Grass carp (Ctenopharyngodon idella) in ponds and cages in China.

2020 ◽  
Author(s):  
Yang Yi ◽  
Zong-wen Wu
Keyword(s):  
Grass Carp ◽  
Ctenopharyngodon Idella ◽  
Mixed Feed ◽  
Female Ratio ◽  
Commercial Feed ◽  
Grass Carp Ctenopharyngodon Idella ◽  
Supplementary Feed ◽  
Pellet Feed ◽  
Stocking Rates ◽  
Male To Female

Abstract In China, broodstock conditioning of grass carp (Ctenopharyngodon idella) is conducted in earthen ponds at a density of 2,250 - 3,000 kg ha-1 and at a male to female ratio of 1:1 or 1:1.25. Vegetation such as duckweed and rye grass and small amounts of farm-made or commercial feed are given. Nursing from fry to fingerlings (early nursing) is done in nursery ponds at a density of 1,500,000 - 2,250,000 fish ha-1 (150-225 m-2). After nursing for 20-30 days, the fish reach 3-4 cm in length and are released into fingerling nursery ponds for advanced nursing. Fingerlings are stocked in fingerling nursery ponds at a density of 3,250-4,000 fingerlings ha-1 (0.325-0.40 m-2). The main feed is pellet feed and grass. After 6 months of culture, the fish can reach 800 g. Then they are released into grow-out ponds or cages. Stocking rates for ponds are 1,650-2,000 fish ha-1 (0.165-0.20 m-2) and 50-80 fish m-2 for cages. Mixed feed is used as the main feed and grass is given as supplementary feed. The fish can reach 1.5-2.0 kg in 1 year and 3.5-5.0 kg in 2 years.

scholarly journals Oral Vaccination of Grass Carp (Ctenopharyngodon idella) with Baculovirus-Expressed Grass Carp Reovirus (GCRV) Proteins Induces Protective Immunity against GCRV Infection

Vaccines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 41
Author(s):  
Changyong Mu ◽  
Qiwang Zhong ◽  
Yan Meng ◽  
Yong Zhou ◽  
Nan Jiang ◽  
...  
Keyword(s):  
Survival Rate ◽  
Grass Carp ◽  
Oral Vaccine ◽  
Serum Antibody ◽  
Ctenopharyngodon Idella ◽  
Control Group ◽  
Oral Vaccination ◽  
Grass Carp Reovirus ◽  
Silkworm Pupae ◽  
Grass Carp Ctenopharyngodon Idella

The grass carp reovirus (GCRV) causes severe hemorrhagic disease with high mortality and leads to serious economic losses in the grass carp (Ctenopharyngodon idella) industry in China. Oral vaccine has been proven to be an effective method to provide protection against fish viruses. In this study, a recombinant baculovirus BmNPV-VP35-VP4 was generated to express VP35 and VP4 proteins from GCRV type Ⅱ via Bac-to-Bac baculovirus expression system. The expression of recombinant VP35-VP4 protein (rVP35-VP4) in Bombyx mori embryo cells (BmE) and silkworm pupae was confirmed by Western blotting and immunofluorescence assay (IFA) after infection with BmNPV-VP35-VP4. To vaccinate the grass carp by oral route, the silkworm pupae expressing the rVP35-VP4 proteins were converted into a powder after freeze-drying, added to artificial feed at 5% and fed to grass carp (18 ± 1.5 g) for six weeks, and the immune response and protective efficacy in grass carp after oral vaccination trial was thoroughly investigated. This included blood cell counting and classification, serum antibody titer detection, immune-related gene expression and the relative percent survival rate in immunized grass carp. The results of blood cell counts show that the number of white blood cells in the peripheral blood of immunized grass carp increased significantly from 14 to 28 days post-immunization (dpi). The differential leukocyte count of neutrophils and monocytes were significantly higher than those in the control group at 14 dpi. Additionally, the number of lymphocytes increased significantly and reached a peak at 28 dpi. The serum antibody levels were significantly increased at Day 14 and continued until 42 days post-vaccination. The mRNA expression levels of immune-related genes (IFN-1, TLR22, IL-1β, MHC I, Mx and IgM) were significantly upregulated in liver, spleen, kidney and hindgut after immunization. Four weeks post-immunization, fish were challenged with virulent GCRV by intraperitoneal injection. The results of this challenge study show that orally immunized group exhibited a survival rate of 60% and relative percent survival (RPS) of 56%, whereas the control group had a survival rate of 13% and RPS of 4%. Taken together, our results demonstrate that the silkworm pupae powder containing baculovirus-expressed VP35-VP4 proteins could induce both non-specific and specific immune responses and protect grass carp against GCRV infection, suggesting it could be used as an oral vaccine.

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