Dissolved oxygen(DO)is one of most important factors which affect wide range physiologic features of including immune responses and intestinal bacterial community.However,the underlying mechanisms remain enigmatic.To ...Dissolved oxygen(DO)is one of most important factors which affect wide range physiologic features of including immune responses and intestinal bacterial community.However,the underlying mechanisms remain enigmatic.To address this question,the intestinal bacterial community compositions and the immune features of Atlantic salmon(Salmo salar)grown in recirculating aquaculture systems(RAS)were characterized.Fish were reared under different DO saturation levels,e.g.,200% saturation named high group(H),100%saturation named control group(CK),and 60%saturation named lower group(L).Large variations in the operational taxonomic units(OTUs)frequency distribution for the intestinal bacterial community of Atlantic salmon were observed.The intestinal bacterial community of all groups was dominated mainly by three phyla,e.g.,Proteobacteria.Firmicutes,and Bacteroidetes.Interestingly,Acinetobacter baumannii,an opportunistic pathogen of salmon was increased significantly in L group.We further monitored the immunity features of fish under different DO levels.The results show that leucocyte number,cortisol level,the expressions of interleukin-1β(IL-1β),Toll-like receptor 4(TLR4),and nucleotide-binding oligomerization domain like protein 2(NOD2)were higher at significant levels in the L group than those in the other two groups.TLR4 and NOD2 are usually related with the bacterial infections;therefore,it is reasonable to believe that the stronger immune responses observed in the L group might be related with the higher abundance of A.baumannii in the inte stine of Atlantic salmon.Overall,these findings demonstrated that low DO level may induce stronger immunity responses in Atlantic salmon.展开更多
The contamination of Atlantic salmon with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has impeded the development of the cold-chain food industry and posed possible risks to the population.Electron beam...The contamination of Atlantic salmon with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has impeded the development of the cold-chain food industry and posed possible risks to the population.Electron beam(E-beam)irradiation under 2,4,7,and 10 kGy can effectively inactivate SARS-CoV-2 in cold-chain seafood.However,there are few statistics about the quality changes of salmon exposed to these irradiation dosages.This work demonstrated that E-beam irradiation at dosages capable of killing SARS-CoV-2 induced lipid oxidation,decreased vitamin A content,and increased some amino acids and ash content.In addition,irradiation altered the textural features of salmon,such as its hardness,resilience,cohesiveness,and chewiness.The irradiation considerably affected the L*,a*,and b*values of salmon,with the L*value increasing and a*,b*values decreasing.There was no significant difference in the sensory evaluation of control and irradiated salmon.It was shown that irradiation with 2−7 kGy E-beam did not significantly degrade quality.The inactivation of SARS-CoV-2 in salmon is advised at a dose of 2 kGy.展开更多
Atlantic salmon Salmo salar were reared at four stocking densities--high density D1 (final density -39 kg/m^3), medium densities DE (-29 kg/m^3) and D3 (~19 kg/m^3), and low density D4 (-12 kg/m^3)- for 40 day...Atlantic salmon Salmo salar were reared at four stocking densities--high density D1 (final density -39 kg/m^3), medium densities DE (-29 kg/m^3) and D3 (~19 kg/m^3), and low density D4 (-12 kg/m^3)- for 40 days to investigate the effect of stocking density on their growth performance, body composition and energy budgets. Stocking density did not significantly affect specific growth rate in terms of weight (SGRw) but did affect specific growth rate in terms of energy (SGRe). Stocking density significantly influenced the ration level (RLw and RLe), feed conversion ratio (FCRw and FCRe) and apparent digestibility rate (ADR). Ration level and FCRw tended to increase with increasing density. Fish at the highest density D~ and lowest density D4 showed lower FCRe and higher ADR than at medium densities. Stocking density significantly affected protein and energy contents of the body but did not affect its moisture, lipid, or ash contents. The expenditure of energy for metabolism in the low-density and high-density groups was lower than that in the medium-density groups. Stocking density affected energy utilization from the feces but had no effect on excretion rate. The greater energy allocation to growth at high density and low density may be attributed to reduced metabolic rate and increased apparent digestibility rate. These findings provide information that will assist selection of suitable stocking densities in the Atlantic-salmon-farming industry.展开更多
The present study sampled the intestinal content of healthy and unhealthy Atlantic salmon (Salmo salar L.), the ambient water of unhealthy fish, and the biofilter material in the recirculating aquaculture system (...The present study sampled the intestinal content of healthy and unhealthy Atlantic salmon (Salmo salar L.), the ambient water of unhealthy fish, and the biofilter material in the recirculating aquaculture system (RAS) to understand differences in the intestinal microbiota. The V4--V5 regions of the prokaryotic 16S rRNA genes in the samples were analyzed by MiSeq high-throughput sequencing. The fish were adults with no differences in body length or weight. Representative members of the intestinal microbiota were identified. The intestinal microbiota of the healthy fish included Proteobacteria (44.33%), Actinobacteria (17.89%), Baeteroidetes (15.25%), and Firmicutes (9.11%), among which the families Mierococcaceae and Oxalobacteraceae and genera Sphingomonas, Streptomyces, Pedobacter, Janthinobacterium, Burkholderia, and Balneimonas were most abundant. Proteobacteria (70.46%), Bacteroidetes (7.59%), and Firmicutes (7.55%) dominated the microbiota of unhealthy fish, and Chloroflexi (2.71%), and Aliivibrio and Vibrio as well as genera in the family Aeromonadaceae were most strongly represented. Overall, the intestinal hindgut microbiota differed between healthy and unhealthy fish. This study offers a useful tool for monitoring the health status of fish and for screening the utility of probiotics by studying the intestinal microbiota.展开更多
Although it has been hypothesized that a predictable feeding regime in animals allows physiological variables to be adjusted to maximize nutrient utilization and,hence,better growth performance,the assumption has rare...Although it has been hypothesized that a predictable feeding regime in animals allows physiological variables to be adjusted to maximize nutrient utilization and,hence,better growth performance,the assumption has rarely been tested.This study compares the effects of time-restricted versus free access self-feeding on the growth,feeding behavior and daily digestive enzyme rhythms of Atlantic salmon(Salmo salar).In an experiment that lasted 6 weeks,fish(109.9 g) were divided into two groups:group 1 had free access to a self-feeder(FA);group 2 received three meals per day(2 h per meal) at dawn,midday and dusk via a time-restricted self-feeder(TR).At the end of the experiment,the fish were sampled every 3 h over a24-h period.The results showed that the TR fish quickly synchronized their feeding behavior to the feeding window and their blood glucose showed a significant postprandial increase,while FA fish displayed no statistically significant rhythms(P>0.05).Pepsin activity of TR fish also showed a significant daily rhythm(P<0.05) with the acrophase at the second feed and a decrease over the next 12 h.Average daily trypsin,lipase and amylase levels of FA fish were significantly lower than those of TR fish(P<0.01);however,the growth performance of both groups was similar(P>0.05).In conclusion,the study failed to confirm a link between the entrainment of daily digestive enzyme profiles and growth performance,with the TR group showing comparatively poor blood glucose regulation.展开更多
The effects of different feeds and feeding regimes on growth performance, flesh quality and fecal viscosity of Atlantic salmon (Salmo salar L.) in recirculating aquaculture systems (R.AS) were investigated. Fish ...The effects of different feeds and feeding regimes on growth performance, flesh quality and fecal viscosity of Atlantic salmon (Salmo salar L.) in recirculating aquaculture systems (R.AS) were investigated. Fish (initial body weight of 1677 g+ 157 g) were fed with four commercial feeds (Nosan salmon-NS, Aller gold-AG, Skretting salmon-SS and Hart ye-HY) in two feeding regimes (80% and 100% satiation) for 78 d. The results showed that salmon specific growth ratio (SGR) and weight gain ratio (WGR) were significantly affected by feed type and feeding regime (P〈0.05). Feed conversion ratio (FCR) varied between 0.93 and 3.40, which was significantly affected by feed type (P〈0.05), and slightly improved with increased satiation degree. The activities of digestive enzymes including protease, lipase and amylase were also significantly affected by feed type and feeding regime (P〈0.05), increasing with satiation degree. Flesh qualities for vitamin E, hydroxyproline (HYP), liquid loss and muscle pH among all groups showed significant differences (P〈0.05), ranging from 26.67 to 29.67, while no obvious difference was found in flesh color. Fecal viscosity for different treatments showed no significant difference, though improvement was found in 100% satiation group. From present experiment, it was concluded that both feed type and feeding regime can affect the important quality attributes of Atlantic salmon.展开更多
The combined effects of feeding rate(0.8%,1.0%,and 1.2%initial body weight/day),feeding frequency(two,three,and four times/day) and stocking density(10,15,and 20 kg/m3) in recirculating aquaculture systems(RAS) on gro...The combined effects of feeding rate(0.8%,1.0%,and 1.2%initial body weight/day),feeding frequency(two,three,and four times/day) and stocking density(10,15,and 20 kg/m3) in recirculating aquaculture systems(RAS) on growth performance,digestion and waste generation of Atlantic salmon(Salmo salar L.) were investigated in an 8-week orthogonal experiment(L9(3)3) with a constant daily water renewal at 7.50%of total volume.No mortality occurred during the experimental period.Feed conversion ratio(FCR) varied from 0.90 to 1.13 and specific growth rate(SGR) ranged from 0.48%to 0.69%/day.SGR,thermal growth coefficient(TGC) and FCR were not significantly(P>0.05) affected by the three factors,while net protein utilization(NPU) was significantly(P<0.05) affected.Apparent digestibility coefficients(ADC) of dry matter in the present study were in the range 66.12%-73.55%.ADC in protein,lipid and energy were statistically different among all treatments and in the range of 90.07%-93.67%,81.54%-89.15%,and67.55%-71.87%,respectively.The proportion of mean total ammonia nitrogen excreted ranged from 1.37%to 1.64%of feed nitrogen at steady state,and the concentration of nitrogenous and phosphorus compounds were differently correlated to the three factors.The results will provide valuable reference data for culture management decisions in the Atlantic salmon farming industry.展开更多
The timing of river entry in the Atlantic salmon is known to depend on genetic, demographic and environmental factors, but little is known about the relative magnitude of among population and among year variation and ...The timing of river entry in the Atlantic salmon is known to depend on genetic, demographic and environmental factors, but little is known about the relative magnitude of among population and among year variation and covariation in this respect in natural state Atlantic salmon rives. To investigate this, variability in the timing of river entry in three historical Finnish Atlantic salmon populations were analyzed using salmon trap data collected during 1870- 1902. The analyses reveled that 1 ) the timing of river entry differed substantially and consistently among the rivers, and that 2) variation among the rivers was much larger than variation among years. Annual variations were not explained by regional environmental conditions, whereas in one river the timing of the local flood peak was a significant predictor of the timing of river entry. Differences in the timing of salmon entry to geographically closely situated rivers suggests that a regionally fixed opening date for coastal fisheries might not be the best management strategy as it may lead to uneven exploitation of salmon populations from different rivers [ Current Zoology 55 (5) : 342 - 349, 2009] .展开更多
The aim of this study was to evaluate the effects of pumping height and repeated pumping on the generalized stress response and gross injuries in harvest sized Atlantic salmon. Fish pumped from a net pen at either hig...The aim of this study was to evaluate the effects of pumping height and repeated pumping on the generalized stress response and gross injuries in harvest sized Atlantic salmon. Fish pumped from a net pen at either high (5.2 m) or low (3.6 m) pumping heights showed an elevated, but not severe physiological stress response (pH, pCO<sub>2</sub>, lactate, potassium, haematocrit, and sodium) compared to fish netted (not pumped), while effects of different pumping heights were overall not demonstrated. Repeated pumping (either 3 or 6 times) also caused an increase in stress response (pH, pCO<sub>2</sub>, pO<sub>2</sub>, lactate, potassium and sodium) compared to control fish, and a positive dose-response relationship was found for lactate. No fish died as a result of pumping, nor were injuries observed that could exclusively be attributed to pumping. In conclusion, although elevated from the control groups, the stress response following increasing pumping height and repeated pumping as conducted in these experiments were not indicative of causing severe stress or injuries.展开更多
Atlantic salmon(Salmo salar)fed a carbohydrate-rich diet exhibit suboptimal growth performance,along with other metabolic disturbances.It is well known that gut microbes play a pivotal role in influencing metabolism o...Atlantic salmon(Salmo salar)fed a carbohydrate-rich diet exhibit suboptimal growth performance,along with other metabolic disturbances.It is well known that gut microbes play a pivotal role in influencing metabolism of the host,and these microbes can be modified by the diet.The main goal of the present study was to determine the effect of feeding graded levels of digestible carbohydrates to Atlantic salmon on the distal intestine digesta microbiota at 3 sampling times(i.e.,weeks 4,8 and 12),during a 12-week trial.A low carbohydrate-to-high protein diet(LC/HP,0%wheat starch),a medium carbohydrate-tomedium protein diet(MC/MP,15%wheat starch)or a high carbohydrate-to-low protein diet(HC/LP,30%wheat starch)was fed to triplicate fish tanks(27 to 28 fish per tank).We performed an in-depth characterization of the distal intestine digesta microbiota.Further,growth parameters,liver histology and the expression of genes involved in hepatic neolipogenesis in fish were measured.Fish fed a HC/LP diet showed greater hepatosomatic and viscerosomatic indexes(P=0.026 and P=0.018,respectively),lower final weight(P=0.005),weight gain(P=0.003),feed efficiency(P=0.033)and growth rate(P=0.003)compared with fish fed the LC/HP diet.Further,feeding salmon a high digestible carbohydrate diet caused greater lipid vacuolization,steatosis index(P=0.007)and expression of fatty acid synthase(fas)and delta-6 fatty acyl desaturase(d6fad)(P=0.001 and P=0.001,respectively)in the liver compared with fish fed the LC/HP diet.Although,the major impact of feeding a carbohydrate-rich diet to Atlantic salmon in beta diversity of distal intestine digesta microbiota was observed at week 4(HC/LP vs MC/MP and HC/LP vs LC/HP;P=0.007 and P=0.008,respectively)and week 8(HC/LP vs MC/MP;P=0.04),no differences between experimental groups were detected after 12 weeks of feeding.Finally,at the end of the trial,there was a negative correlation between lactic acid bacteria(LAB)members,including Leuconostoc and Lactobacillus,with hepatic steatosis level,the hepatosomatic and viscerosomatic indexes as well as the expression of fas and d6fad.Weissella showed negative correlation with hepatic steatosis level and the hepatosomatic index.Finally,further research to explore the potential use of LAB as probiotics to improve liver health in carnivorous fish fed fatty liver-induced diet is warranted.展开更多
Electronic tags are widespread tools for studying aquatic animal behavior;however,tags risk behavioral manipulation and negative welfare outcomes.During an experiment to test behavioral differences of Atlantic salmon ...Electronic tags are widespread tools for studying aquatic animal behavior;however,tags risk behavioral manipulation and negative welfare outcomes.During an experiment to test behavioral differences of Atlantic salmon Sal mo salar in different aquaculture cage types,including ones expected to elicit deeper swimming behavior,we found negative tagging effects depending on whether cages were depth-modified.In the experiment,data storage tags implanted in Atlantic salmon tracked their depth behavior and survival in unmodified sea-cages and depth-modified seacages that forced fish below or into a narrow seawater-or freshwater-filled snorkel tube from a 4 m net roof to the surface.All tagged individuals survived in unmodified cages;however,survival was reduced to 62%in depth-modified cages.Survivors in depth-modified cages spent considerably less time above 4 m than those in unmodified cages,and dying individuals in depth-modified cages tended to position in progressively shallower water.The maximum depth that fish in our study could attain neutral buoyancy was estimated at 22 m in seawater.We calculated that the added tag weight in water reduced this to 8 m,and subtracting the tag volume from the peritoneal cavity where the swim bladder reinflates reduced this further to 4 m.We conclude that the internal tag weight and volume affected buoyancy regulation as well as the survival and behavior of tagged fish.Future tagging studies on aquatic animals should carefully consider the buoyancy-related consequences of internal tags with excess weight in water,and the inclusion of data from dying tagged animals when estimating normal depth behaviors.展开更多
Road salts are frequently used for deicing of roads in the Nordic countries. During snow-melt, the road run-off containing high concentrations of road salt and various metals such as Cu remobilized from sand, silt and...Road salts are frequently used for deicing of roads in the Nordic countries. During snow-melt, the road run-off containing high concentrations of road salt and various metals such as Cu remobilized from sand, silt and dust may negatively influence organisms in downstream receiving water bodies. The present work focuses on the impact of road salt(NaCl) and Cu, separately and in mixtures on Atlantic salmon alevins from hatching till swim-up. The results showed that high road salt concentrations could induce a series of negative effects in alevins such as reduced growth, deformities, delayed swim-up and mortality. For alevins exposed to all tested road salt concentrations(100–1000 mg/L),mortality was significantly higher compared to control. In exposure to Cu solutions(5–20 μg Cu/L), no effects on growth, morphology, swim-up or mortality of alevins compared to control were observed. In mixture solutions(road salt and Cu), ultrafiltration of the exposure water demonstrated that only 20%–40% of Cu was present as positively charged low molecular mass(LMM) Cu species assumed to be bioavailable. When exposed to road salt and Cu mixtures, negative effects in alevins such as reduced growth, deformities,delayed swim-up and mortality were observed. The overall results indicated that the road salt application could seriously affect sensitive life stages of Atlantic salmon, and application of road salt should be avoided during the late winter–early spring period.展开更多
基金Supported by the Shandong Province Key Research and Invention Program(No.2017CXGC010K)the China Agriculture Research System(No.CARS-47)+7 种基金the National Key Research and Development Program(No.2018YFD0901204)the National Infrastructure of Fishery Germplasm Resource(No.2019DKA30470)the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018SDKJ0502-2)the National Natural Science Foundation of China(Nos.31872606,31572657,U1701233,31402283,31802319)the Department of Agriculture and Rural Areas of Guangdong Province(No.KA1911101)the Natural Science Foundation of Shandong Province(No.ZR2018BC053)the Agricultural Application Technology Innovation Project of Shandong Province in 2018/2019(No.SD2019YY011)the Shandong Province Major Scientific and Technological Innovation Projects(No.2019JZZY020710)。
文摘Dissolved oxygen(DO)is one of most important factors which affect wide range physiologic features of including immune responses and intestinal bacterial community.However,the underlying mechanisms remain enigmatic.To address this question,the intestinal bacterial community compositions and the immune features of Atlantic salmon(Salmo salar)grown in recirculating aquaculture systems(RAS)were characterized.Fish were reared under different DO saturation levels,e.g.,200% saturation named high group(H),100%saturation named control group(CK),and 60%saturation named lower group(L).Large variations in the operational taxonomic units(OTUs)frequency distribution for the intestinal bacterial community of Atlantic salmon were observed.The intestinal bacterial community of all groups was dominated mainly by three phyla,e.g.,Proteobacteria.Firmicutes,and Bacteroidetes.Interestingly,Acinetobacter baumannii,an opportunistic pathogen of salmon was increased significantly in L group.We further monitored the immunity features of fish under different DO levels.The results show that leucocyte number,cortisol level,the expressions of interleukin-1β(IL-1β),Toll-like receptor 4(TLR4),and nucleotide-binding oligomerization domain like protein 2(NOD2)were higher at significant levels in the L group than those in the other two groups.TLR4 and NOD2 are usually related with the bacterial infections;therefore,it is reasonable to believe that the stronger immune responses observed in the L group might be related with the higher abundance of A.baumannii in the inte stine of Atlantic salmon.Overall,these findings demonstrated that low DO level may induce stronger immunity responses in Atlantic salmon.
基金the grants from Hangzhou Global Scientific and Technological Innovation Center of Zhejiang University(KC2021ZY0B0003).
文摘The contamination of Atlantic salmon with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has impeded the development of the cold-chain food industry and posed possible risks to the population.Electron beam(E-beam)irradiation under 2,4,7,and 10 kGy can effectively inactivate SARS-CoV-2 in cold-chain seafood.However,there are few statistics about the quality changes of salmon exposed to these irradiation dosages.This work demonstrated that E-beam irradiation at dosages capable of killing SARS-CoV-2 induced lipid oxidation,decreased vitamin A content,and increased some amino acids and ash content.In addition,irradiation altered the textural features of salmon,such as its hardness,resilience,cohesiveness,and chewiness.The irradiation considerably affected the L*,a*,and b*values of salmon,with the L*value increasing and a*,b*values decreasing.There was no significant difference in the sensory evaluation of control and irradiated salmon.It was shown that irradiation with 2−7 kGy E-beam did not significantly degrade quality.The inactivation of SARS-CoV-2 in salmon is advised at a dose of 2 kGy.
基金Supported by the National Natural Science Foundation of China(No.31240012)the Earmarked Fund for Modern Agro-industry Technology Research System+2 种基金the Special Foundation for Postdoctoral Innovative Projects of Shandong Province(No.201101009)the National Key Technology R&D Program of China(No.2011BAD13B04)The Key Laboratory of Mariculture(KLM),Ministry of Education,Ocean University of China(OUC)
文摘Atlantic salmon Salmo salar were reared at four stocking densities--high density D1 (final density -39 kg/m^3), medium densities DE (-29 kg/m^3) and D3 (~19 kg/m^3), and low density D4 (-12 kg/m^3)- for 40 days to investigate the effect of stocking density on their growth performance, body composition and energy budgets. Stocking density did not significantly affect specific growth rate in terms of weight (SGRw) but did affect specific growth rate in terms of energy (SGRe). Stocking density significantly influenced the ration level (RLw and RLe), feed conversion ratio (FCRw and FCRe) and apparent digestibility rate (ADR). Ration level and FCRw tended to increase with increasing density. Fish at the highest density D~ and lowest density D4 showed lower FCRe and higher ADR than at medium densities. Stocking density significantly affected protein and energy contents of the body but did not affect its moisture, lipid, or ash contents. The expenditure of energy for metabolism in the low-density and high-density groups was lower than that in the medium-density groups. Stocking density affected energy utilization from the feces but had no effect on excretion rate. The greater energy allocation to growth at high density and low density may be attributed to reduced metabolic rate and increased apparent digestibility rate. These findings provide information that will assist selection of suitable stocking densities in the Atlantic-salmon-farming industry.
基金Supported by the National Natural Science Foundation of China(Nos.31472312,41306152,31402283)the Qingdao Innovation Talents Program(No.13-CX-16)+2 种基金the National Key Technology Research and Development Program of China(No.2014BAD08B09)the Earmarked Fund for Modern Agroindustry Technology Research System(No.CARS-48)the Project for International S&T Cooperation Program of China(No.2014DFA31030)
文摘The present study sampled the intestinal content of healthy and unhealthy Atlantic salmon (Salmo salar L.), the ambient water of unhealthy fish, and the biofilter material in the recirculating aquaculture system (RAS) to understand differences in the intestinal microbiota. The V4--V5 regions of the prokaryotic 16S rRNA genes in the samples were analyzed by MiSeq high-throughput sequencing. The fish were adults with no differences in body length or weight. Representative members of the intestinal microbiota were identified. The intestinal microbiota of the healthy fish included Proteobacteria (44.33%), Actinobacteria (17.89%), Baeteroidetes (15.25%), and Firmicutes (9.11%), among which the families Mierococcaceae and Oxalobacteraceae and genera Sphingomonas, Streptomyces, Pedobacter, Janthinobacterium, Burkholderia, and Balneimonas were most abundant. Proteobacteria (70.46%), Bacteroidetes (7.59%), and Firmicutes (7.55%) dominated the microbiota of unhealthy fish, and Chloroflexi (2.71%), and Aliivibrio and Vibrio as well as genera in the family Aeromonadaceae were most strongly represented. Overall, the intestinal hindgut microbiota differed between healthy and unhealthy fish. This study offers a useful tool for monitoring the health status of fish and for screening the utility of probiotics by studying the intestinal microbiota.
基金Supported by the Qingdao Postdoctoral Application Research Project(No.Y6KY01110N)the National Natural Science Foundation of China(Nos.31472312,41306152,31402283)+2 种基金the Qingdao Innovation Talents Program(No.13-CX-16)the National Key Technologies R&D Program of China(No.2014BAD08B09)the Earmarked Fund for Modem AgroIndustry Technology Research System(No.CARS-48)
文摘Although it has been hypothesized that a predictable feeding regime in animals allows physiological variables to be adjusted to maximize nutrient utilization and,hence,better growth performance,the assumption has rarely been tested.This study compares the effects of time-restricted versus free access self-feeding on the growth,feeding behavior and daily digestive enzyme rhythms of Atlantic salmon(Salmo salar).In an experiment that lasted 6 weeks,fish(109.9 g) were divided into two groups:group 1 had free access to a self-feeder(FA);group 2 received three meals per day(2 h per meal) at dawn,midday and dusk via a time-restricted self-feeder(TR).At the end of the experiment,the fish were sampled every 3 h over a24-h period.The results showed that the TR fish quickly synchronized their feeding behavior to the feeding window and their blood glucose showed a significant postprandial increase,while FA fish displayed no statistically significant rhythms(P>0.05).Pepsin activity of TR fish also showed a significant daily rhythm(P<0.05) with the acrophase at the second feed and a decrease over the next 12 h.Average daily trypsin,lipase and amylase levels of FA fish were significantly lower than those of TR fish(P<0.01);however,the growth performance of both groups was similar(P>0.05).In conclusion,the study failed to confirm a link between the entrainment of daily digestive enzyme profiles and growth performance,with the TR group showing comparatively poor blood glucose regulation.
基金supported by the National Key Technologies R&D Program(2011BAD13B04)the earmarked fund for Modern Agro-industry Technology Research System(CARS-48)the National Natural Science Foundation of China(No.31240012)
文摘The effects of different feeds and feeding regimes on growth performance, flesh quality and fecal viscosity of Atlantic salmon (Salmo salar L.) in recirculating aquaculture systems (R.AS) were investigated. Fish (initial body weight of 1677 g+ 157 g) were fed with four commercial feeds (Nosan salmon-NS, Aller gold-AG, Skretting salmon-SS and Hart ye-HY) in two feeding regimes (80% and 100% satiation) for 78 d. The results showed that salmon specific growth ratio (SGR) and weight gain ratio (WGR) were significantly affected by feed type and feeding regime (P〈0.05). Feed conversion ratio (FCR) varied between 0.93 and 3.40, which was significantly affected by feed type (P〈0.05), and slightly improved with increased satiation degree. The activities of digestive enzymes including protease, lipase and amylase were also significantly affected by feed type and feeding regime (P〈0.05), increasing with satiation degree. Flesh qualities for vitamin E, hydroxyproline (HYP), liquid loss and muscle pH among all groups showed significant differences (P〈0.05), ranging from 26.67 to 29.67, while no obvious difference was found in flesh color. Fecal viscosity for different treatments showed no significant difference, though improvement was found in 100% satiation group. From present experiment, it was concluded that both feed type and feeding regime can affect the important quality attributes of Atlantic salmon.
基金Supported by the Modern Agro-Industry Technology Research System(No.CARS-48)the National Natural Science Foundation of China(No.31240012)+1 种基金the Special Foundation for Postdoctoral Innovative Projects of Shandong Province(No.201101009)the National Key Technology R&D Program of China(No.2011BAD13B04)
文摘The combined effects of feeding rate(0.8%,1.0%,and 1.2%initial body weight/day),feeding frequency(two,three,and four times/day) and stocking density(10,15,and 20 kg/m3) in recirculating aquaculture systems(RAS) on growth performance,digestion and waste generation of Atlantic salmon(Salmo salar L.) were investigated in an 8-week orthogonal experiment(L9(3)3) with a constant daily water renewal at 7.50%of total volume.No mortality occurred during the experimental period.Feed conversion ratio(FCR) varied from 0.90 to 1.13 and specific growth rate(SGR) ranged from 0.48%to 0.69%/day.SGR,thermal growth coefficient(TGC) and FCR were not significantly(P>0.05) affected by the three factors,while net protein utilization(NPU) was significantly(P<0.05) affected.Apparent digestibility coefficients(ADC) of dry matter in the present study were in the range 66.12%-73.55%.ADC in protein,lipid and energy were statistically different among all treatments and in the range of 90.07%-93.67%,81.54%-89.15%,and67.55%-71.87%,respectively.The proportion of mean total ammonia nitrogen excreted ranged from 1.37%to 1.64%of feed nitrogen at steady state,and the concentration of nitrogenous and phosphorus compounds were differently correlated to the three factors.The results will provide valuable reference data for culture management decisions in the Atlantic salmon farming industry.
基金supported by Academy of Finland and the University of Helsinki
文摘The timing of river entry in the Atlantic salmon is known to depend on genetic, demographic and environmental factors, but little is known about the relative magnitude of among population and among year variation and covariation in this respect in natural state Atlantic salmon rives. To investigate this, variability in the timing of river entry in three historical Finnish Atlantic salmon populations were analyzed using salmon trap data collected during 1870- 1902. The analyses reveled that 1 ) the timing of river entry differed substantially and consistently among the rivers, and that 2) variation among the rivers was much larger than variation among years. Annual variations were not explained by regional environmental conditions, whereas in one river the timing of the local flood peak was a significant predictor of the timing of river entry. Differences in the timing of salmon entry to geographically closely situated rivers suggests that a regionally fixed opening date for coastal fisheries might not be the best management strategy as it may lead to uneven exploitation of salmon populations from different rivers [ Current Zoology 55 (5) : 342 - 349, 2009] .
文摘The aim of this study was to evaluate the effects of pumping height and repeated pumping on the generalized stress response and gross injuries in harvest sized Atlantic salmon. Fish pumped from a net pen at either high (5.2 m) or low (3.6 m) pumping heights showed an elevated, but not severe physiological stress response (pH, pCO<sub>2</sub>, lactate, potassium, haematocrit, and sodium) compared to fish netted (not pumped), while effects of different pumping heights were overall not demonstrated. Repeated pumping (either 3 or 6 times) also caused an increase in stress response (pH, pCO<sub>2</sub>, pO<sub>2</sub>, lactate, potassium and sodium) compared to control fish, and a positive dose-response relationship was found for lactate. No fish died as a result of pumping, nor were injuries observed that could exclusively be attributed to pumping. In conclusion, although elevated from the control groups, the stress response following increasing pumping height and repeated pumping as conducted in these experiments were not indicative of causing severe stress or injuries.
基金Grant Fondecyt 1200523Fondecyt 3160835 and Fondecyt 1171129 from Fondo Nacional de Desarrllo Científico y Tecnologico,CONICYT/ANID,Chile.We would like to thanks to Mauricio Valdes for technical support.
文摘Atlantic salmon(Salmo salar)fed a carbohydrate-rich diet exhibit suboptimal growth performance,along with other metabolic disturbances.It is well known that gut microbes play a pivotal role in influencing metabolism of the host,and these microbes can be modified by the diet.The main goal of the present study was to determine the effect of feeding graded levels of digestible carbohydrates to Atlantic salmon on the distal intestine digesta microbiota at 3 sampling times(i.e.,weeks 4,8 and 12),during a 12-week trial.A low carbohydrate-to-high protein diet(LC/HP,0%wheat starch),a medium carbohydrate-tomedium protein diet(MC/MP,15%wheat starch)or a high carbohydrate-to-low protein diet(HC/LP,30%wheat starch)was fed to triplicate fish tanks(27 to 28 fish per tank).We performed an in-depth characterization of the distal intestine digesta microbiota.Further,growth parameters,liver histology and the expression of genes involved in hepatic neolipogenesis in fish were measured.Fish fed a HC/LP diet showed greater hepatosomatic and viscerosomatic indexes(P=0.026 and P=0.018,respectively),lower final weight(P=0.005),weight gain(P=0.003),feed efficiency(P=0.033)and growth rate(P=0.003)compared with fish fed the LC/HP diet.Further,feeding salmon a high digestible carbohydrate diet caused greater lipid vacuolization,steatosis index(P=0.007)and expression of fatty acid synthase(fas)and delta-6 fatty acyl desaturase(d6fad)(P=0.001 and P=0.001,respectively)in the liver compared with fish fed the LC/HP diet.Although,the major impact of feeding a carbohydrate-rich diet to Atlantic salmon in beta diversity of distal intestine digesta microbiota was observed at week 4(HC/LP vs MC/MP and HC/LP vs LC/HP;P=0.007 and P=0.008,respectively)and week 8(HC/LP vs MC/MP;P=0.04),no differences between experimental groups were detected after 12 weeks of feeding.Finally,at the end of the trial,there was a negative correlation between lactic acid bacteria(LAB)members,including Leuconostoc and Lactobacillus,with hepatic steatosis level,the hepatosomatic and viscerosomatic indexes as well as the expression of fas and d6fad.Weissella showed negative correlation with hepatic steatosis level and the hepatosomatic index.Finally,further research to explore the potential use of LAB as probiotics to improve liver health in carnivorous fish fed fatty liver-induced diet is warranted.
文摘Electronic tags are widespread tools for studying aquatic animal behavior;however,tags risk behavioral manipulation and negative welfare outcomes.During an experiment to test behavioral differences of Atlantic salmon Sal mo salar in different aquaculture cage types,including ones expected to elicit deeper swimming behavior,we found negative tagging effects depending on whether cages were depth-modified.In the experiment,data storage tags implanted in Atlantic salmon tracked their depth behavior and survival in unmodified sea-cages and depth-modified seacages that forced fish below or into a narrow seawater-or freshwater-filled snorkel tube from a 4 m net roof to the surface.All tagged individuals survived in unmodified cages;however,survival was reduced to 62%in depth-modified cages.Survivors in depth-modified cages spent considerably less time above 4 m than those in unmodified cages,and dying individuals in depth-modified cages tended to position in progressively shallower water.The maximum depth that fish in our study could attain neutral buoyancy was estimated at 22 m in seawater.We calculated that the added tag weight in water reduced this to 8 m,and subtracting the tag volume from the peritoneal cavity where the swim bladder reinflates reduced this further to 4 m.We conclude that the internal tag weight and volume affected buoyancy regulation as well as the survival and behavior of tagged fish.Future tagging studies on aquatic animals should carefully consider the buoyancy-related consequences of internal tags with excess weight in water,and the inclusion of data from dying tagged animals when estimating normal depth behaviors.
文摘Road salts are frequently used for deicing of roads in the Nordic countries. During snow-melt, the road run-off containing high concentrations of road salt and various metals such as Cu remobilized from sand, silt and dust may negatively influence organisms in downstream receiving water bodies. The present work focuses on the impact of road salt(NaCl) and Cu, separately and in mixtures on Atlantic salmon alevins from hatching till swim-up. The results showed that high road salt concentrations could induce a series of negative effects in alevins such as reduced growth, deformities, delayed swim-up and mortality. For alevins exposed to all tested road salt concentrations(100–1000 mg/L),mortality was significantly higher compared to control. In exposure to Cu solutions(5–20 μg Cu/L), no effects on growth, morphology, swim-up or mortality of alevins compared to control were observed. In mixture solutions(road salt and Cu), ultrafiltration of the exposure water demonstrated that only 20%–40% of Cu was present as positively charged low molecular mass(LMM) Cu species assumed to be bioavailable. When exposed to road salt and Cu mixtures, negative effects in alevins such as reduced growth, deformities,delayed swim-up and mortality were observed. The overall results indicated that the road salt application could seriously affect sensitive life stages of Atlantic salmon, and application of road salt should be avoided during the late winter–early spring period.