Safety Evaluation Of Apramycin Sulphate In Litopenaeus Vannamei

This thesis was conducted to investigate the security of Apramycin sulphate to Litopenaeus vannamei. It contains four sections:(1) Inhibition of Apramycin sulphate on Aeromonas hydrophila in vitro.(2) The acute and subacute toxicity of Apramycin sulphate for Litopenaeus vannamei.(3) Effects of Apramycin sulphate on the growth performance, serum biochemical indices, intestinal microflora, non-specific immune indicators, resistance against Aeromonas hydrophia of Litopenaeus vannamei, tissue histological structure and the residues in the tissue.(4) The elimination of Apramycin sulphate in hepatopancreas and muscle. The mainresults are as follows:1. Inhibition of Apramycin sulphate on Aeromonas hydrophila in vitroThe results showed that MIC, MBC and MBC/MIC of Apramycin sulphate were0.5,1.0μg/mL and2, respectively. It inhibited the growth of Aeromonas hydrophila at lag phase. It was concentration-dependent according to the killing curve and PAE. The maximum drug action of Apramycin sulphase appeared at the stationary phase, and the PAE of Aeromonas hydrophila was conspicuous in vitro. The rate of drug resistance obtained in Aeromonas hydrophila against Apramycin sulphate doubled in the10days subculture.2. The acute and subacute toxicity of Apramycin sulphate for Litopenaeus vannamei.Shrimps with a body weight of4.0-5.0g were immersed with Apramycin sulphate. The concentration of Aramycin sulphate was0,0.1,1.0,10and100mg/L. At96th h immersion, the survival rate in100mg/L group was93.3%.240shrimps with a body weight of (1.01±0.01) g were randomly divided into4groups and fed respectively a control diet and3diets added with300,1500and3000mg/kg Apramycin sulphate for28days. The results showed that at28th d, HSI and serum ALT activities in addition groups were significantly higher than those in the control (P<0.05). The addition of300mg/kg Apramycin sulphate led to swelling, denaturation and exfloliation of hepatic absorptive cell and secreting cells, and it also caused vacuolar degeneration and connective tissue hyperplssia. With the increasing of Apramycin sulphate, the symptoms became more serious. Apramycin sulphate had some toxic effects on intestine, which was concentration-dependent. Biotin deficiency resulted in denaturalization, mortification, and exfoliation of intestinal epithelium cells. It was replaced by inflammatory cells and connective tissue at last.3. Effects of Apramycin sulphate on the growth performance, serum biochemical indices, intestinal microflora, and resistance to Aeromonas hydrophila of Litopenaeus vannamei.960shrimps with a body weight of (0.51±0.01) gwere randomly divided into6groups and fed a basal diet and diets supplemented with60,120,180,240and300mg/kg Apramycin sulphate respectively, named G0, G60, G120, G180, G240and G300. After49d feeding, the results showed as follows:(1) G180and G240had higher weight gain rate (WGR) and protein efficiency ratio (PER) than those in GO (P<0.05). There was no significant difference (P>0.05) in survival rate (SR), feed intake (FI) and feed coefficient (FC) among all groups. Crude protein (CP) content in G240was significantly higher than that in GO (P<0.05). In comparison with G0, serum total protein (TP) and triglyceride (TG) content in G240increased significantly (P<0.05), while serum uric acid (UA) content decreased significantly (P<0.05).(2) In comparison with G0, the activities of serum POD, LZM, AKP and SOD among all treatments showed no significant difference (P>0.05), as same as AKP, LZM, SOD and ACP activities in hepatopancreas (P>0.05). ACP in serum and POD in hepatopancreas in G240was significantly higher than those in GO (P<0.05). With the increasing of Apramycin sulpate supplementation the number of total bacteria and Vibrio among all the treatments were tended to decrease. The number of Vibrio in G240and G300was significantly lower than that in GO (P<0.05). The number of total bacteria in G300was significantly lower than that in GO (P<0.05). The number of Lactobacillus and Bifidobacterium was not significantly affected (P>0.05). After96h infection of Aeromonas hydrophila, the cumulative mortality rate in GO was86.7%, and that in the groups with Apramycin sulphate was from43.3%to66.7%. The relative percentage survival (RPS) was from23.1%to50.0%.(3) Significant histopathological changes of hepatopancreas and intestine in L. vannamei were observed in G180. Absorptive cell and secreting cells were swelling, denaturation and exfloliation vacuolar degeneration and connective tissue hyperplssia was found among tubules of hepatopancreas. Intestinal epithelium cells were denaturalization, mortification, and exfoliation, and replaced by inflammatory cells and connective tissue at last. The residues of Apramycin sulphate were detected to be2.92～19.11μg/g in hepatopancreas and0.91-8.20μg/g in muscle. Apramycin sulpate content in these two tissues significantly increased with the supplementation of Apramycin sulpate increased.5. The elimination of Apramycin sulphate in hepatopancreas and muscle of Litopennaus vannamei.Shrimps with a body weight of (0.47±0.01) g were randomly divided into4groups and fed a basal diet and diets supplemented with80,240and400mg/kg Apramycin sulphate respectively for28days. In the next28days, all the addition groups were fed with basal diet. The results showed that Apramycin sulpate content in these two tissues significantly increased with increasing of Apramycin sulpate. The residues of Apramycin sulphate in the muscle and hepatosomatic reduced with withdrawal time. At28th d, drug content in hepatopancreas was0.05(G80),0.13(G240) and0.31(G400) μg/g, and in muscle was0.10(G240),0.18(G400) μg/g.