天津市水产研究所

The experiment aimed to investigate the effects of adding chromium methionine(CrMet)to high carbohydrate feed on the growth performance,antioxidant capacity,serum biochemical indicators,and hepatopancreas health in common carp.A total of 180 healthy carp with an initial weight of(86.61±6.68)g were randomly divided into three groups,with three replicates per group and 20 carp per replicate.Three types of feed were prepared:Control group(CK,carbohydrate level 25％),high carbohydrate group(HCD,carbohydrate level 45％),and high carbohydrate feed supplemented with CrMet(HCD+Cr,1 mg/kg Cr3+).The preliminary period was one week,and the formal experimental period was 60 days.The results showed that long-term feeding with high carbohydrate feed did not negatively affect the growth performance of common carp,but it led to a significant increase in the levels of glucose(GLU),low-density lipoprotein(LDL),glutamic-pyruvic transaminase(ALT),alkaline phosphatase(AKP)activities,and malondialdehyde(MDA)content in the serum and hepatopancreas of common carp(P＜0.05),and a significant decrease in total antioxidant capacity(T-AOC),superoxide dismutase(SOD),catalase(CAT),and glutathione peroxidase(GSH-Px)activities(P＜0.05),causing oxidative stress.Prolonged oxidative stress conditions significantly increased the levels of pro-inflammatory factors interferon-γ(IFN-γ)and interleukin-1β(IL-1β)in common carp(P＜0.05).The addition of CrMet had no significant effect on the growth performance of common carp(P＞0.05),but compared with the HCD group,the levels of GLU,LDL,GPT,and aspartate aminotransferase(AST)activity,AKP activity,MDA content,and IL-1β,IFN-γ,and tumor necrosis factor-α(TNF-α)levels in the serum of common carp were significantly reduced(P＜0.05),while the levels of high-density lipoprotein(HDL),GSH-Px,SOD,and CAT activities were significantly increased(P＜0.05).Histological results showed that the addition of CrMet could significantly improve the degree of degeneration of common carp hepatocytes.The study indicates that after consuming high carbohydrate feed,common carp were in a state of oxidative stress,inducing inflammatory responses.The addition of 1 mg/kg CrMet can enhance the antioxidant capacity of common carp hepatopancreas,alleviate inflammation induced by high carbohydrate feed,and mitigate liver damage.

The study aimed to investigate the effects of Astragalus polysaccharides(APS)on the growth performance,antioxidant capacity,and immune function in Cynoglossus semilaevis.The experiment consisted of two parts.The first part involved an in vitro immune induction test,where peripheral blood leukocytes of Cynoglossus semilaevis were incubated with cell culture medium containing 10,100,or 1 000 mg/L APS to measure immune cell activity and in vitro induction of immune-related gene expression.The second part was an in vivo feeding trial,in which 240 Cynoglossus semilaevis were randomly divided into four groups(three replicates per group,20 fish per replicate).The control group(Group C)was fed a basal diet,while the experimental groups(Groups A1,A2,and A3)were fed the basal diet supplemented with 0.1%,0.2%,and 0.4%APS,respectively,for 28 days.Results showed that compared to the control,1 000 mg/L APS significantly enhanced cellular respiratory burst activity(P<0.05)and upregulated interleukin-8(IL-8)and tumor necrosis factor-α(TNF-α)expression in leukocytes at 12,24,and 48 h(P<0.05).After 28 days of feeding,the final body weight,weight gain rate,and specific growth rate in Groups A2 and A3 were significantly higher than those in Group C(P<0.05).In Group A3,serum superoxide dismutase(SOD)and catalase(CAT)activities on days 7 and 21,as well as serum interferon(IFN)content,were significantly higher than in other groups(P<0.05).Serum lysozyme(LZM)activity on days 21 and 28 in Group A3 was also significantly elevated(P<0.05).In Group A2,SOD and CAT activities on day 7 were significantly lower than in Group C(P<0.05),while serum complement 3(C3)content was significantly higher(P<0.05).All experimental groups exhibited significantly higher splenic IL-1β mRNA expression than Group C(P<0.05).On day 21,IL-1β and IL-8 mRNA expression in the head kidney and blood of Group A3 were significantly higher than in other groups(P<0.05).On days 7,14,and 21,splenic IL-8 mRNA expression in Groups A2 and A3 was significantly higher than in Group C(P<0.05).On day 28,blood Toll-like receptor 2(TLR2)mRNA expression in all experimental groups was significantly elevated compared to Group C(P<0.05).On days 7 and 21,head kidney TLR2 mRNA expression in Groups A2 and A3 was significantly higher than in Group C(P<0.05),while splenic TLR2 mRNA expression in Group A3 was significantly higher than in other groups on days 7 and 14(P<0.05).This studys show that APS exhibits immunostimulatory effects on Cynoglossus semilaevis peripheral blood leukocytes in vitro,and dietary supplementation with APS improves growth performance,antioxidant capacity,and immune function in Cynoglossus semilaevis,with 0.4%APS showing the optimal efficacy.

Rhynchochypris lagowskii is a small freshwater economic fish species selected by the Ministry of Agricul-ture and Rural Affairs as one of the top 10 characteristic aquatic germplasm resources in 2022.To investigate the genetic diversity of the R.lagowskii populations in northern China and provide references for its conservation and genetic breeding,Genotyping by sequencing(GBS)was used to develop single nucleotide polymorphism(SNP)mar-kers and analyze genetic characteristics of 109 individuals from four R.lagowskii populations in Ninghe,Jizhou,Juhe(Tianjin),and Taizihe(Liaoning).Through sequencing,a total of 3723530 SNP markers were obtained,and 133536 high-quality SNP loci were screened for genetic analysis after filtering.The expected heterozygosity(He)of the four populations was 0.0397-0.0884,the observed heterozygosity(Ho)was 0.0394-0.0818,the nucleotide diversity(Pi)was 0.0406-0.098,the polymorphic information content(PIC)value was 0.0327-0.0717,the genetic differentiation coefficient(FST)was 0.0039-0.8148,and the inbreeding coefficient(Fis)within population was 0.0567-0.5480.Genetic structure analysis showed that four populations clustered into three distinct groups,with individuals from the Ninghe and Jizhou populations in Tianjin clustered into one branch,and individuals from the Taizihe and Juhe popula-tions in Liaoning and Tianjin clustered into one branch,respectively.Population specific SNP markers were identified for all four populations,serving as candidate molecular markers for species identification,population genetics,trait association analysis,and evolutionary studies.Population history dynamics research indicates that the four populations of R.lagowskii all underwent a process characterized by a sharp decline in effective population size(Ne)during the Quaternary glacial period.

The experiment aimed to explore the effects of dietary arginine addition on growth performance,intestinal digestive enzyme activity,antioxidant and immune indicators of Apostichopus japonicus.A total of 400 healthy Apostichopus japonicus with a weight of(6.6±0.2)g were randomly divided into five groups,with four replicates in each group and 20 Apostichopus japonicus in each replicate.The control group(group A)was fed a basal diet,while experimental groups B,C,D,and E were fed diets containing 0.33％,0.67％,1.00％,and 1.33％arginine,respectively.The culture period was 60 days.The results showed that compared with the group A,the weight gain rate,specific growth rate,and protein efficiency of Apostichopus japonicus in groups B,C,and D were significantly increased(P＜0.05),while the feed conversion ratio and viscera-to-body wall ratio were significantly decreased(P＜0.05).The activities of intestinal amylase,trypsin and lipase in group D Apostichopus japonicus,as well as the catalase,superoxide dismutase and total antioxidant capacity in the body cavity fluid were significantly increased(P＜0.05),and the content of malondialdehyde was significantly low(P＜0.05).With increasing dietary arginine levels,alkaline phosphatase activity in coelomic fluid gradually increased(P＜0.05).Group D exhibited the highest total nitric oxide synthase and inducible nitric oxide synthase activities,and the highest nitric oxide content(P＜0.05).The study indicates that 1.00％dietary arginine supplementation optimally promotes Apostichopus japonicus growth and development,while excessive addition may induce negative feedback inhibition.

The experiment aimed to study the muscle nutritional components of paddy crabs and pond crabs farmed in two habitats.Thirty 'Photosynthetic No.1'mitten crabs were randomly selected from paddy crabs and pond crabs,and analyzed using universal nutritional testing methods.The results showed that compared to pond crabs,the moisture and fat content in paddy crabs were significantly reduced(P＜0.05).Both paddy crabs and pond crabs contained 18 kinds of amino acids in their muscles.The total amino acid(TAA),essential amino acid(EAA)and non-essential amino acid(NEAA)contents in paddy crabs were significantly higher than in pond crabs(P＜0.05).The EAA composition ratio in both habitats met the FAO/WHO standard.Based on amino acid scoring(AAS)and chemical scoring(CS),tryptophan was the first limiting amino acid,and valine the second.Twenty and fourteen fatty acids were detected in the muscles of paddy crabs and pond crabs,with contents of 0.86％and 0.79％,respectively,and the total amount of fatty acids in paddy crabs was significantly higher than that in pond crabs(P＜0.05).The fatty acids such as lauric acid,myristic acid,pentadecanoic acid,margaric acid,trans-oleic acid and cis-11,14,17-eicosatrienoic acid were only detected in paddy crabs.Compared to pond crabs,paddy crabs exhibit significantly higher levels of phosphorus,calcium,iron,manganese,zinc and selenium(P＜0.05).The study indicates that river crabs raised in rice fields are healthier,allowing for a double harvest from one field,and their muscle nutritional value is superior to that of pond crabs.