid sources to formulate six experimental diets containing lipid levels of 3.68, 4.15, 6.62, 8.09, 9.56, and 11.03%. The feed efficiency first declined and then rose, with the lowest value obtained in individuals fed the 8.09% lipid content diet; the protein efficiency ratio significantly decreased with an increased lipid level. The highest crude protein content and lowest crude lipid content were simultaneously obtained in individuals fed the 9.56% lipid content diet. The activities of pepsase, trypsin, and intestine lipase initially increased before decreasing. The highest activities of protease, trypsin, and lipase were obtained in individuals fed the 9.56% lipid content diet, while the highest activity of amylase was obtained in individuals fed the 6.62% lipid content diet. Hepatic glutamate pyruvate transaminase and glutamic oxaloacetic transaminase initially increased and then held steady, with the highest activities simultaneously obtained in individuals fed the 9.56% lipid diet. Our results suggest that dietary lipids at a level of 9.56% could be the optimal lipid requirement for S. lycidas to grow and maintain normal metabolism.     

Effect of Dietary Carbohydrate‐to‐lipid Ratios on Growth Performance,Body Composition,Hepatic Enzyme Activities,and Digestive Enzyme Activities of Juvenile Australian Redclaw Crayfish,Cherax quadricarinatus (von Martens)

A growth experiment was conducted to determine the optimal dietary carbohydrate‐to‐lipid (CHO : L) ratio for the Australian redclaw crayfish, Cherax quadricarinatus (von Martens). Specimens were divided into five treatment groups and fed twice a day to apparent satiation with isonitrogenous and isoenergetic diets with dietary CHO : L ratios of 10.75:1, 5.99:1, 3.60:1, 2.18:1, or 1.33:1. Over the 8‐wk growth trial, redclaw crayfish fed the 2.81:1 and 3.60:1 diets exhibited better weight gain (WG), specific growth rate (SGR), and feed conversion ratio (FCR) than specimens fed the other diets (P < 0.05). Activities of hexokinase and pyruvate kinase were stimulated by elevated levels of dietary carbohydrate, whereas activities of lipase and alkaline phosphatase were stimulated by elevated levels of dietary lipid. Dietary CHO : L ratios significantly affected digestive enzyme activities (P < 0.05), except for trypsin (P > 0.05). On the basis of the analysis of growth, FCR, and costs of culturing redclaw crayfish, the optimal growth and costs occurred when the dietary carbohydrate and lipid levels were 290.10 g/kg and 80.70 g/kg, respectively, corresponding to a CHO : L ratio of 3.60:1. These results indicate that a CHO : L ratio of 3.60:1 is optimal for rearing redclaw crayfish and that this species uses carbohydrate more efficiently than lipid.     

鸡肉粉替代鱼粉对大菱鲆生长和体组成的影响

以鸡肉粉替代饲料中0%、20%、40%、60%、80%的鱼粉,配制5种等氮等能饲料。选取初始体质量为(22.82±0.08)g的大菱鲆幼鱼180尾,随机分为5组(每组3个重复,每重复12尾)分别投喂一种饲料,试验周期为8周。试验结果表明,鸡肉粉替代鱼粉对大菱鲆幼鱼终末体质量、特定生长率、饲料系数以及质量增加率产生显著影响(P0.05)。鸡肉粉替代鱼粉对大菱鲆幼鱼鱼体水分、粗蛋白、灰分、能量含量未造成显著影响(P0.05),鸡肉粉替代组粗蛋白含量比对照组略微升高,粗脂肪含量比对照组显著降低(P0.05),鸡肉粉替代组之间的粗脂肪含量无显著差异(P0.05),但有升高的趋势。鸡肉粉替代40%鱼粉时,血清谷草转氨酶、谷丙转氨酶活力显著高于对照组(P0.05)。鸡肉粉替代鱼粉对肝脏谷丙转氨酶、谷草转氨酶活力影响显著(P0.05)。鸡肉粉替代鱼粉对主要营养成分的表观消化率产生显著影响(P0.05)。本试验结果表明,鸡肉粉替代20%的鱼粉对大菱鲆幼鱼生长最为有利。     

Effect of Dietary Antarctic Krill Meal on Growth Performance,Muscle Proximate Composition,and Antioxidative Capacity of Juvenile Spotted Halibut,Verasper variegatus

A 7‐wk feeding trial was conducted to evaluate the effects of dietary Antarctic krill meal (AKM) on the growth performance, proximate composition of muscles, and antioxidative capacity of juvenile spotted halibut. Six diets were formulated to contain about 50% protein and 8% lipid. A control diet (R0) without AKM and the other five diets with 8.1, 16.2, 24.3, 32.4, and 42.5% AKM supplementation (R10–50) to replace 10, 20, 30, 40, and 50% fishmeal protein were used to feed to juvenile spotted halibut. The juveniles were fed with each diet using three replicates and cultivated in the indoor culture system. Results showed that the specific growth rate, feed intake, and protein efficiency ratio in the R30 and R40 groups were significantly higher than that in other groups (P < 0.05). Survival rate in the R50 group was significantly lower compared with the R0 group and the other four AKM supplementation groups. Moreover, the rising AKM levels in diets had significant effects on the chemical composition of juvenile spotted halibut, showing significantly decreased contents of crude protein, but increased lipid and ash contents (P < 0.05). The total superoxide dismutase activity and catalase activity of serum and liver in AKM groups were significantly higher than those in the control group (P < 0.05). In contrast, the contents of malondialdehyde in serum and liver were significantly lower compared with the control group. These findings illustrate that a moderate AKM level in diets can significantly improve the growth performance, feed utilization, and antioxidative capacity in juvenile spotted halibut, which support the finding that AKM may be used as a good protein source for halibut in the aquafeed industry.     

Effect of Dietary Safflower and Canola Oil on Growth Performance,Body, and Fatty Acid Composition of Rainbow Trout (Oncorhynchus mykiss)

The objective of the present study was to evaluate the effects of the diets enriched with safflower and canola oil on growth, feed utilization, body composition, liver, and muscle fatty acid composition of rainbow trout (Oncorhynchus mykiss). Rainbow trout having approximate initial weight of 97.03 ± 0.10 g were fed the experimental diets containing only fish oil (Group 0SFO), safflower oil (50% safflower oil, Group 50SFO and 33% safflower oil, Group 33SFO), and vegetable oil blend (33% safflower and 33% canola oil, Group 66SFCO) for 45 days. Twenty-five fish were randomly assigned for triplicate treatments and offered the test diets two times daily to apparent satiation. At the end of the experiment, survival was 100% in all treatments. No significant differences in the weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio were found between fish fed with the different experimental diets. The highest hepatosomatic index (HIS) and viscerasomatic index (VSI) was obtained in 50SFO and 33SFO groups, respectively. The moisture, protein, lipid, and ash content in the body composition of the fish increased in all experimental groups. The lipid content was not significantly different among the groups (p > 0.05); however, there was a significant difference in ash content between the control and the other groups (p < 0.05). The experimental diets containing vegetable oil (50SFO and 33SFO groups) and vegetable oil blend (66SFCO group) had significantly higher concentrations of n-6 fatty acids, predominantly in the form of linoleic acid (LA). The n-3 fatty acids were present in significantly higher concentration in the control treatment (0SFO). The fatty acid composition of fish fillet and liver were reflective of the dietary lipid source. While the fillet and liver of fish fed the 50SFO diet was high in linoleic acid (18:2 n-6), fish fed the 66SFCO diet had high concentrations of oleic acid (OA; 18:1 n-9). The present study suggests that fish oil can be replaced by up to 50% with safflower oil and by up to 66% with safflower + canola oil blend in rainbow trout diets with no significant effect on growth.     

拟微绿球藻粉替代鱼粉对大菱鲆幼鱼生长性能、体组成和血清生化指标的影响

为探讨拟微绿球藻(Nannochloropsis sp.)粉替代鱼粉对大菱鲆(Scophthalmus maximusL.)幼鱼生长性能、体组成和血清生化指标的影响,用拟微绿球藻粉替代基础饲料中0%、3.88%、7.76%、11.64%和15.52%的鱼粉,配制成5种等氮等能的饲料(N_0、N_(3.88)、N_(7.76)、N_(11.64)、N_(15.52))。选取初始体重为(24.60±0.02) g的大菱鲆幼鱼600尾,随机分成5组,每组3个重复,每个重复40尾鱼,养殖周期70d。结果显示:1)各实验组大菱鲆幼鱼的增重率(WGR)、特定生长率(SGR)、蛋白质效率(PER)、饲料系数(FCR)、日摄食率(DFI)、肥满度(CF)和成活率(SR)均无显著差异(P0.05);2)随着藻粉添加量的增加,全鱼及肌肉中粗脂肪含量显著降低(P0.05),粗蛋白、粗灰分和水分含量无显著差异(P0.05);3)血清溶菌酶(LZM)、补体蛋白C3、补体蛋白C4及酸性磷酸酶(ACP)活力均呈先上升后下降的趋势,分别在N_(7.76)、N_(7.76)、N_(11.64)、N_(7.76)组达到最大值,且显著高于N_0组(P0.05),N_(15.52)组碱性磷酸酶(ALP)显著低于其他组(P0.05),其他组之间无显著差异(P0.05);4)藻粉组血清总超氧化物歧化酶(T-SOD)、总抗氧化能力(T-AOC)和谷胱甘肽过氧化物酶(GSH-PX)活力,均呈先上升后下降的趋势,在N_(7.76)组达到最大值,且显著高于N_0组(P0.05);5) N_(7.76)组血清甘油三酯(TG)含量显著低于其他组(P0.05),其他组之间无显著差异(P0.05),藻粉组血清总胆固醇(TCHO)显著低于N0组(P0.05),各藻粉组之间差异不显著(P0.05);6)藻粉组血清谷草转氨酶(AST)活力呈先下降后上升的趋势,N_(11.64)组达到最小值,显著低于N_0组(P0.05),藻粉组谷丙转氨酶(ALT)活力显著低于N_0组(P0.05)。研究表明,本实验条件下,拟微绿球藻粉替代大菱鲆幼鱼饲料中15.52%的鱼粉对其生长无显著影响,替代7.76%可显著提高其非特异性免疫力,降低血脂水平。     

饲料蛋白水平对眼斑双锯鱼幼鱼生长性能和体成分的影响

为确定眼斑双锯鱼幼鱼人工配合饲料中合适蛋白水平,试验研究了饲料蛋白水平对眼斑双锯鱼幼鱼生长、饲料转化率和体成分的影响。养殖试验在循环水系统中进行,初始体质量为(0.085±0.002)g的幼鱼随机分配到6个处理组(每组3个平行,每个平行40尾),分别投喂蛋白水平38.11%、40.91%、44.16%、47.21%、50.02%和53.16%的人工饲料,试验持续56d。不同蛋白水平饲料对眼斑双锯鱼幼鱼质量增加率、特定生长率、饲料系数、蛋白质效率以及全鱼的体成分等均有显著影响。饲料蛋白水平为38.11%~50.02%时,随着饲料蛋白水平的增加,眼斑双锯鱼幼鱼的质量增加率和特定生长率呈增加的趋势,饲料蛋白水平为53.16%时略有下降。经回归分析,当饲料蛋白水平为51.8%时,质量增加率最大;蛋白水平为51.1%时,特定生长率最大。饲料系数也随着饲料蛋白水平增加而呈现先降后升的趋势,饲料系数谷值出现在蛋白水平为47.21%试验组,而蛋白质效率则相反。经回归分析,当饲料蛋白水平为47.5%时,饲料系数最小;饲料蛋白水平为47.8%时,蛋白质效率最大。全鱼粗蛋白随饲料蛋白水平升高呈增加趋势,但到一定水平后维持该水平不再增加,而粗脂肪则随饲料蛋白水平升高呈先降后升的趋势。综合生长、饲料转化率和体成分等指标,本试验条件下眼斑双锯鱼幼鱼适宜的饲料蛋白水平为47.5%~51.8%。     

Antibiotics,Penicillin and Sreptomycin improve semen quality indices of endangered Caspian brown trout,Salmo trutta caspius (Kessler, 1870) during in vitro short‐term storage

In this study, we examined the effects of 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate on semen quality indices of endangered caspian brown during 12 days short‐term storage at 4°C. Twenty‐four millilitre semen samples with good quality were considered for the experiment. The semen samples were then stored in the presence and absence of 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate. The semen quality parameters including percentage and duration of sperm motility were measured 0, 3, 6, 9 and 12 days after storage. In the antibiotic receiving group, the values of percentage and duration of sperm motility reduced 3 and 6 days after storage respectively and reduced to lowest levels at day 12. In the antibiotic‐free group, the duration and percentage of sperm motility decreased significantly after 3 days of storage and reached to lowest values at day 12. Also, percentage and duration of sperm motility in each storage time were significantly higher in the antibiotic receiving group than in the antibiotic‐free group. The overall values of percentage and duration of sperm motility for all storage periods were higher in the antibiotic receiving group than in the antibiotic‐free group. In conclusion, our results demonstrated that 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate improves the viability of caspian brown trout during short‐term storage.     

维生素D3对仿刺参幼参生长、体组成及 抗氧化能力的影响

为研究维生素D3对仿刺参(Apostichopus japonicus)幼参生长、体组成及抗氧化能力的影响,在基础饲料中分别添加0(D1)、250(D2)、500(D3)、1000(D4)、2000(D5)、3000(D6) IU/kg的维生素D3(实测值：95、334、570、1076、2063、3081 IU/kg),制作6组等氮等能的实验饲料,饲喂初始体重为(15.43±0.14) g仿刺参幼参56 d。结果显示,1) 维生素D3对仿刺参存活率(SR)无显著影响(P>0.05),显著提高了增重率(WGR)和特定生长率(SGR),D1组均显著低于其他组(P<0.05);D3、D4、D5组肠体比(IWR)显著高于其他3组(P<0.05),但3组之间差异不显著(P>0.05)。2) 维生素D3对体壁水分、粗蛋白和粗脂肪含量无显著影响(P>0.05);粗灰分含量随添加量的增加呈先升后降趋势,D5组达到最高值;羟脯氨酸含量呈先下降后上升趋势,D4组达到最低值;维生素D3显著提高了体壁Ca含量(P<0.05);体壁维生素D3的沉积量呈先上升后下降趋势,D4组达到最高值,显著高于其他组(P<0.05)。P含量呈先上升后平稳趋势;Mg含量呈上升趋势,D1组显著低于其他组(P<0.05);Fe含量呈先升后降趋势,D5、D6组显著低于其他组(P<0.05);Mn含量呈下降趋势,但各组间差异不显著(P>0.05)。3) 随着维生素D3添加量的增加,肠道碱性磷酸酶(AKP)及总超氧化物歧化酶(T-SOD)活力呈先上升后下降趋势,丙二醛(MDA)含量呈下降趋势,各组间总抗氧化能力(T-AOC)及过氧化氢酶(CAT)活力均无显著性差异(P>0.05)。研究表明,以增重率为评价指标,一元二次线性回归分析表明,初始体重为15.43 g的仿刺参对维生素D3的最适需求量为1587.5 IU/kg。