鱼蛋白粉的营养评价

对采用酶解法和酸水解法制备的白鲢鱼蛋白粉的营养成分进行了分析,从氨基酸组成上表明鱼蛋白粉具有较高的营养价值,在食品行业有较大应用前景。     

Effect of nutrient loading and retention time on performance of high rate algal ponds

Small pilot ponds in a glasshouse at the Scottish Agricultural College (Auchincruive) were used to investigate the effects of changing C:N:P loading rate and retention time on pond performance as measured by nutrient removal and dry matter biomass. One experiment investigated ponds operated at two C:N:P ratios: low (9:7:1) and high (104:10:1) and two retention times (4 and 7 days θ. Increasing retention time from 4 to 7 days increased the concentration of total (dry matter) and algal (chlorophyll a) biomass and the degree of nitrification. It also increased removal of phosphorus, but had no effect on nitrogen or COD removal. Cyanobacteria predominated in ponds operated at both 4 and 7 days, and the density of cyanobacteria increased with increased retention time. Nitrogen removal was independent of C:N:P ratio; indeed the lower C:N:P ratio favoured increased nitrification. A high C:N:P ratio increased phosphorus and COD removal and increased the concentration of algal biomass (chlorophyll a), but had little effect on total biomass (dry matter). A second experiment varied COD loading rate (600, 350 and 100 kg COD ha-¹ d-¹) while maintaining a constant retention time (either 5 or 7 days θ). Species composition was independent of retention time. The longer retention time increased both total and algal biomass concentration and also percentage of nitrogen removed. Nitrification was independent of retention time. Increasing loading rate increased dry matter production and resulted in a predominance of cyanobacteria over Chlorophyceae. Increased loading rate was related to increase in nitrogen removal, however more complete nitrification occurred at low COD loading rates. Phosphorus removal in the pond with 5-day (θ) remained constant independent of loading rate, but in the pond with 7-day θ phosphorus removal increased with increased COD loading. COD removal was independent of both retention time and loading rate. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of feed intake level on efficiency of microbial protein synthesis and nitrogen balance in Boran steers consuming tropical poor-quality forage

This study aimed at evaluating the effects of feed intake level on the efficiency of rumen microbial protein synthesis (EMPS), nitrogen (N) excretion, and N balance in twelve 18-months old Boran (Bos indicus) steers with initial average liveweight of 183 kg (standard deviation (SD) 15.2). The experiment followed a 4 × 4 complete Latin Square design with four dietary treatments tested in four periods. Each period ran for 5 weeks with 3 weeks of adaptation and 2 weeks of sample collection; separated by 2 weeks of re-feeding. Steers were fed at 100%, 80%, 60%, and 40% of their metabolisable energy requirement for maintenance (MER, referred to as MER100, MER80, MER60, and MER40, respectively). Steers receiving MER80, MER60, and MER40 were only fed Rhodes grass hay. MER100 steers were offered Rhodes grass hay at 80% of their MER and cottonseed meal and sugarcane molasses at each 10% of MER. Mean daily dry matter intake differed between treatments (p < 0.001) and ranged between 2.1 kg/animal (SD 0.13) in MER40 and 4.5 kg/animal (SD 0.31) in MER100. Urinary N excretion and N balance did not differ between MER80, MER60, and MER40. According to contrast test, declining feed intake level from MER80 to MER40 reduced duodenal microbial crude protein flow (p < 0.001), but did not alter the EMPS (g microbial N/kg digestible organic matter intake). Yet, if scaled to N intake, EMPS increased (p < 0.049), whereas total N and faecal N excretions decreased linearly with declining intake level (p < 0.001 for both variables). At similar grass hay intake, duodenal microbial crude protein flow was 41% higher in MER100 than in MER80 steers (p < 0.001). In cattle offered poor-quality tropical forage below their MER, the very low EMPS and thus microbial protein supply aggravate the negative effects of low dietary nutrient and energy intakes in periods of feed shortage.     

施肥与刈割对内蒙古草地生态化学计量特征的影响

为明确施肥和刈割对蒙古半干旱草地四种植物化学计量特征的影响,该文于2014年8月以内蒙古半干旱草地的四种植物冷蒿(Artimesia frigida)、菊叶委陵菜(Potentilla tanacetifolia)、羊草(Aneurotepidimu chinense)、扁蓿豆(Melissitus ruthenica)为研究对象,利用方差分析及多重比较分析对照、施氮肥、割草、割草和施氮肥处理下的植物碳、氮、磷含量的差异以及不同处理下碳氮比和氮磷比的变化。结果表明:施氮肥与割草均未影响植物碳含量。施氮肥显著提高了植物氮含量(P<0.05),进而降低了碳氮比(P<0.05),提高了氮磷比(P<0.05)。割草处理后扁蓿豆的氮含量显著提高了0.18%(P<0.05),羊草的氮含量显著降低了0.13%(P<0.05),冷蒿与菊叶委陵菜的氮含量无显著变化。割草显著提高了冷蒿和菊叶委陵菜的磷含量(P<0.05),但是未影响羊草和扁蓿豆的磷含量。该研究证实了氮添加或割草会影响部分草地物种的化学计量特征,但是氮添加或割草对植物化学计量特征的影响存在种间差异。     

Influence of weight upon in vitro protein digestion in rainbow trout

Protein digestive capacity, measured by an in vitro method, was examined in individual rainbow trout of four weight groups (40–875 g; n= 14 group⁻¹), using three fish meals (FM). Differences ( P <0.05) were found in digestive capacity between groups and with FM grade used. Larger fish expressed greatest catalytic capacity.     

茯苓碳氮磷化学计量学特征

为探明茯苓的碳、氮、磷生态化学计量学特征,采集了云南省11个州、市42个居群的茯苓样本,分析了其菌核与表皮中碳(C)、氮(N)、磷(P)的化学计量特征.结果 表明:茯苓菌核中C、N、P的含量分别为40.24％-43.58％、0.176％-0.532％和0.020％-0.077％;C∶N、C∶P和N∶P的范围分别为93....     

A longitudinal study of digit ratio (2D:4D) and other finger ratios in Jamaican children

It has been hypothesised that the ratio between the length of the 2nd and 4th digits (2D:4D) is a correlate of prenatal sex steroids, and this relationship is strongest for the right hand. Furthermore, it has been suggested that 2D:4D is sexually dimorphic, the dimorphism is determined early, and 2D:4D among children is stable with growth. Here, we present the first longitudinal study of right and left hand 2D:4D. Our sample was 108 (54 males) Jamaican children. The first measurements were made in 1998 when mean age was 9.68 +/- 1.39 years, and a second set of measurements were made in 2002. We found that: (i) there was a small increase in 2D:4D with age which was lowest in the right hand; (ii) 2D:4D was sexually dimorphic, the means for males and females differed in the same direction in the 1998 and 2002 samples, and the sex difference was significant in the 1998 but not in the 2002 sample; (iii) the correlation between the 1998 and 2002 measurements of 2D:4D was high, indicating that rank order of the ratio was stable across year groups; and (iv) the rate of change in 2D:4D did not differ significantly across year groups. We conclude that 2D:4D increases slightly with age in children with the effect less marked for the right hand (i.e. the hand which is likely to show the strongest association with prenatal steroids), 2D:4D is sexually dimorphic from an early age, and the rank order of 2D:4D is stable in children. We discuss the implications of our findings for the status of 2D:4D as a correlate of prenatal sex steroids. The patterns of change in other finger ratios are also considered.     

Factors influencing nitrogen and phosphorus excretion rates of fish in a shallow lake

Summary 1. Fish excretion can be an important source of nutrients in aquatic ecosystems. Nitrogen (N) and phosphorus (P) excretion rates are influenced by many factors, including fish diet, fish growth rate and fish size. However, the relative influence of these and other factors on community‐level excretion rates of fish is unknown. 2. We used bioenergetics modeling to estimate excretion rates of eight fish species in a shallow, Minnesota (U.S.A.) lake over four months in both 2004 and 2005. Excretion rates of each species were summed for community‐level N and P excretion rates, as well as the N : P ratio of excretion. We then used a model‐selection approach to assess ability of independent variables to predict excretion rates, and to identify the most parsimonious model for predicting N : P excretion ratios and P and N excretion rates at the community scale. Predictive models were comprised of the independent variables water temperature and average fish density, fish size, fish growth rate, nutrient content of fish and nutrient content of fish diets at the community scale. 3. Fish density and nutrient content of fish diets (either N or P) were the most parsimonious models for predicting both N and P excretion rates, and explained 96% and 92% of the variance in N and P excretion, respectively. Moreover, fish density and nutrient models had 1400‐fold more support for predicting N and 21‐fold more support for predicting P excretion relative to models based on fish density only. Water temperature, fish size, fish growth rates and nutrient content of fish showed little influence on excretion rates, and none of our independent variables showed a strong relationship with N : P ratios of excretion. 4. Past work has focused on the importance of fish density as a driver of fish excretion rates on a volumetric basis. However, our results indicate that volumetric excretion rates at the community scale will also change substantially in response to changes in relative abundance of fish prey or shifts in relative dominance of planktivores, benthivores, or piscivores. Changes in community‐scale excretion rates will have subsequent influences on algal abundance, water clarity, and other ecosystem characteristics.     

南亚热带森林不同演替阶段植物与土壤中N、P的化学计量特征

选择南亚热带森林演替过程3个阶段(初期、中期和后期)的典型森林生态系统为研究对象, 在测定植物与土壤中全N、全P含量的基础上, 阐明了森林演替过程中植物与土壤的N、P化学计量特征。结果显示: 1)土壤中全N含量随演替进行而增加, 马尾松(Pinus massoniana)林(初期)、混交林(中期)和季风林(后期) 0-10 cm土层中全N含量分别为0.440、0.843和1.023 g·kg^-1; 混交林0-10 cm土层中全P的含量最为丰富, 为0.337 g·kg^-1, 马尾松林和季风林土壤全P含量分别为0.190和0.283 g·kg^-1。2)植物叶片中全N、全P的含量随演替呈减少的趋势, 但根系中全N、全P的含量都以马尾松林为最多, 混交林和季风林含量彼此相当。3)各土层中N:P随演替的进行呈现明显增加趋势, 马尾松林、混交林和季风林0-10 cm土层中N:P分别为2.3、2.5和3.6; 植物各器官中N:P随演替的进行也呈增加趋势, 且叶片和根系中的N:P相近, 马尾松林、混交林和季风林叶片中N:P分别为22.7、25.3和29.6。基于上述结果, 探讨了南亚热带森林生态系统植物与土壤中N:P特征、森林演替过程中植物与土壤中N:P变化规律以及P对南亚热带森林生态系统的限制作用。结果表明, P已经成为南亚热带森林生态系统生物生长和重要生态过程的限制因子。     

The C:N:P ratio of phytoplankton determines the relative amounts of dissolved inorganic nitrogen and phosphorus released during aerobic decomposition

Three phytoplankton assemblages, with different C:N:P ratios of 314:55:1, 103:17:1, and 57:5.5:1 (by weight), were prepared by growing lake phytoplankton in artificial media with different N:P supply ratios and then decomposed under aerobic conditions for three months.There was no net release of dissolved inorganic phosphorus (DIP) from the phytoplankton assemblage with the highest C:N:P ratio, in contrast with an abundant liberation of DIP from that with the lowest C:N:P ratio. On the other hand, there was an abundant release of dissolved inorganic nitrogen (DIN) from the phytoplankton assemblage with the highest C:N:P ratio, in contrast with little or virtually no release of DIN from those with lower C:N:P ratios. Thus, it was concluded that the C:N:P ratio of phytoplankton is an important parameter to determine the relative amounts of DIP and DIN released, when they are decomposed under aerobic conditions.Contribution from Otsu Hydrobiological Station, Kyoto University, No. 316 (Foreign Language Series).Contribution from Otsu Hydrobiological Station, Kyoto University, No. 316 (Foreign Language Series).     

The first insight into black soldier fly meal in brown trout nutrition as an environmentally sustainable fish meal replacement

Insect meals are considered among the most promising feed materials in fish nutrition due to their sustainability and possibility of fish meal replacement. The present study is the first application of full-fat black soldier fly larvae (BSFL) meal in brown trout (Salmo trutta m. fario) diets. Two experiments were performed on 240 brown trout fingerlings (average body mass 4.85 g) distributed into four groups (12 tanks for the growth performance experiment, 10 fish/tank; and 12 metabolic tanks for the digestibility test, 10 fish/tank). The experimental group design was conducted as follows: control diet, with no BSFL and 35% fish meal, and experimental diets: BSFL5 – with 5% BSFL full-fat meal and 32.5% fish meal; BSFL10 – with 10% BSFL full-fat meal and 30% fish meal; and BSFL20 – with 20% BSFL full-fat meal and 25% fish meal. No effects were recorded in the case of growth performance and feed utilization parameters. The environmental sustainability of the usage of insect meals in fish diets was proven – due to the lower fish meal inclusion, the fish-in-fish-out ratio decreased by 31% in BSFL20. In the case of the viscerosomatic index, increases in BSFL5 and BSFL20 were reported. In all experimental groups, decreases in hepatosomatic index values were observed. Crude protein digestibility decreased in BSFL5 and BSFL20, while crude fat digestibility decreased only in the BSFL20 group. The effect of including BSFL full-fat meal in a brown trout diet on serum biochemical parameters was reported. The aspartate transaminase concentration increased in BSFL10 and BSFL20, while the gamma-glutamyl transpeptidase values decreased in BSFL20. In the case of total cholesterol, higher values were observed in BSFL10 and BSFL20. The albumin content decreased in the BSFL20 group, while globulin showed the highest values in the control group. The microbiota composition was not affected by insect meal inclusion. In conclusion, the results of the present study showed the high potential of BSFL full-fat meal application of up to 20% in a brown trout diet.     

2D:4D ratios in the first 2 years of life: Stability and relation to testosterone exposure and sensitivity

The relative lengths of the 2nd and 4th digits (2D:4D) may provide an easily measurable and stable anthropometric index of prenatal androgen exposure, but no study has examined the development of 2D:4D in infancy and the potential impact of neonatal testosterone levels. We collected 2D:4D ratios from 364 children between 0 and 2 years of age. Saliva samples were collected from 236 of these children 3 months after birth and analyzed for testosterone. In addition, 259 children provided DNA samples which were genotyped for the CAG repeat polymorphism in the androgen receptor. There was substantial variability across age in 2D:4D. Sex differences were small compared to adults and did not consistently reach statistical significance. This suggests that 2D:4D may not function well as a proxy measure of prenatal testosterone exposure in infancy. In addition, the interaction of salivary T and CAG repeats predicted right hand digit ratio at 12 months and left hand digit ratio at 12 months and 24 months in males. The interaction of salivary testosterone and CAG repeat length also predicted change in left hand 2D:4D from 2 weeks to 12 months in males. This suggests that 2D:4D in adults may reflect, in part, neonatal testosterone exposure. No significant relationships were observed within females. No significant relationships were observed when salivary testosterone and CAG repeats were examined independent of each other. Results have important implications for the design and interpretation of studies which use 2D:4D as a proxy measure of prenatal testosterone exposure.     

Fish Growth in Marine Culture Systems: A Challenge for Biotechnology

Aquaculture production is constrained largely by the growth efficiency of the species being produced. Nutritional approaches have played an important part in improving this situation, but, it is argued, the room for further improvement using such established techniques is limited. Alternative ways of improving fish production by utilizing recent biotechnological advances are explored and assessed as to their potential for commercialization in the near future. Transgenic technologies promise a revolution in aquaculture, but it is considered that consumer resistance may delay the use of transgenic fish for food production. An alternative approach could be the breeding of transgenic fodder plants without the amino acid deficiencies of existing alternatives to fish meal in aquaculture diets. The use of probiotics could reduce antibiotic use on fish farms while they might also provide the basis for ``smart' diets, tailored to specific purposes by the inclusion of microorganisms. The selection and genetic engineering of nitrifying and denitrifying bacteria could also pave the way for fully enclosed, recirculating marine culture systems, which would allow control of the environmental variables that currently restrain marine fish culture. Received August 10, 1998; accepted October 8, 1998.     

Seasonal and vertical variation in the C : P ratio of suspended and settling seston of lakes

In the absence of field data it is often assumed that the C : P ratio of the seston in lakes corresponds to the ideal ratio of 106 : 1, reported by Redfield et al. (1963) for marine phytoplankton. However, we found out that in nearly all lakes studied C : P ratios deviate systematically from this value especially during periods, when phosphorus is growth limiting. Thus, during summer the sestonic C : P ratio generally exceeds 106 in the epilimnion, but decreases with depth in the hypolimnion. Possible mechanisms which may lead to these seasonal and spatial changes in the C : P ratio are discussed.     

淡水鱼类入侵种的分布、入侵途径、机制与后果

生物入侵已经成为全球面临的三大环境问题之一。鱼类入侵现象也随全球经济一体化的进程日益严重。本文综述了全球淡水鱼类入侵的现状和研究进展, 包括鱼类入侵的定义及分布、入侵途径和机制、产生的生态和社会经济影响以及预防措施等。据统计, 目前全球外来鱼类达624种, 该数量超过30年前的两倍。外来鱼类主要通过水产养殖(51%)、观赏渔业(21%)、休闲垂钓(12%)、渔业捕捞运输(7%)等多种途径被引进。入侵鱼类对本地种产生了捕食、种内种间竞争、杂交和疾病传播等负面影响, 破坏本地生态系统, 但是其正面的生态及社会经济影响也不可忽略。近20年来全球鱼类入侵日益受到重视, 相关论文发表数量翻了8倍。值得提出的是, 近10年来全球鱼类入侵风险评价系统的研究显著增加, 一些鱼类入侵模型已应用于五大洲的多个国家。我国淡水外来鱼类共计439种。然而, 我国关于鱼类入侵的研究起步较晚, 发表文献数仅占全球的3.7%, 且主要研究方向仍集中在入侵物种的分布及生物学特性等基础研究上, 缺乏对于鱼类入侵机制及风险评价预测的研究。因此, 我们建议: (1)开展全国范围的本底调查并建立数据库, 实现数据共享, 明确鱼类入侵的历史与分布现状; (2)联合多个政府部门和机构, 对鱼类入侵进行长期观测, 从整个水生生态系统的角度出发, 深入了解其入侵机制及其产生的正面和负面生态和社会经济影响; (3)加强增殖放流的科学研究和管理; (4)构建区域性外来鱼类入侵风险评价系统, 有效预测鱼类入侵活动, 评价入侵种的危害, 并为相关政府部门的决策提供科学依据。     

Eight years of internal phosphorus loading and changes in the sediment phosphorus profile of Lake Søbygaard,Denmark

During each of the first 8 years following an 80–90% reduction in external phosphorus loading of shallow, hypertrophic Lake Søbygaard, Denmark in 1982, phosphorus retention was found to be negative. Phosphorus release mainly occurred from April to October, net retention being close to zero during winter. Net internal phosphorus loading was 8 g P m^–2 y^–1 in 1983 and slowly decreased to 2 g P m^–2 y^–1 in 1990, mainly because of decreasing sediment phosphorus release during late summer and autumn. The high net release of phosphorus from Lake Søbygaard sediment is attributable to a very high phosphorus concentration and to a high transport rate in the sediment caused by bioturbation and gas ebullition. Sediment phosphorus concentration mainly decreased at a depth of 5 to 20 cm, involving sediment layers down to 23 cm. Maximum sediment phosphorus concentration, which was 11.3 mg P g^–1 dw at a depth of 14–16 cm in 1985, decreased to 8.6 mg P g^–1 dw at a depth of 16–18 cm in 1991. Phosphorus fractionation revealed that phosphorus release was accompanied by a decrease in NH₄Cl-P + NaOH-P and organic phosphorus fractions. HCl-P increased at all sediment depths. The Fe:P ratio in the superficial layer stabilized at approximately 10. Net phosphorus release can be expected to continue for another decade at the present release rate, before an Fe:P ratio of 10 will be reached in the sediment layers from which phosphorus is now being released.