Performance Of Nurserying Litopenaeus Vannamei Post-larvae In The BFT System Enriched With Rhizoma Coptidis

This experiment was based on the BFT culture system of Litopenaeus vannamei,adding different concentrations of Chinese herb Rhizoma coptidis,to explore the effects of Chinese herb Rhizoma coptidis on the growth,survival,anti-vibrio,digestive and immune enzyme activities of Litopenaeus vannamei post-larvae,as well as the effects on the nitrification performance of biofloc.This experiment aims to study the application of Chinese herbal Rhizoma coptidis in BFT nursering of Litopenaeus vannamei post-larvae and provide reference for production activity.My experiment was divided into the following three parts:1.Effects of different Rhizoma coptidis concentrations on nitrification enzyme activity and ammonia nitrogen conversion rate of biofloc.In order to explore the effects of different concentrations of Rhizoma coptidis on the ammonia nitrogen conversion rate and nitrification enzyme activity of bioflocs,the addition of 0 g/L,2 g/L,4 g/L and 6 g/L Rhizoma coptidis were named as control group C,treatment group T1,T2 and T3,respectively.The treatment group’s total ammonia nitrogen elimination rate was higher than the control group’s(0.38±0.07)mg/g.h),T1 group was the highest(1.49±0.08 mg/g h);The nitrite removal rate in T1 group(1.38±0.10 mg/g h)and T2 group(2.05±0.14 mg/g ·h)was higher than that in C group(0.75±0.06 mg/g h),and that in T3 group(0.17 ±0.05 mg/g h)was the lowest.In comparison to the control group,the treatment group’s total suspended solid was lower,and the content of total suspended solid in the water body tended to decrease with the increase of Rhizoma coptidis concentration,and the T3 group(363.33±40.41 mg/L)was the lowest.The experimental results showed that Rhizoma coptidis could improve the conversion rate of ammonia nitrogen in biofloc,improve the efficiency of ammonia nitrogen treatment in BFT system,reduce the accumulation of total suspended solid,improve the nitrification performance,the treatment capacity of solid organic particles and the utilization rate of solid organic particles.2.Effects of different concentrations of Rhizoma coptidis on total suspended solid,nutrient components and bacteriostatic ability of water in BFT systemThis experiment investigated the effects of adding different concentrations of Rhizoma coptidis to the BFT system on total suspended solid,nutrient components and bacteriostatic ability of water in BFT system.Adding 0 g/L,2 g/L,4 g/L and 6 g/L Rhizoma coptidis were named group K0,group K2,group K4 and group K6,respectively.The results showed that the total suspended solid in Rhizoma coptidis group were lower than control group’s significantly.Crude protein content in K2 group(44.61±0.77 %)and K6 group(43.57±0.29 %)was significantly lower than that in K0group(46.33±0.15 %)and K4 group(46.73±1.15 %),but there was no significant difference with K0 group.Compared with K0 group,the crude ash content of K4 group(16.85±4.04 %)was significantly decreased,and the crude ash content of K2 group(22.81± 0.66 %)and K6 group(22.37±0.80 %)was higher than that of K0 group(19.38±0.38 %),but there was no significant difference.Rhizoma coptidis treatment group had considerably less crude fat than the control group,and was as follows: K0group(8.80 ±0.15 %),K2 group(6.06 ±0.68 %),K4 group(6.76 ±0.29%)and K6group(6.00 ± 0.14%),respectively.In the bacteriostatic test,the number of Vibrio parahemolyticus in each group gradually decreased,and the control group maintained at103 CFU/ml,and the three Rhizoma coptidis treatment groups all decreased to zero.Among them,the number of Vibrio parahaemolyticus in group K4 decreased to zero the fastest.The results showed that adding Rhizoma coptidis could promote the inhibition to Vibrio parahaemolyticus of biofloc.The addition of Rhizoma coptidis can reduce the nutrient content of biofloc,and the loss of nutrient component of biofloc is small at the addition concentration of 4 g/L.3.Effects of Rhizoma coptidis at different concentrations on growth,digestive enzyme and immune enzyme activities and vibrio resistance of Litopenaeus vannamei.Disease has historically played a significant role in limiting the growth of the shrimp farming industry,and conventional shrimp rearing methods frequently involve antibiotics and other chemicals to cure diseases,particularly those brought on by Vibrio strains.The use of antibiotics over an extended period of time,however,will negatively impact their mode of action and cause bacterial resistance.In the present study,the effects of adding Rhizoma coptidis(R.coptidis)to the biofloc Litopenaeus vannamei(L.vannamei)shrimp culture system on water quality,biofloc nitrification performance,growth,digestive enzymes and immune factor activities,and anti-Vibrio bacteria of L.vannamei shrimp were investigated.R.coptidis(dry weight)was added in groups A (control),B,C,and D at concentrations of 0 g/L,2 g/L,4 g/L,and 6 g/L,respectively.The results showed that the experimental bioflocs nitrase and dehydrogenase groups performed better than those in the control group in terms of ammonia nitrogen oxidation rate and nitrous oxidation rate,respectively.Shrimp in the experimental group had greater body length,body weight,survival rate,weight gain rate,and specific growth rate than shrimp in the control group,and their food conversion ratio was lower.Shrimp digestion and immune enzyme analysis revealed that the experimental group performed better than the control group,and that the C group was the best.The mortality rate for the C and D groups in the Vibrio infection test was less than 50%,while the A group saw the earliest death and had a mortality rate of 100%.In addition to improving the rate at which organic matter decomposes by biofloc,the addition of R.coptidis has no detrimental effects on the water quality.It also benefits growth,digestive immunity,and anti-Vibrio ability of L.vannamei;the ideal addition concentration is 4 g/L.