海带豆腐制作工艺的优化

以大豆和海带为主要原料制作的海带豆腐具有很高的营养价值和医疗保健作用.采用4因素3水平的正交试验确定了海带豆腐的最佳工艺参数.即:海带添加量20%、葡萄糖酸内酯0.30%、凝固时间16min、凝固温度95℃.制作出的海带豆腐呈白色,凝固状态好、保水性好、有弹性、质地细腻,具有纯正的豆香味及海带特有的风味.     

Evidence of fish spillover from freshwater protected areas in lakes of eastern Ontario

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Quantifying contributions to tournament catches among resident,stocked and hybrid black basses (Micropterus spp.)

Millions of Florida bass, Micropterus floridanus Lesueur, are stocked annually into populations of largemouth bass, Micropterus salmoides Lacepède, to increase trophy fish abundance. However, little effort has related the role that resultant hybrids make to angler catches. Largemouth bass were sampled from an important recreational fishery subject to extensive Florida bass stocking to address the hypothesis that anglers capture Florida bass, largemouth bass and hybrids at rates equivalent to their overall abundance in the population. Fin clips obtained from tournament angling events (n = 348) and boat‐mounted electrofishing sampling (n = 219) were screened at 38 species‐diagnostic markers and individuals were assigned to genealogical classes using Bayesian clustering algorithms. No significant differences were identified between angler and electrofishing catches providing evidence that hybridised individuals stemming from a long‐term stocking programme may constitute an important contribution to tournament angling catch.     

Replacement of fishmeal by chicken plasma powder in diets for largemouth bass (Micropterus salmoides): Effects on growth performance,feed utilization and health status

The present study was conducted to explore the effects of graded replacing fishmeal (0, 50, 100 and 150 g/kg) with chicken plasma powder in diets for largemouth bass, and each diet was fed to triplicate groups of fish (initial weight: 49.50 ± 0.07 g) twice daily. Results showed that specific growth rate was not remarkably reduced until 150 g/kg fishmeal being replaced. Meanwhile, the inclusion of chicken plasma powder led to a significant decrease in feed intake, and the replacement of 150 g/kg fishmeal significantly decreased the apparent digestibility coefficient of protein and essential amino acids, which may account for the lowered protein retention rate and decreased crude protein content of liver and whole body composition. Moreover, the replacement of 150 g/kg fishmeal resulted in a significantly reduced activity of lysozyme, classical complement pathway and respiratory burst, and meanwhile, the red blood cell count and haemoglobin content were also significantly reduced, indicating the impaired health status of fish with high inclusion of chicken plasma powder. In above, approximately 50–100 g/kg fishmeal could be replaced by chicken plasma powder in the diets for largemouth bass.     

Price interactions between wild and farmed products: Turkish sea bass and sea bream markets

We investigate empirically market interactions in the Turkish wild and farmed sea bass and sea bream markets. For gilthead sea bream and European sea bass, we conduct a Granger causality test between the prices of the wild and farmed products, based on the estimation of a vector autoregressive model. Our data set consists of annual fish prices from 1996 to 2016. Our empirical results show that the wild and farmed sea bass are neither substitutes nor complements: the markets for each product are independent. However, in the case of sea bream, the price variations for farmed sea bream have a causal impact on the price of wild sea bream. Moreover, the price of wild sea bream Granger-causes the price variation of farmed sea bream. Thus, the wild and farmed sea bream markets are integrated.     

云纹石斑鱼胚胎发育及仔、稚、幼鱼形态观察

对云纹石斑鱼Epinephelus moara胚胎发育及仔、稚、幼鱼形态进行了观察与研究,详细描述了各发育期的形态特征和发育时间。结果表明:1)在水温22±0.2℃、盐度30、溶氧7.8mg/L、pH8.25的条件下,云纹石斑鱼的受精卵历时38h 17min开始孵化出膜。胚胎发育可分为受精卵、卵裂、原肠、神经胚和器官形成及出膜6个阶段,受精、胚盘形成、2细胞等28个时期。2)在水温23±1℃,盐度30±3,DO≥5mg/L,pH8.0±0.5的海水中,培育至5d,卵黄囊完全消失,成为后期仔鱼;培育至27d,发育最快的云纹石斑鱼结束仔鱼期,进入稚鱼期;培育至65d,发育最快的稚鱼完成变态,成为幼鱼。胚后发育过程主要是根据卵黄囊、鳍膜、鳞片、体色及第1腹鳍棘与第2背鳍棘相对长度的变化分为仔鱼、稚鱼和幼鱼3个时期。其中仔鱼期又根据其卵黄囊的有无划分为前期仔鱼和后期仔鱼。     

高效液相色谱法测定鲈鱼体中喹烯酮的残留

本文建立了用高效液相色谱法测定鲈鱼中喹烯酮残留量的方法。样品采用乙酸乙酯提取,正己烷净化,高效液相色谱法进行定量分析。结果表明,在0.02～1.0μg/mL范围内喹烯酮的响应值与浓度呈良好线性关系,线性回归方程为Y=4.96×104X?6.15×10-1,相关系数R=0.9998,方法定量限为50μg/kg。在添加浓度20μg/kg～200μg/kg,回收率在70.0%～92.6%之间,相对标准偏差为1.86%～3.30%。该方法前处理过程简便快捷,准确性高,结果可靠,可满足实验室大量、快速分析的需求。     

Apparent digestibilities of common feedstuffs for bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides using individual test ingredients

Apparent digestibility of dry matter and energy, and availability of amino acids from blood meal (BM), fish meal (FM), meat and bone meal (MBM), poultry by-product meal (PBM), soybean meal (SBM), corn, wheat and yellow grease (YG) were determined for bluegill Lepomis macrochirus (mean weight, 57 g), and likewise, but not for BM or wheat, for largemouth bass Micropterus salmoides (mean weight, 30 g). To avoid nutrient interaction from a reference diet, diets containing 98.5% (985 g kg⁻¹) of test ingredients were used, except for semi-solid, YG which was mixed with corn to permit pelletization. Faeces were collected by a siphoning method. Apparent dry matter digestibility values ranged from 50% (corn) to 87% (BM) for bluegill and from 53% (MBM) to 76% (PBM) for largemouth bass. Apparent energy digestibility values ranged from 53% (corn) to 92% (BM) for bluegill and from 63% (MBM) to 93% (YG) for largemouth bass. Apparent digestibility of most amino acids exceeded 90% for evaluated protein sources, except for MBM which showed slightly lower values (80–90%) for both fishes. Isoleucine digestibility from BM was relatively low (82%) for bluegill. High digestibility values for SBM, PBM and BM, indicate good potential for replacing FM in diets for both fishes.     

Development and distribution of intestinal enzymatic activity in Paralabrax maculatofasciatus (Steindachner, 1868) larvae fed with live prey

We describe the development and distribution of intestinal aminopeptidase M, dipeptidyl aminopeptidase IV, non-specific esterase, alkaline phosphatase and acid phosphatase, using enzyme histochemistry techniques, in the spotted sand bass larvae ( Paralabrax maculatofasciatus ) under culture conditions. All digestive enzymes tested showed a positive reaction from first feeding (day 2) and throughout the study period (day 30). At first feeding, the main enzymatic activity was in the mucosa throughout the intestines. Later, enzymatic activity occurred in the liver, kidney and stomach. All enzymatic activities increased from days 15 to 20, remaining constant until the end of the study. This enzymatic activity suggests the onset of maturation of the digestive tract. After day 20, a positive reaction was recorded in the pyloric caeca for all tested enzymatic activities. Our study confirms the digestive and absorptive functions in the intestines in spotted sand bass larvae from first feeding. It also brings new insight to establish an early weaning strategy during cultivation of spotted sand bass larvae.     

Effects of oestradiol-17β or 17α-methyltestosterone administration on gonadal differentiation of largemouth bass Micropterus salmoides (Lacepède)

Monosex populations can be a valuable management tool in culture of larger size largemouth bass (>400 g). In this study, we investigated the effective mode and duration of oestrogen and androgen administrations to produce monosex largemouth bass populations. The experiment consisted of nine treatments. In oral administration groups, we fed 40-day-old fry either 200 mg of an oestradiol-17β (E₂) kg⁻¹ diet or 60 mg of a 17α-methyltestosterone (MT) kg⁻¹ diet for 30, 45 or 60 days. In bath treatments, we immersed fry in a 1 mg MT L⁻¹ solution for 5 h a day on three or six occasions. For control treatment, we fed fry an ethanol-treated diet for 45 days. The frequency of females in the control group was 53.1%. Oral administration of E₂ at all durations resulted in slight increases in the frequency of females (59.8–70.5%). Both modes of androgen administration at all durations were ineffective in altering phenotypic sex. The experimental results of our study indicated that male differentiation passed the point of being completely and functionally influenced by exogenous oestrogens, while female differentiation had already taken place and was no longer responsive to exogenous androgens in 40-day-old (33.5 mm) largemouth bass fry.