Investigation On The Security Of Quinocetone In Juvenile Sea Cucumber(Apostichopus Japonicus) Culture

Apostichopus japonicus belongs to Echinodermata and Holothuroidea, which has high nutritional and medical value. With the demand for it, the breeding industry has developed rapidly. The disease and death frequently happen during culturation,therefore, the rational use of veterinary drug is especially important. Quinocetone is the new developed types of quinoxalines in China, which was approved by ministry of agriculture as the antimicrobial promotor in pig feed in 2003. Quinocetone has obvious antibacterial and growth promoting effects on animals, and breaks through the limitation of traditional veterinary medicine. At present, quinocetone is widely used in chicken, duck and pig, it is also used in fishes, but the application in sea cucumber has not been reported.In order to investigate the using safety in juvenile sea cucumber(Apostichopus japonicus) breeding, the influence of quinocetone on growth performance, non-specific immunity and anti-stress ability of juvenile A. japonicus was researched in this paper.MQCA was identified as a metabolite of quinocetone in sea cucumber in this paper. To investigate the effects on the safety of sea cucumber products, the distribution and residue elimination of quinocetone and MQCA in A. japonicus was discussed in the paper.The results showed that quinocetone had a significant growth-promoting effect on A. japonicus, the weight growth rate(WGR), specific growth rate(SGR) and survival rate(SR) were higher than those of control groups. When quinocetone was 20 mg/kg in feed, the WGR, SGR and SR were significantly higher than those of other groups.Quinocetone showed an effective immune enhancement as it improved the SOD, AKP and ACP enzyme activities in the body wall of A. japonicus. The maximal value were documented when quinocetone was 20 mg/kg in feed. The difference between treatments and control decreased with time. The enzyme activities of SOD and ACP in treatments generally decreased to that of control in 50 days. The experiments indicatedthat high dosage of quinocetone(80-100 mg/kg in feed) reduced the anti-stress ability of juvenil A. japonicus. Thus, quinocetone at 20 mg/kg in feed was recommended during juvenile A. japonicus culture.The high performance liquid chromatography(HPLC) method was optimized for the determination of quinocetone. The samples were extracted by ethyl acetate, then purified with hexane. Quinocetone was separeted on an MG C18 column, using acetonitrile and water as mobile phase, and detected at wavelength of 312 nm. There was a good linear correlation in the range of 0.05 ~1.00 μg/m L. The linear regression equation was Y=5.41e+002 X+1.24e+002 with a correlation coefficient of 0.9995. At the spiked levels from 20 μg/kg to 100 μg/kg, the average recoveries were 75.9 ~ 86.2%,and the relative standard deviations were 3.15~6.48%. The method was simple and efficient, with high sensitivity and good reproducibility. The precision and accuracy could satisfy the requirement of residue analysis.The elimination of quinocetone in juvenile A. japonicus was studied in this article.The residue of quinocetone reached a very high value in juvenile A. japonicus just in one day, which showed that quinocetone was absorbed rapidly during the treatment.Then, the residual amount of quinocetone reduced slightly, and tended to be stable. The residual amount of quinocetone was approximately a linear function of the dosage. The quinocetone residual amount were below the detection limit in two days withdrawal time except for the 100 mg/kg group. The quinocetone residues in all the groups were below detection limit after four days withdrawal time. It was indicated that quinocetone was eliminated very fast, and it did not make impact on the safety of sea cucumber.It was confirmed that quinocetone can cause MQCA residue in A. japonicus. The MQCA was accumulated in A. japonicus, and the residue amount was approximately a linear function of the quinocetone dosage. The MQCA was eliminated extremely slow after the use of quinocetone. Forty-six days after the discontinuation, MQCA had a very slight decline. MQCA declined significantly in 246 days after the discontinuation, but still residue in A. japonicus. The MQCA residue had been completely eliminated in 403 days after the discontinuation. So it is suggested that quinocetone can be used only in the juvenile sea cucumber breeding. After more than one year, MQCA can be eliminated and have no impact on the safety of sea cucumber products.The residue of quinocetone in the viscera were higher than in the body wall. Theresidue of MQCA in the body wall were higher than in the viscera. MQCA can be accumulated in A. japonicus.