Weighted Coefficient Of Variation Research Articles

Feeding protocol with live feed and inert diet to determine the ideal age/size for weaning mullet Mugil liza (Valenciennes, 1836).

The Lebranche mullet Mugil liza is a marine fish of great importance for artisanal and industrial fishing, as well as aquaculture. The use of live feeds during the larviculture phase of marine fish is a significant component of production costs. The present study evaluated the effects of the feeding transition on different larval stages of M. liza, from the combined supply of live feed (Brachionus rotundiformis + Artemia franciscana) and live + inert feed (Artemia franciscana + inert diet) until the weaning phase to only the inert diet. A total of 3240 M. liza larvae (weight 0.0133 ± 0.0062 g and length 0.793 ± 0.160 cm) were distributed among the 12 experimental units (n = 270), resulting in four groups with three replicates each. Treatment groups consisted of feed transition with A. franciscana (enriched metanauplii) to commercial inert feed starting weaning at four different larval ages: 28, 31, 34, and 37 days post hatching. Zootechnical performance indexes and intestinal histomorphometry were evaluated. Mortality, condition factor, and length variation coefficient did not show significant differences between treatments. Final weight, final length, weight gain, and length gain were significantly greater in larvae that started weaning at 31, 34, and 37 days post hatching. Weight coefficient of variation was significantly higher in larvae that started weaning at 28 days (67.51 ± 11.70) compared to 37 days (34.40 ± 7.30). In intestinal histology, villi height (180.3 ± 4.4) was significantly higher in larvae that started weaning at 37 days post hatching. Considering the evidence found in the present study, it is recommended to start weaning M. liza on the 31st day post-hatching, using a 2-day co-feeding protocol (31st and 32nd days). From the 33rd day after hatching, M. liza larvae can receive only commercial feed.

Production performance of Seurukan fish (Osteochilus sp.) with high density in recirculating system

One of the local fish (native species) that is popular with the public and has quite good market prospects in Aceh is the seurukan fish (Osteochilus sp.). Seurukan fish cultivation technology with a recirculation system needs to be developed so that its potential can be utilized optimally. This research aims to evaluate production performance and determine the optimal stocking density for rearing seurukan fish (Osteochilus sp.) in a recirculation system. This research was conducted by experimental method. The experimental design used was a completely randomized design (CRD) with three treatments of stocking density and each treatment was repeated four times. The treatments are P1 (5 fish/m2), P2 (10 fish/m2), and P3 (15 fish/m2). The rearing period for Seurukan fish lasts for 50 days. The parameters tested during the research included biological parameters consisting of survival, absolute growth rate, feed conversion ratio, weight diversity coefficient, and water quality parameters including temperature, pH and dissolved oxygen. The results showed that the seurukan fish reared at different stocking densities using a recirculation system had a significant effect on the absolute growth rate and the coefficient of variation in weight. The best treatment in this study was 5 fish/m2, with a survival rate of 100%, an absolute growth rate of 0.04 g/head/day, a feed conversion ratio of 1.63, and a coefficient of variation of weight of 17.99%.Key words: production performance; seurukan fish; recirculation system; stocking density

Effects of shelter on the welfare of juvenile Amphioctopus fangsiao: Survival, growth, behavior and physiology

Placing shelters in rearing containers is a method of environmental enrichment that can effectively improve the welfare of aquatic animals. However, a set of standard specifications for shelter use is still absent in the artificial culture of Amphioctopus fangsiao. The purpose of this study was to investigate whether shelter type significantly affects the survival, growth performance, behavior, cortisol level, and brain serotonergic system activity of juvenile A. fangsiao. Juveniles (weight 3.72 ± 0.56 g) were reared under different types of shelters for 3 weeks: no shelter (CT), PVC pipe (PP), shell (SH), and PVC corrugated plate (PC). Behavioral and physiological parameters were determined thereafter. In general, octopuses in PP treatment had the highest survival rate (83.3 ± 17.0%). The weight gain (53.40 ± 6.20%) and specific growth rate (2.03 ± 0.19% d−1) of CT octopuses were higher than those of octopuses from other treatments. CT octopuses exhibited the highest levels of aggressive behavior, cortisol, and brain serotonergic system activity, while PC octopuses showed the lowest levels of these stress-related behavioral and physiological indicators. The hepatosomatic index, coefficient of weight variation, and attachment rate did not differ significantly among treatments. Altogether, these results demonstrated for the first time that shelter type had a major impact on octopus survival, growth performance, behavioral phenotype (aggressive behavior), and stress-related physiological processes, and we suggest that using PVC pipes as shelters might be optimal for octopus rearing.

Genetic and phenotypic time trends of litter size, piglet mortality, and birth weight in pigs

IntroductionLitter size in pigs has increased steadily since 1990. Because of unfavorable genetic correlations with piglet mortality, breeding goals should include survival traits next to litter size. Unbalanced breeding programs that neglect this requirement have produced increased mortality levels, attracting negative public attention. Balanced breeding does not have this disadvantage, but the general public is largely unaware of this.MethodsWe present long-term time trends as realized in commercial breeding. The data includes (i) phenotypes of litter size, piglet birth weight, and piglet mortality, as used in routine breeding value estimation; and (ii) the genomic Best Linear Unbiased Prediction (gBLUP) estimated breeding values thus obtained. Piglet mortality (2001–2022) and birth weight (2009–2022) phenotypes were related to litter size by recording year. Estimated breeding values (EBVs) for the mortality traits were regressed on those for litter size by birth year (2012–2022).ResultsAverage litter size is very weakly correlated to the mortality (R2 ≤ 0.06) and birth weight (0.07 ≤ R2 ≤ 0.26) traits, and those correlations are unfavorable (antagonistic) within each year. However, all traits analyzed here show favorable simultaneous phenotypic and genetic trends over time: the antagonisms are neutralized by balanced breeding. Above the annual mean litter size level, farrowing and lactation mortality rates increased with increasing litter size in every year (unfavorable), but the annual intercepts and the slopes decreased from 2001 to 2022 (favorable). Average litter birth weight decreased with litter size in every year (unfavorable), but the annual intercepts increased and the slopes decreased from 2009 to 2022 (favorable). The within-litter birth weight variation coefficient increased with litter size in every year (unfavorable), but the annual intercepts decreased from 2009 to 2022 (favorable). The proportion of low birth weights (i.e.,< 0.9 kg) for a given litter size is decreasing over time, and the critical birth weight level (below which lactation mortality increases strongly) is clearly population dependent and changes over time too.DiscussionThe increases in litter size and piglet survival rates due to balanced breeding policies lead to reduced total numbers of dead piglets (i.e., per country, per year) coinciding with a certain pig production volume (i.e., with a certain total number of weaned piglets).

Evaluation of heritability and selection response of the growth in the first-generation population of gourami (Osphronemus goramy Lac.) originated from four populations

The genetic improvement program through selective breeding is one of the efforts to overcome the slow-growing constraints in gourami (Osphronemus goramy Lac.) farming. The selective breeding to improve the growth performance of gourami using the family selection method was first conducted by the formation of a base population using a diallele cross of four populations originating from Kalimantan (Borneo), Jambi, Majalengka, and Tasikmalaya. The best performing individuals were selected to produce the first generation (F1) population. This study aimed to evaluate the growth (body weight) and determine the heritability of the F1 population. Individuals selected from the base population were communally spawned using a half-sib mating with a male:female ratio of 1:2. The grow-out phase was carried out in earthen ponds with a stocking density of 5 fish/m2, 7 families out of 14 families were kept until 13 months of age. The results showed that the body weight variation coefficient ranged from 12.36-18.65% with a selection differential of 70.75 - 112.56 g. The heritability of the body weight was 0.88, with a selection response of 11.18%. These results revealed the selection progress with increased body weight in F1 population. Thus, selective breeding is effective to be continued.

Variations in the use of cemented implants for hip fracture repair in Nova Scotia, Canada

<h3>Background:</h3> Opinions differ on the use of a cemented versus uncemented implant for repair of femoral neck fractures. The purpose of this study was to compare variation in the use of cemented implants for patients with hip fracture in Nova Scotia, Canada. <h3>Methods:</h3> The study population was all patients who underwent primary emergency hip fracture arthroplasty in Nova Scotia between 2010/11 and 2019/20. We calculated 3 aggregate measures of variation across all hospitals: the extremal quotient (EQ) (ratio of the highest to the lowest rate of variation), the weighted coefficient of variation (WCV) (standard deviation divided by mean) and the systematic component of variation (SCV) (the between-surgeon variation, excluding the random component). Bootstrapped 95% confidence intervals (CIs) were computed. <h3>Results:</h3> Our study population included 3787 patients with hip fracture who underwent arthroplasty at 5 hospitals, of whom 2219 (58.6%, 95% CI 57.1%–60.2%) received cemented implants. The age- and sex-adjusted proportion of cemented cases ranged from 36.6% (95% CI 33.6%–40.0%) to 71.1% (95% CI 68.4%–73.8%). The highest EQ value was 30.3 (95% CI 0.0–80.0). The WCV ranged from 32.6 (95% CI 28.5–36.7) to 77.3 (95% CI 68.3–86.3). The SCV indicated very high between-surgeon variation at all hospitals. The WCV and SCV resulted in the same rankings for all hospitals, indicating consistency between the 2 measures. <h3>Conclusion:</h3> We found considerable variation across surgeons in the use of cemented implants for patients with hip fracture in Nova Scotia. Guidelines could help build consensus on this practice among surgeons.

Comparative analysis of the growth and development differences of children and adolescents between developed and undeveloped urban and rural areas in China.

Our study use the height and weight data of Chinese students aged 7-18 years from 1985 to 2014 to investigate the inequality and changing trend of height and weight of children and adolescents in different regions. Our study extracted data from the 1985, 2000, and 2014 Chinese National Survey on Students' Constitution and Health (CNSSCH) for a comparative analysis of the height and weight of children and adolescents aged 7-18 years in a developed city (Shanghai) and an underdeveloped province (Guizhou). The coefficients of variation (CVs) of height and weight between urban and rural boys and girls were also calculated. Since 1985, the height difference between urban and rural areas has decreased from 4.24 to 2.41 cm for boys and 3.72 to 1.99 cm for girls. The weight difference for boys and girls increased from 1.83 to 3.10kg and from 0.97 to 1.80 kg, respectively. However, from 1985 to 2014, the height and weight differences between Shanghai and Guizhou increased. In addition, from 1985 to 2014, the coefficient of height variation was greater for rural students than urban students while the coefficient of weight variation was greater for urban students than rural students. Although the difference between urban and rural areas has recently decreased, the difference between developed area (Shanghai) and underdeveloped area (Guizhou) has increased. In particular, the difference in height and weight between children in developed areas (Shanghai) and non-developed areas (Guizhou) has become larger since 1985-2014, rather than gradually decreasing over time.

Enrichment of commercial feed with new formula products on the growth, yield, and mortality of the giant gourami Osphronemus goramy

Background and objective: The giant gurami (Osphronemus goramy) is considered the most desirable freshwater species in Indonesia, mainly for food security. This study evaluated the effectiveness of newly formulated products containing water, coconut, palm sap sugar, and fungus used for enriched commercial feed and their impact on gurami sago’s (local strain) growth performance, yield, and mortality. Methods: A total of 100 g of palm sugar are cooked with 1,000 ml of freshwater for fifteen minutes at a temperature of 60 °C. Furthermore was added 2,000 ml of mature coconut water. For every 1,000 ml of a mixture of mature coconut water and palm sap sugar solution was added 2 g of Aspergillus niger (called product P1), 2 g of Rhizopus oligosporus (product P2), and 2 g of Saccharomyces cerevisiae (product P3). Commercial fish feed pellets enriched with P1, P2, and P3 were designated as P1, P2, and P3 diets. At the same time, the commercial feed added with freshwater is called P4 feed (placebo). The dosage of each product is 300 ml/kg of feed. Juvenile sago gourami (initial weight 50±2.5 g and total length 13.2±0.4 cm) were stocked in triplicate (0.5x0.5x0.5 m) in a freshwater concrete pond with a stocking density of 30 individuals. /net, an initial feeding rate of 3% per day for 90 days of the experiment. Results: The weight gain ranged from 172.43 to 215.6%, the specific growth rate increased from 0.60 and 0.75%/day. The coefficient of thermal growth increased from 27.26 to 32.83. At the same time, yield ranging from 14.88 to 21.03 g/L and mortality for 90 days of the experiment decreased from 22.22% to 6.66%. The coefficient of variation in weight was between 0.68% and 1.30%. Conclusion: Giant gourami juvenile survived and grew well in diet P2, moderate growth in diet P3, and diet P1; the lowest growth was recorded in diet P4.

Effects of Dietary Choline Levels During Pregnancy on Reproductive Performance, Plasma Metabolome and Gut Microbiota of Sows.

This study investigated the effects of dietary choline levels during gestation on reproductive performance of sows. In addition, the plasma metabolome and gut microbiota of sows was studied. A total of 260 multiparous sows were allocated to five dietary treatment groups with increasing choline concentrations (1,050, 1,450, 1,850, 2,250, and 2,650 mg/kg) in a randomized complete block design. The sows were fed experimental diets from breeding until farrowing and a common lactating diet during lactation. The results showed that the backfat (BF) gain of sows during gestation, individual birth weight for total piglets born, piglets born alive, average piglet weight at weaning increased linearly (P < 0.05), whereas the within-litter birth weight variation coefficient (CV) of piglets born alive and suckling piglet mortality decreased linearly (P < 0.05) as dietary choline level increased. A quadratic effect of dietary choline level was observed for the average daily feed intake (ADFI) of sows during lactation (P < 0.05). ADFI was maximized when the dietary choline concentration reached 1,910 mg/kg. Plasma H2O2 concentration at day 30 of gestation in the 1,050 mg/kg group was greater than that in the 1,850 and 2,650 mg/kg groups (P < 0.05). Plasma metabolomics identified 46 metabolites among the three groups. Specifically, plasma concentrations of trimethylamine-N-oxide (TMAO), dopamine, and L-proline increased while 1-methylhistidine concentration decreased as dietary choline levels increased. In addition, bacterial observed species and richness (Chao 1 and ACE) at day 110 of gestation decreased as dietary choline levels increased (P < 0.05). For the gut microbiota composition, the enhanced dietary choline level decreased the abundance of phylum Proteobacteria (P < 0.05) and increased the abundance of phylum Actinobacteria (P < 0.05) at day 30 of gestation. Compared with the 1,050 mg/kg group, the abundance of genus Terrisporobacter was less in the 1,850 mg/kg group, and genera Bacillus and Cellulomonas were greater in the 2,650 mg/kg group. In summary, increasing dietary choline levels improved the birth weight, uniformity of neonatal piglets and litter performance during lactation. This may be associated with better antioxidant capability, metabolic status, and gut microbiota of sows during gestation.

Eggs Immersion with Vitamin C on Hatching Rate, Growth and Mortality of Giant Gourami Larvae

&lt;b&gt;Background and Objective:&lt;/b&gt; The giant gourami (&lt;i&gt;Osphronemus goramy&lt;/i&gt;; Lacepede, 1801) is one of Indonesia's main freshwater fish of economic benefit for food security. This study evaluated the effects of vitamin C dosages used for immersion embryonic and larval of giant gourami. &lt;b&gt;Materials and Methods:&lt;/b&gt; The vitamin C using Ascorbic acid standard (FLUKA, Sigma-Aldrich), each weighed 50, 100, 150 and 200 mg and dissolved in 1 L of fresh borehole water is referred to as P&lt;sub&gt;2&lt;/sub&gt;, P&lt;sub&gt;3&lt;/sub&gt;, P&lt;sub&gt;4&lt;/sub&gt; and P&lt;sub&gt;5&lt;/sub&gt;. At the same time, 1 L of fresh borehole water not added with vitamin C is called P&lt;sub&gt;1&lt;/sub&gt; (Placebo). Each treatment was formulated with 5 L and poured into an incubator tank with a capacity of 10 L Then, as many as 150 eggs are incubating per experiment in each incubator tank. These larvae of each experiment were rearing for 20 days using live feed (tubifex) 40% per feed. Each treatment was three replicates. &lt;b&gt;Results:&lt;/b&gt; In this study, larval hatching rates varied from 78.59-98.22%, with the survival of endogenous feeding periods ranging between 93.08 and 99.10%. The specific growth rate increased from 11.14 and 13.38% per day. The Coefficient of thermal growth increased from 1.49-1.70. Larval mortality after exogenous feeding for 20 days of the experiment decreased from 21.11-5.56%. The Coefficient of variation in weight was between 3.19 and 14.04%. &lt;b&gt;Conclusion:&lt;/b&gt; Giant gourami eggs and larvae hatched and survived and grew well in immersion with a dose of vitamin C up to 200 mg L&lt;sup&gt;1&lt;/sup&gt;.

Stocking Density, Growth and Survival Rate of Post-Settled Juveniles of Holothuria scabra (Jaeger 1833) Reared in an Ocean-Based Floating Hapa

Ocean-based nursery system using floating hapa have proved to be the best option for raising early sandfish juveniles. However, the nursery system can be further improved by providing key information that will support their application. The present study provides information on the effect of stocking density on growth and survival of sandfish juveniles reared in floating hapa (1 x 0.5 x 1 m). Three densities were tested, 100, 200 and 400 early juveniles (5 mm; 0.093 g) per hapa net in a randomized set-up. Initial density of 100 and 200 showed significant higher growth rate and final size (0.082–0.074 g/day; 3.76–3.42 g) compared to 400 (0.045 ± 0.002 g/day; 2.11 ± 0.07 g). Moreover, at 100 and 200 densities, &gt; 95% of all juveniles attained release size (2 g) and only 74% for 400 density after 45 days of rearing. Sandfish juveniles showed negative allometric growth and their survival did not display any pattern (100 = 91%; 200 = 35%; 400 = 51.3%). The coefficient of variation for weight of juveniles showed strong positive relationship with initial density (R2 = 0.99, p = 0.039) with CV values of (100 = 48.6%; 200 = 49.8%; 400 = 50.1%). It is therefore concluded that, 100 stocking density should be opted for optimum results, however, 200 can also be considered provided that, the survival is improved. &#x0D; Keywords: Sea cucumber; Ocean-based Nursery; Stocking density; Survival rate; Growth rate

Frozen zooplankton is efficient as natural food during pirarucu Arapaima gigas weaning

The commercial production of carnivorous fish depends on the feed training that can be made through the direct transition from natural food to inert food. As using live natural food requires care in production, alternative methods of using live food are necessary, such as freezing. Thus, the aim of this study was to evaluate the use of frozen zooplankton as an initial diet in the feed training of pirarucu Arapaima gigas juveniles. Three hundred and twenty pirarucu juveniles (13.94 ± 4.99 g) were submitted to weaning with two different initial diets (treatments): live zooplankton and frozen zooplankton. The co-feeding period was 12 days, with a progressive increase in the amount of feed offered and a decrease in zooplankton every three days. At the end of the training, all fish were ready to be fed with commercial feed. There was no mortality in the experiment and no significant differences (p > 0.05) for weight, length, weight variation coefficient, specific growth rate, intestinal coefficient, hepatosomatic index, muscle layer thickness and height of the branched folds intestinal mucosa, moisture, crude protein and carcass energy for fish that received live or frozen zooplankton as a starter. Isotopic values of δ15 N and δ13C in the fish's muscle were similar (p > 0.05), reinforcing no feeding preference of the fish between the live or frozen zooplankton. The water quality was not influenced by the use of initial diet (p > 0.05). The frozen zooplankton can be used as initial food for pirarucu juveniles feed training, without impairing fish growth and survival.

Experimental study for the establishment of a chemotherapy-induced ovarian insufficiency model in rats by using cyclophosphamide combined with busulfan

With an improvement in the survival rate of cancer patients, chemotherapy-induced premature ovarian insufficiency (POI) is increasingly affecting the quality of life of female patients. Currently, there are many relevant studies using mice as an animal model. However, a large coefficient of variation for weight in mice is not appropriate for endocrine-related studies, compared with rats; therefore, it is necessary to identify an appropriate experimental model in rats. In this study, cyclophosphamide combined with busulfan was used to establish an animal model. We compared several common modeling methods using chemotherapeutic drugs, cisplatin, cyclophosphamide, and 4-vinylcyclohexene diepoxide (VCD), and we found that the combination of cyclophosphamide and busulfan was more effective in establishing a POI model in rats with few side effects by analyzing general physical conditions, pathological tissue sections of heart, liver, lung, spleen, kidney, uterus, and ovary, serum hormone levels, and follicle counts; thus, providing a more reliable model basis for subsequent studies.

Effect of size grading on the growth of pirarucu Arapaima gigas reared in earthen ponds

Size grading is a common management practice in fish farming to minimize growth variability. Such practice has not been established for pirarucu Arapaima gigas. Therefore, the present study assessed the effect of size grading on the growth of pirarucu. Juvenile pirarucu were divided into three groups: ungraded fish (U: mean initial weight 1.12 kg), small fish (S: mean initial weight 0.81 kg), and large fish (L: mean initial weight 1.36 kg), and reared for 129 days (phase I) and 158 additional days (phase II), consecutively. No significant difference was observed in the final length, specific growth rate, biomass, survival and feed conversion rate between fish groups. Ungraded fish presented a greater decrease in the coefficient of variation for weight in phase I than in phase II. Size sorting resulted in significantly higher growth after 287 days of farming in the L-graded fish (9.49 kg, final weight), followed by the ungraded group (8.80 kg) and S-graded group (8.01 kg). However, the mean weight of pooled S- and L-graded fish was similar to the ungraded fish group in phase I and phase II, indicating that grading did not improve the general performance of pirarucu in captivity.

Encapsulation of Black Seed Oil in Alginate Beads as a pH-Sensitive Carrier for Intestine-Targeted Drug Delivery: In Vitro, In Vivo and Ex Vivo Study.

Black seed oil (BSO) has been used for various therapeutic purposes around the world since ancient eras. It is one of the most prominent oils used in nutraceutical formulations and daily consumption for its significant therapeutic value is common phenomena. The main aim of this study was to develop alginate-BSO beads as a controlled release system designed to control drug release in the gastrointestinal tract (GIT). Electrospray technology facilitates formulation of small and uniform beads with higher diffusion and swelling rates resulting in process performance improvement. The effect of different formulation and process variables was evaluated on the internal and external bead morphology, size, shape, encapsulation efficiency, swelling rate, in vitro drug release, release mechanism, ex vivo mucoadhesive strength and gastrointestinal tract qualitative and quantitative distribution. All the formulated beads showed small sizes of 0.58 ± 0.01 mm (F8) and spherical shape of 0.03 ± 0.00 mm. The coefficient of weight variation (%) ranged from 1.37 (F8) to 3.93 (F5) ng. All formulations (F1–F9) were studied in vitro for release characteristics and swelling behaviour, then the release data were fitted to various equations to determine the exponent (ns), swelling kinetic constant (ks), swelling rate (%/h), correlation coefficient (r2) and release kinetic mechanism. The oil encapsulation efficiency was almost complete at 90.13% ± 0.93% in dried beads. The maximum bead swelling rate showed 982.23 (F8, r2 = 0.996) in pH 6.8 and the drug release exceeded 90% in simulated gastrointestinal fluid (pH 6.8). Moreover, the beads were well distributed throughout various parts of the intestine. This designed formulation could possibly be advantageous in terms of increased bioavailability and targeted drug delivery to the intestine region and thus may find applications in some diseases like irritable bowel syndrome.

Effects of stocking density on the survival, growth and physical injury of Marsupenaeus japonicus juveniles in a flowing water aquaculture system

Stocking density is a biotic factor affecting the production of cultivated animals in aquaculture. Herein, a rearing trial was conducted to investigate the impact of stocking density on the survival, growth performance and physical injury of Marsupenaeus japonicus juveniles in a flowing water aquaculture system. Five stocking densities were examined in this study, that is, 10, 20, 40, 80 and 160 individuals/m2. Throughout the experiment, ammonia nitrogen and nitrite concentrations ranged from 0.02 ± 0.006 mg/L to 0.08 ± 0.035 mg/L and 0.002 ± 0.001 mg/L to 0.076 ± 0.021 mg/L respectively. The survival rate, specific growth rate (SGR), weight gain (WG), absolute growth rate (AGR) and coefficient of variation for weight (CV) across the stocking densities ranged from 90.38 ± 3.20% to 94.33 ± 4.73%, 1.42 ± 0.16%/day to 1.53 ± 0.05%/day, 1.09 ± 0.19 g to 1.15 ± 0.16 g, 0.018 ± 0.003 g/day to 0.019 ± 0.004 g/day and 16.21 ± 5.78% to 35.09 ± 10.68% respectively. Within the investigated densities, the survival rate and the abovementioned growth parameters were not significantly (p > .05) affected by the stocking density, consequently, a higher stocking density resulted in a significantly (p < .05) greater final biomass. The results regarding physical injury showed that the antennal breakage rate displayed a tendency of a positive correlation with the stocking density. Overall, the current study provides basic data for establishing a viable intensive farming system for M. japonicus and a promising indicator for easily assessing the crowding stress status of M. japonicus.

Investigation on vibration induced segregation behaviour of crushed GMZ bentonite pellet mixtures

Mixture of high-density bentonite pellets are considered as a potential buffer/backfill material for high-level radioactive wastes (HLW) repository. One of the outstanding problems of this material is the particle segregation induced by vibration during transportation and emplacement. In this work, the vibration-induced segregation behavior of crushed GMZ (Gaomiaozi) bentonite pellet mixtures with different size distributions was experimentally investigated using a cylindrical container under vertical vibrations. The degree of segregation was evaluated by a weighted coefficient of variation (WCV) reflecting the changes in particle size distribution before and after vibration. Results show that generally the WCV increases with decreases of particle size ratio, the mass fraction of the fine size class and the number of size classes of the mixture. The influences of particle size ratio and distribution were interpreted by two dominant mechanisms including percolation and convection, and could be incorporated into a particle characteristic index (PCI). Further analysis shows that the WCV monotonously increases with the increase of PCI and the relationship between them can be well described using a sigmoid function. Finally, based on the analyses of the experimental results, strategies for reducing segregation were proposed.

Effects of environmental enrichment on the welfare of juvenile black rockfish Sebastes schlegelii: Growth, behavior and physiology

Environmental enrichment is a promising way to enhance fish welfare in aquaculture. However, the observed effects of enrichment on fish growth, behavior and physiology vary widely among studies, and few studies have focused on the quantification of enrichment. The present study aimed to investigate whether enrichment type and level significantly affect the growth performance, aggressive behavior, cortisol level and brain monoaminergic activities of juveniles of the black rockfish Sebastes schlegelii. Juveniles were reared for eight weeks under different combinations of enrichment type and enrichment level: no environmental enrichment (C), low-level plant enrichment (PL), medium-level plant enrichment (PM), high-level plant enrichment (PH), low-level structure enrichment (SL), medium-level structure enrichment (SM) and high-level structure enrichment (SH). Subsequently, behavioral and physiological parameters were determined. In general, the growth performance, feed intake and food conversion efficiency of C, PM, PH and SL fish were relatively higher than those of fish from the other treatments. Low-level plant treatment produced the highest levels of aggressive behavior, cortisol and brain serotonergic system activity, whereas the medium- and high-level structure treatments yielded the lowest levels of these stress-related behavioral and physiological indicators. C fish had significantly higher stress levels than PM, PH and SL fish. No significant difference among treatments was observed in the condition factor, coefficient of weight variation, locomotor activity, growth hormone level or brain dopaminergic system activity. Taken together, these results provide the first evidence to show that the type and level of environmental enrichment have interaction effects on fish growth performance, behavioral phenotype (especially aggressive behavior) and stress-related physiological processes. Since the control fish had significantly higher stress levels than the fish exposed to medium- and high-level plant enrichment and low-level structure enrichment, we suggest that enriching approximately 50% basal area coverage with objects might be optimal for enhancing fish welfare. Moreover, a possible conceptual model is presented to interpret the effects of enrichment on fish welfare.

Effects of stocking density on stress response, innate immune parameters, and welfare of turbot (Scophthalmus maximus)

This experiment was conducted to investigate the growth performance, stress and immune responses, and welfare of juvenile turbot (Scophthalmus maximus) under three different densities (initial density 9.3, 13.6, and 19.1 kg m−2) for 120 days in a recirculating aquaculture system. Turbot were measured every 20 days to evaluate growth biometrically and sampled every month to measure biochemical parameters and mRNA levels of some stress-related genes. No significant differences were detected in the parameters and gene expression among density groups until the final sampling, except Fulton’s condition factor, lysozyme, immunoglobulin M, and complement C3. At the end of the experiment (final density 26.11, 38.22, and 52.25 kg m−2), turbot reared in the high-density (HD) group had lower body mass increase, specific growth rate, and Fulton’s condition factor, as well as higher feed conversion ratio and coefficient of variation for weight than those reared in the low-density (LD) group (P < 0.05). Fish in the HD group had higher serum cortisol, glucose, lactate, and cholesterol levels than fish in the other groups, whereas they had lower lysozyme, immunoglobulin M, and complement C3 and C4 contents (P < 0.05). Fish reared in the HD group also had higher serum chloride and osmolality levels and higher sodium-potassium adenosine triphosphatase (Na+,K+-ATPase) activity and higher Na+,K+-ATPase gene expression levels in gills compared to the other groups (P < 0.05). The mRNA levels of cytochrome P450 1A (CYP1A) and heat-shock proteins 70 and 90 (HSP70 and HSP90) were significantly upregulated, whereas glutathione S-transferase (GST) mRNA levels were significantly downregulated in the head kidney of fish in the HD group relative to fish in the other groups at the end of this trial (P < 0.05). These results indicated that overly high stocking (~50 kg m−2) density can negatively affect the growth performance, serum biochemical parameters, osmolality levels, stress-related gene expression, and overall welfare of turbot.

Macrophyte detritus as nursery diets for juvenile sea cucumber Stichopus cf. horrens

Effective culturing and restocking of any commercial holothurian are dependent on understanding the biology and ecology of the species throughout its life history. Inherent differences between species require distinct strategies in larval and juvenile rearing. This study evaluated the effect of macroalgal and seagrass detritus as supplemental food on growth, feeding and sheltering behaviour, and biochemical composition of cultured Stichopus cf. horrens juveniles (2.6–3.8 g) under nursery rearing conditions. The addition of detritus to sediments did not significantly affect juvenile growth and body composition when compared to a biofilm-only control. Average specific growth rates were positive throughout the experiment (1.58%–7.88% per day), however size variability, feeding rate, and sheltering behaviour differed significantly. Juveniles in treatments with macroalgal detritus had the highest coefficient of variation in weight (40%–51%) and a propensity to avoid sheltering near the sediments. This is presumably due to anoxic sediment conditions that developed in the macroalgal treatment over time. Juveniles in detritus treatments exhibited lower faecal production rates at the beginning of the experiment and after 75 days without significant differences in growth, suggesting the availability of high-quality food in these treatments. This study provides key insights on husbandry conditions highly relevant to further develop S. cf. horrens aquaculture.