Shiwei Xie

Effect of deoxynivalenol on growth performance, histological morphology, anti-oxidative ability and immune response of juvenile Pacific white shrimp, Litopenaeus vannamei

Abstract A 5‐weeks experiment was conducted to evaluate the effect of deoxynivalenol on growth performance, histological morphology, anti‐oxidative ability and immune capacity of Litopenaeus vannamei. White shrimp (mean initial weight 1.02 g) were fed seven isonitrogenous diets, Diet 1 as the control, Diet 2–4 was supplemented with grade levels (250, 500 and 1000 &mgr;g kg−1) of deoxynivalenol (DON), Diet 5–7 were formulated to contain graded levels of contaminated wheat flour. Each diet was assigned to four tanks (30 shrimp). The weight gain was decreased with the increasing dietary DON levels, survival was lower in shrimp fed high levels of DON‐contaminated wheat flour (P < 0.05). Feed intake and feed conversion ratio did not show any difference among all the groups. After 4 h hypoxia stress, survival of shrimp was decreased in shrimp fed high levels of DON‐contaminated wheat flour (P < 0.05). Total antioxidant capacity in hepatopancreas was higher in shrimp fed the control diet, glutathione S‐transferase (GST) activity were higher in shrimp fed the Diet 3 and Diet 6, superoxide dismutase (SOD) activity was higher in shrimp fed the highest dietary DON (Diet 4), while the gene expression of SOD and GPx were lower in shrimp fed the Diet 3–7. The expression of HSP70, Toll 1 and Dorsal were higher in shrimp fed the Diet 2, the expression of AKT were higher in shrimp fed the Diet 1 and Diet 2. The expression of proPO, LGBP and PPAF were higher in shrimp fed the Diet 4 and Diet 7. The H&E stain indicated intestinal mucosal folds were impaired in shrimp fed the Diet 3–7, and B cells number and diameters of the hepatopancreas tubules were affected by DON levels, and transmission electron microscope (TEM) analysis indicated the apopotosis occurs in intestinal epithelial cell of shrimp fed the Diet 2–7. Based on the present results, the safety level of DON for white shrimp should below 0.5 ppm, which was much less than the European Communities recommendation values for aquatic animals (5 ppm). High level of DON would damage the cell structural and affect the NF‐&kgr;B pathway and proPO system of shrimp. HighlightsWeight gain and survival of shrimp were impaired by the dietary DON.Intestinal mucosal and the microstructural of intestinal epithelial cell were harmed by dietary DON.NF‐kB pathway and proPO system were affected by dietary DON.

Dietary values of Forsythia suspensa extract in Penaeus monodon under normal rearing and Vibrio parahaemolyticus 3HP (VP 3HP ) challenge conditions: Effect on growth, intestinal barrier function, immune response and immune related gene expression

ABSTRACT Two trials were conducted to determine the effects of dietary Forsythia suspensa extract (FSE) on shrimp, Penaeus monodon, first on growth performance, second on the immune response and immune related gene expression of shrimp. In trial 1, shrimp (mean initial wet weight about 3.02 g) were fed with five diets containing 0% (basal diet), 0.01%, 0.02%, 0.04% and 0.06% FSE in triplicate for 60 days. Growth performance (final body wet weight, FBW; weight gain, WG; biomass gain, BG) of shrimp fed FSE diets were higher (P < 0.05) than that of shrimp fed the basal diet. The survival among all the diets treatments were above 90% and no significant difference was revealed among them (P > 0.05). The antioxidant capacity (total antioxidant status, TAS; glutathione peroxidase, GSH‐Px) appears in the trend of firstly increasing then decreasing with the increasing of dietary FSE levels. The highest value of TAS and GSH‐Px were found in shrimp fed 0.02% FSE diet and were significantly higher than that of shrimp fed the basal and 0.06% FSE diets (P < 0.05). Hepatopancreas malondialdehyde (MDA) of shrimp fed FSE diets were lower (P < 0.05) than that of shrimp fed the basal diet. Total haemocyte count of shrimp fed the basal diet was lower (P < 0.05) than that of shrimp fed FSE diets. Haemolymph clotting time of shrimp had the opposite trend with the total haemocyte count of shrimp. No significant differences were found in haemolymph biomarkers of intestinal permeability (endotoxin and diamine oxidase) and in molecular gene expression profiles of heat shock protein 70 (Hsp 70) mRNA and hypoxia inducible factor‐1&agr; (HIF‐1&agr;) mRNA in haemolymph of shrimp among all diet treatments (P > 0.05). In trial 2, a pathogenic strain of Vibrio parahaemolyticus 3HP (VP3HP) injection challenge test was conducted for 6‐day after the rearing trial and shrimp survival were also compared among treatments. Survival of shrimp fed diets supplemented with 0.01%–0.02% FSE were higher than that of shrimp fed the basal and 0.06% FSE diets (P < 0.05). Dietary FSE supplementation produced stronger hepatopancreas antioxidant capacity (TAS, GSH‐Px) (P < 0.05) and higher glutathione (GSH) level (P < 0.05), lower superoxide dismutase activity (SOD) (P < 0.05), higher total haemocyte count (P < 0.05), lower haemolymph clotting time (P < 0.05), lower MDA and carbonyl protein concentration (P < 0.05), lower haemolymph biomarkers of intestinal permeability (endotoxin and diamine oxidase) (P < 0.05), generated lower molecular gene expression profiles of HSP 70 mRNA and higher HIF‐1&agr; mRNA (P < 0.05) than the basal diet. The immune response were characterized by lower TAS and higher antioxidant enzyme activities (SOD, GSH‐Px) and higher oxidative stress level (MDA and carbonyl protein) and higher haemolymph biomarkers of intestinal permeability (endotoxin and diamine oxidase) compared to levels found in trail 1. However, the total haemocyte counts and haemolymph clotting times were not changed in 0.01%–0.02% FSE diets treatments between trial 1 and trial 2 (P > 0.05). The molecular gene expression profile of Hsp 70 mRNA was increased while HIF‐1&agr; mRNA was decreased when compared to trial 1. In conclusion, results suggested that dietary intake containing FSE could enhance the growth performance and antioxidant capacity of P. monodon and furthermore reduce oxidative stress and immune depression challenged by a pathogenic strain of Vibrio parahaemolyticus stress. Considering the effect of FSE on both growth performance and immune response of P. monodon, the level of FSE supplemented in the diet should be between 0.01% and 0.02%. HighlightsDietary Forsythia suspensa extract could enhance the growth performance of P. monodon..Dietary Forsythia suspensa extract could improve P. monodon resistance to Vibrio parahaemolyticus 3HP (VP3HP) challenge.Economic dietary Forsythia suspensa extract level should be between 0.01% and 0.02%.

Dietary values of macroalgae Porphyra haitanensis in Litopenaeus vannamei under normal rearing and WSSV challenge conditions: Effect on growth, immune response and intestinal microbiota

&NA; Two trials were conducted to determine the effects of dietary macroalgae Porphyra haitanensis on growth, immunity and intestinal microbiota of Litopenaeus vannamei. In trial 1, shrimp (mean initial wet weight about 0.64 g) were fed with seven diets (P0, P1, P2, P3, P4, P5 and P6) containing 0% (basal diet), 1%, 2%, 3%, 4%, 5% and 6% P. haitanensis in triplicate for 60 days. Growth performance (weight gain, WG; specific growth rate, SGR) of shrimp fed the P4 diet were significantly higher than that of shrimp fed P0, P5 and P6 diets (P < 0.05) but without significant differences with shrimp fed P1‐P3 diets (P > 0.05). Hepatopancreas phenoloxidase (PO) activity of shrimp fed the P. haitanensis containing diets was significantly higher than that of shrimp fed the basal diet (P0) (P < 0.05). Total haemocyte count (THC) of shrimp fed basal diet (P0) was significantly lower than that of shrimp fed diets containing P. haitanensis. Our results declared that dietary P. haitanensis supplementation increases the abundance of beneficial bacterials such as Nitrosopumilus, Marinobacter or Bifidobacterium and reduces the abundance of harmful bacterias such as Vibrio, and especially pronounced in P4 diet treatment. In trial 2, a WSSV injection challenge test was conducted for 7‐day after the rearing trial and shrimp survival was also compared among treatments. A sudden shrimp death was found from the 4th day, and values of survival of shrimp fed the P3‐P4 diets were higher than that of shrimp fed other diets during 4–7 days challenge test. The immune response in trial 2 were characterized by higher superoxide dismutase activity (SOD) and PO activities, lower THC and higher HCT compared to levels found in trial 1. In conclusion, suitable dietary P. haitanensis could enhance the growth performance, antioxidant capacity and alter total bacterial numbers or microbial diversity of L. vannamei and furthermore reduce oxidative stress and immune depression challenged by WSSV injection stress, and the level of P. haitanensis supplemented in the diet should be between 2.51% and 3.14%. HighlightsSuitable P. haitanensis improves growth, immune and WSSV challenge of L. vannamei.P. haitanensis alters intestinal microbiota composition in bidirectional effects.Economic dietary P. haitanensis level should be between 2.51% and 3.14%.

Dietary supplementation of Haematococcus pluvialis improved the immune capacity and low salinity tolerance ability of post-larval white shrimp, Litopenaeus vannamei

&NA; A 25‐days experiment was conducted to evaluate the effect of dietary Haematococcus pluvialis on growth, survival, immune response and stress tolerance ability of post‐larval Litopenaeus vannamei. Post‐larval white shrimp (mean initial weight 2.1 mg) were fed five isoenergic and isonitrogenous diets containing grade levels of Haematococcus pluvialis (0, 1.7, 3.3, 6.7 and 13.3 g kg−1 diet, respectively). Results indicated that 3.3 g Haematococcus pluvialis kg−1 diet increased the survival rate of post‐larval white shrimp. Specific growth rate (SGR) and weight gain (WG) showed no difference among each groups. After the acute salinity stress (salinity decreased rapidly from 28‰ to 5‰), survival of shrimp fed 6.7 g Haematococcus pluvialis kg−1 diet significant higher than the control (P < 0.05), and the total antioxidant capacity (T‐AOC) was increased with the increasing dietary Haematococcus pluvialis levels. The malonaldehyde (MDA) contents in whole body decreased with the increasing dietary Haematococcus pluvialis levels before and after the salinity stress. Before the salinity stress, relative mRNA levels of Caspase 3, Rho and Janus kinase (JAK) decreased in shrimp fed diets contain Haematococcus pluvialis. After the salinity stress, relative mRNA levels of anti‐oxidative related genes and immune related genes decreased with the dietary Haematococcus pluvialis level increased to 3.3 g kg−1. Based on the effect of Haematococcus pluvialis on survival, salinity stress tolerance ability and the immune response of post‐larval L. vannamei, the optimal level of Haematococcus pluvialis was 3.3–6.7 g kg−1 diet (100–200 mg astaxanthin kg−1 diet). HighlightsSupplementation of 3.3 g Haematococcus pluvialis kg−1 diet increased the survival rate of post‐larval white shrimp.Supplementation of 6.7 g Haematococcus pluvialis kg−1 diet improved the low salinity stress resistance of white shrimp.Dietary Haematococcus pluvialis improved the anti‐oxidative ability and immune capacity of post‐larval L. vannamei.