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The present study was conducted to investigate the effects of Haematococcus pluvialis on growth performance, antioxidant capacity, immune responses and resistance to Vibrio harveyi of spotted sea bass Lateolabrax maculatus. Fish were fed with six diets containing grade levels of containing H. pluvialis (0, 2, 4, 6, 8 and 1 g/kg, respectively) in triplicate for 8 weeks, followed by a V. harveyi infection test for 7 days. The astaxanthin concentrations of diets were 1.14 (control), 30.23 (T1), 58.42 (T2), 91.51 (T3), 118.61 (T4) and 150.31 mg/kg (T5). Results showed that dietary H. pluvialis increased final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) and decreased the whole body lipid of fish (p <.05). Dietary H. pluvialis improved the hepatic total antioxidant capacity (T‐AOC) and decreased the levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities, and malondialdehyde (MDA) contents of fish (p <.05). In fish fed the H. pluvialis supplemented diets, the levels of triglyceride, cholesterol and low‐density lipoprotein cholesterol (LDL‐C) contents decreased (p <.05). Moreover, dietary H. pluvialis improved the complement and immunoglobulin (Ig) contents, and lysozyme (LYZ) activities (p <.05). After challenge with V. harveyi, the survival rate in T2, T3, T4 and T5 was significantly higher than that of control, and the highest survival rate was in T3 (p <.05). These results indicated that dietary supplementation with the suitable level (0.4%–0.6%) of H. pluvialis could promote growth performance and hepatic antioxidant capacity, and enhance immune responses and resistance to V. harveyi challenge of L. maculates. [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the effects of dietary sodium butyrate on growth performance, intestine enzyme activities and intestinal proliferation‐related gene expression of juvenile golden pompano Trachinotus ovatus. A basal diet was supplemented with sodium butyrate at 0.0 (control), 0.25, 0.5, 1, 2 and 4 g/kg feed for 8 weeks. The final body weight, weight gain (WG), specific growth rate (SGR) and condition factor (CF) increased with increasing dietary sodium butyrate up to 2.0 g/kg, and thereafter declined, while feed conversion ratio exhibited an opposite trend. Compared with the control, the 2.0 g/kg sodium butyrate group had higher condition factor (CF) significantly (p < 0.05). Whole body ash decreased with increasing dietary sodium butyrate level, with the lowest whole body ash content in 4.0 g/kg sodium butyrate (p < 0.05). Compared with the control, the 2.0 g/kg sodium butyrate group had significantly increased plasma glucose, cholesterol, albumin level, A/G ratio, ALT and AST contents (p < 0.05), while significantly decreased plasma ALT/AST ratio (p < 0.05). As for the intestinal digestive and brush border enzymes activities, compared with the control, the 2.0 and 4.0 g/kg sodium butyrate groups had significantly increased intestinal protease, amylase, AKP and Na+‐K+‐ATPase activities (p < 0.05), respectively. The relative level of intestinal CDX2 mRNA of fish significantly increased with dietary sodium butyrate level. Compared with the control, the 2.0 g/kg sodium butyrate groups had significantly increased the expression of intestinal CDX2 and CREB mRNA (p < 0.05), respectively. In conclusion, these results suggested that the optimum sodium butyrate level for juvenile golden pompano could be 2.0 g/kg of the diet. [ABSTRACT FROM AUTHOR]

In order to investigate the dietary vitamin B6 (VB6) requirement for juvenile golden pompano, an experiment of six different diets with six dietary VB6 levels (0, 3.75, 7.47, 10.6, 13.7 and 18.5 mg/kg) was conducted. The results indicated that the content of dietary VB6 significantly increased weight gain rate (WGR), specific growth rate (SGR) and feed conversion ratio (FCR; p < 0.05). Golden pompano fed diet containing 7.47 mg/kg VB6 achieved the maximum ALT, AST, GPx, hepatic VB6 concentrations as well as the minimum MDA, however, the ALT, AST, GPx and hepatic VB6 concentrations decreased while MDA increased with a further increase in dieatry VB6. The highest values of GR and POD occurred at the 10.6 and 13.7 mg/kg dietary VB6 (p < 0.05) respectively. A diet supplemented with 7.47 mg/kg VB6 increased intestinal Na+, K+‐ATPase, Chymotrypsin, γ‐glutamyl transpeptidase, creatine kinase and amylase activities (p < 0.05). The relative abundance of Tenericutes and Bacteroidetes decreased while Proteobacteria and Firmicutes improved with an increase in dietary VB6 levels up to 7.47 mg/kg. Quadratic regression analysis on WGR, hepatic VB6 concentrations, AST and ALT indicated that the optimum dietary VB6 levels for juvenile golden pompano were 8.84–9.28 mg/kg. [ABSTRACT FROM AUTHOR]

The article presents a study which aims at maximizing the replacement of fish meal with fermented soybean meal (FSM) in experimental diets for pompano or Trachinotus ovatus. The authors got FSM from Guangzhou Goshine Feed in Guangzhou, China, and used floating cages during the growth trial to maintain the optimum dissolved oxygen level. The authors found out that experimental diets resulted to a quick feeding response and demonstrated good survival of pompano.

Apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, phosphorus (P), essential amino acids (EAA), non-essential amino acids (NEAA) and fatty acids were determined for white shrimp (Litopenaeus vannamei). A probiotic (Bacillussp.) was used at 0% (diet 1), 0.5% (diet 2), 1.0% (diet 3), 3.0% (diet 4) and 5.0% (diet 5) inclusion rates in experiment diets. Apparent digestibility coefficients was determined using 0.01% Y2O3 as an indicator. A total of 300 shrimp (initial mean body weight 11.5±0.6 g) were randomly stocked into fifteen 500-L outdoor concrete tanks. Faeces were collected from three replicate groups of shrimp three times a day. The ADCs of five diets were: DM, 66.1–69.6%; CP, 80.4–84.7%; lipid, 82.2–84.9%; P, 25.4–28.5%; EAA, 82.0–85.4%; NEAA, 81.5–85.1%; saturated fatty acids (SFA), 79.6–82.4%; monounsaturates (MUFA), 81.6–84.2% and polyunsaturates (PUFA)+highly unsaturates (HUFA), 83.4–86.6%. Apparent digestibility coefficients of DM, CP, lipid, P, amino acids and fatty acids in diet 1 were significantly lower than in other diets (P<0.05). Apparent digestibility coefficient of P in diets increased as probiotic increased. Apparent digestibility coefficient of lipid in diet 3 was the highest, but the difference was not significant among diets. In general, ADCs of most amino acids and fatty acids were over 80% in all diets, and PUFA+HUFA>MUFA>SFA. The results showed that ADCs of diets supplemented with 10, 30 and 50 g probiotic kg−1 basal diet were higher than in other diets except lipid, and the difference was significant. [ABSTRACT FROM AUTHOR]

Abstract Interleukins are critical cytokines that are ubiquitously present in both vertebrates and invertebrates and constitute the front line of host innate immunity. Here, we identified and analyzed IL-12p40 from the Chinese sea bass Lateolabrax maculatus (LmIL-12p40). The LmIL-12p40 gene is expressed as a 1386-base pair transcript that encodes a polypeptide of 321 amino acids. Transcriptional expression analysis indicated that LmIL-12p40 mRNA was ubiquitously expressed in all tested tissues and had a comparatively high expression level in immune-associated tissues (head-kidney and intestines). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) experiments showed that, after Vibro harveyi and Streptococus agalactiae infection, LmIL-12p40 mRNA expression was significantly up-regulated in the spleen, liver and head-kidney. To further clarify the immune function of LmIL-12p40 after bacterial challenge, the recombinant LmIL-12p40 protein was acquired using a prokaryotic expression method. Furthermore, the LmIL-12p40 dimer (LmIL-12p80) could be produced via protein–protein interactions by incubating p40 monomer expressed from the pET28a vector (pET28a-LmIL-12p40) with p40 monomer expressed from the pGEX4T-1 vector (pGEX4T-1-LmIL-12p40). The antimicrobial activity of the purified LmIL-12p40 and LmIL-12p80 proteins were further studied in vitro using a bacterial growth inhibition test (for both liquid and solid cultures) and in vivo (using a bacterial growth inhibition test with the head-kidney tissues). Furthermore, BL21 (DE3) E. coli cells transformed with the recombinant pET28a-LmIL-12p40 vector were dramatically protected in response to metal toxicity and H 2 O 2 -related oxidative stress. In summary, this study will provide foundational information regarding the role of LmIL-12p40 in defending against various biotic and abiotic stresses in fishes, which should help to further clarify the functional mechanism of interleukins. Highlights • Here, we identified IL-12p40 from the sea bass Lateolabrax maculatus (LmIL-12p40). • Bacterial infection upregulated LmIL-12p40 in the spleen, liver, and head-kidney. • LmIL-12p40 monomer and the LmIL-12p80 dimer showed antibacterial activities. • LmIL-12p40 protected E. coli from metal toxicity and H 2 O 2 -related oxidative stress. [ABSTRACT FROM AUTHOR]