Effects of lighting mode on the growth performance,cortisol level and oxidative stress of juvenile Chinese three-keeled pond turtle(Chinemys Reevesii)

To improve the light environment and welfare of the turtle cultured indoors,the effects of lighting mode on growth performance,cortisol level,and oxidative stress of juvenile Chinese three-keeled pond turtle,Chinemys reevesii,were investigated in this study.The experimental turtles with an initial weight of 5.61±0.09 g were reared in tanks under four different lighting modes:three groups with light(lighting the basking area and water area,LBW;lighting the water area only,LW;lighting the basking area only,LB)and control group(no light,NL).The experiment was conducted for more than six months,with each group having three replicates.After 203 d of the experiment,the turtle in the LW group exhibited higher weight gain rate(WGR)and a specific growth rate(SGR,%/d)compared to other treatments.Also,results showed that the final body weight of the turtle exposed to LW was higher than that exposed to other treatments.On the physiological level,serum cortisol level in turtles exposed to LW was significantly lower than that in other treatments.Regarding oxidative stress,the level of catalase(CAT)in turtles exposed to LW and LB was significantly lower than that exposed to LBW and NL.The malonaldehyde(MDA)activity in turtles exposed to LW was significantly lower than other treatments.Based on the growth performance and health status,it is suggested that lighting the water area only is the optimal lighting mode for the juvenile threekeeled pond turtle cultured indoors.

AMMONIA DISPERSION FROM MULTI-FLOOR VERSUS STANDARD SINGLE-FLOOR PIG PRODUCTION FACILITIES BASED ON COMPUTATIONAL FLUID DYNAMICS SIMULATIONS

Multi-floor buildings for raising pigs have recently attracted widespread attention as an emerging form of intensive livestock production especially in eastern China,due to the fact that they can feed a much larger number of animals per unit area of land and thus alleviate the shortage of land available for standard single-floor pig production facilities.However,this more intensive kind of pig building will pose new challenges to the local environment in terms of pollutant dispersion.To compare the dispersion air pollutants(ammonia as a representative)emitted from multi-versus single-floor pig buildings,ammonia dispersion distance and concentration gradients were investigated through three-dimensional simulations based on computational fluid dynamics.The validation of an isolated cubic model was made to ensure the simulation method was effective.The effects of wind direction,wind speed and emission source concentration at 1.5 m(approximate human inhalation height)during summer were investigated.The results showed that the ammonia dispersion distance of the multi-floor pig building was far greater than that of the single-floor building on a plane of Z=1.5 m.When the wind direction was 67.5°,the wind speed was 2 m·s^(−1) and the emission source concentration was 20 ppmv,the dispersion distance of the multi-floor pig building could reach 1380 m.Meanwhile,the ammonia could accumulate in the yard to 7.68 ppmv.Therefore,future site selection,wind speed and source concentration need to be given serious consideration.Based on the simulation used in this study with source concentration is 20 ppmv,the multi-floor pig buildings should be located 1.4 km away from residential areas to avoid affecting residents.The results of this study should guidance for any future development of multi-floor pig buildings.

Recent advances in application of moving bed bioreactors for wastewater treatment from recirculating aquaculture systems: A review

In recent years,government investments in implementing restrictive public policies on the treatment and discharge of effluents from the aquaculture industry have increased.Hence,efficient and cleaner methods for aquaculture production are needed.Recirculating aquaculture systems(RAS)offers water conservation by recycling the treated aquaculture water for reuse.RAS wastewater treatment using a moving bed bioreactors(MBBRs)process has been considered well suited for maintaining good water quality,thereby making fish farming more sustainable.Currently,improvements were achieved in tackling the influence of salinity,organic matter,disinfectant,and bioreactor start-up process on the MBBR performance efficiency.This review highlights an updated overview of recent development made using MBBR to treat the residual water from RAS.Precisely,nitrification and simultaneous nitrification-denitrification(SND),and other hybrid processes for nitrogen removal were elucidated.Finally,future challenges and prospects of MBBRs in RAS facilities that need to be considered were also proposed.

Preservative effects of the combined treatment of slightly acidic electrolyzed water and ice on pomfret

This study assessed the combined effect of slightly acidic electrolyzed water(SAEW)and slightly acidic electrolyzed water ice(SAEW-ice)on the quality of pomfrets over a period of 18 d of cold storage at 4°C.A presoak for 5 min in SAEW solution(22 mg/L)was used before the pomfrets were placed on SAEW-ice(pH:6.45;ORP:803 mV;ACC:18 mg/L);The changes in physicochemical properties(i.e.,pH,thiobarbituric acid,total volatile basic nitrogen and texture profile),microbial loads and sensory characteristics were all analyzed.Compared with the tap water(TW)group,the total bacterial counts of the SAEW group significantly decreased by 1.27 log10 CFU/g after immersion(p<0.05).The shelf life of the pomfrets was prolonged by 9 d by the combined treatment of SAEW and SAEW-ice during storage at 4℃.On the 18th day,the gumminess and chewiness values of the pomfrets in the SAEW+SAEW-ice group were 195 g and 3.97 mJ,respectively,which were significantly higher than those of the other groups(p<0.05).The results suggested that SAEW+SAEW-ice treatments have great potential as a novel method to maintain the quality and extend the shelf life of pomfrets during refrigerated storage.

Disinfection effect of adding slightly acidic electrolyzed water to artificial seawater under the condition of static hybrid

Mixed solution of slightly acidic electrolyzed water(SAEW)and artificial seawater was used to investigate the disinfection potential of SAEW in artificial seawater.Inoculated Vibrio parahaemolyticus(suspended in 3%sodium chloride alkaline peptone water and 0.85%sodium chloride water,respectively)was subjected to different mixed-SAEW and SAEW immersion treatments(5-20 mg/L available chlorine concentration(ACC)).In the presence of organic matter,4.07 logCFU/mL significant reduction(p<0.05)was achieved after treating with 20 mg/L mixed-SAEW for 15 min.There was 5.13 logCFU/mL reduction after treating with 15 mg/L SAEW for 15 min.For V.parahaemolyticus suspended in 0.85%sodium chloride solution,it was undetected after 30 s SAEW treatment(5 mg/L ACC)or 120 s mixed-SAEW treatment(10 mg/L ACC).At a ratio of SAEW and artificial seawater at 1:15(V/V),SAEW could inactivate V.parahaemolyticus to undetectable level in artificial seawater in one minute,which was comparable with UV treatment of 10 W.The results indicated high sanitization potential of SAEW against V.parahaemolyticus in aquaculture seawater.

Light spectrum preference of Nile Tilapia (Oreochromis niloticus) under different hunger levels

In order to improve the light welfare of Nile tilapia in aquaculture,the influence of hunger level on light spectrum preference of Nile tilapia was explored in this study.The whole experiment was based on the emptying of the gastrointestinal contents,and carried out under the controlled laboratory conditions.The light spectrum preference was assessed by counting the head location of fish in each experimental tank,which containing seven compartments(i.e.,red,blue,white,yellow,black,green and public area).t-Distributed Stochastic Neighbor Embedding(t-SNE)was adopted to visualize the hunger level-based dynamic preference on light spectrum in two-dimensional space.According to the clustering results,significant differences in light spectrum preferences of Nile tilapia,under the different hunger levels,were indicated.In addition,the average visit frequency in green compartment was significantly lower than that in other color compartments throughout the whole experiment,and the total visit frequency in red compartment was relatively higher during the whole experiment.

Effects of flow velocity on water quality and ammonia excretion in recirculating aquaculture system culturing juvenile largemouth bass(Micropterus salmoides)

Flow velocity plays an important role in recirculating aquaculture systems(RAS)and the growing practice of culturing juvenile largemouth bass(Micropterus salmoides).In this study,the effects of flow velocity on the water quality as well as the ammonia excretion were discussed from the perspective of actual production,and a polynomial model of ammonia nitrogen excretion was established,using the juvenile largemouth bass.Results showed that the range of ammonia nitrogen and nitrite nitrogen decreased with flow velocity increasing,while the number and volume share of large particles increased.According to the polynomial model,compared with the medium flow velocity(11 cm/s,2.45 body length(bl)/s),the ammonia excretion of juvenile largemouth bass at high(18 cm/s,4.00 bl/s),and low(4 cm/s,0.90 bl/s)flow velocity changed faster with time,and the excretion rate peaked at the 6th hour after feeding,earlier than that under medium flow velocity.Therefore,it is suggested to increase the flow velocity at the 5th hour after feeding and then decreased it at the 10th hour,to ensure better water quality in RAS culturing juvenile largemouth bass.

Effects of intelligent feedingmethod on the growth,immunity and stress of juvenile Micropterus salmoides

The feeding method is of great significance for aquaculture production and cost.In recent years,research on intelligent feeding,a method based on fish appetite,has been trending.Fewstudies,however,have focused on fish welfare issues that can result from intelligent feeding.In this study,an adaptive feeder based on a practical intelligent feeding method was designed to evaluate whether this intelligent feeding method would impair fish welfare compared to traditional automatic feeding.The results indicated that the amount of residual feed and size inhomogeneity in the traditional group was significantly higher than that in the intelligent group.The results of the growth indicator showed that theweight gain rate(WGR)in the intelligent feeding groupwas significantly higher(30.17%)than in the traditional feeding group.Although no significant differences were observed in the survival rate(SR),the condition factor(CF)and the hepatosomatic index(HSI),the specific growth rate(SGR)in the intelligent feeding group was significantly increased by 8.33%while the feed conversion rate(FCR)was reduced by a remarkable 17.07%compared to the traditional feeding group.Moreover,intelligent feeding significantly improved the pepsin activity of the bass.In terms of immunity and antioxidant capacity,however,the fish in the intelligent feeding group had a significantly lower lysozyme(LZM)level than those fed with the traditional method.For superoxide dismutase(SOD),the intelligent group also displayed a lower activity value,although it was not significant.The intelligent feeding group had 0.14 nmol/mg protein higher malondialdehyde(MDA)activity than the traditional group.Regarding stress,although no statistical significance was observed,the cortisol level in the intelligent group was 1.9 ng/ml higher than in the traditional group.Together,these data suggested that the intelligent feeding method can significantly improve fish growth but may also result in stress and suppress innate immunity.