| Oxytetracycline is a broad-spectrum antibiotic produced by Streptomyces,because of the role to improve the growth and treatment of disease, widely used infeed additives, commonly used drugs for the prevention and treatment of sick livestock,long-term abuse makes oxytetracycline residues in animal tissues exceeding the directharm to human health.In this experiment, one day old chicks as experiment object，on the age of40,single-factor completely randomized design of four-level test, the experiment animalswere divided into four groups, control group, low dose group (20mg/kg.bw.d),themedium dose group (50mg/kg.bw.d) and the high dose group (400mg/kg.bw.d), inaccordance with the design dose for seven consecutive days in the diets supplementedwith oxytetracycline, mixed feeding to oral administration. Chicken weight gain rateby determination of the administration, Nutrients and oxytetracycline residues inmuscle, the study of oxytetracycline residues in chicken eliminate muscle nutritionelements of rules and a different residue levels for veterinary drugs reasonable residualstandard formulation, risk assessment and prediction to provide a scientific basis.1.The method of oxytetracycline residues in chicken by high performance liquidchromatography was established for studying residue eliminate of oxytetracycline inthe muscle tissue.High Performance Liquid Chromatographic conditions: mobile phase0.01mol/L trifluoroacetic acid-acetonitrile (80:20, v/v) the column temperature30℃,the injection volume50μl, detection wavelength350nm, flow rate1ml/min. Thelimit of detection was8μg/kg, limit of quantification was18μg/kg, recoveries ratebetween90.2%and107.8%, coefficient of variation were less than10%, in line withthe requirements of residue detection. Multiple oral administration of oxytetracyclineresidues in muscle tissue in the elimination of the results showed that: the drugconcentration of oxytetracycline in the chicken-time curves correspond to an absorption one-compartment model and pharmacokinetic parameters (pharmacokineticparameters) as follows: absorption rate constant (Ka) of0.017h-1, elimination rateconstant (Ke) and0.009h-1, absorption half-life (T1/2Ka)40.1h and74.1h, eliminationhalf-life (T1/2Ke), time to peak (Tmax)77.5h, peak plasma concentration (peakconcentration, Cmax) of157.2μg/kg, the area under the curve (area under the timeconcentration curve to AUC) was34686μg*h/kg. Oxytetracycline in the chicken invivo drug activity manifested as rapid absorption, extensive tissue distribution,eliminate slow.2.Four groups of chickens in accordance with the design dose oral administrationof mixed feeding oxytetracycline measured before drug administration and for7dafter the chicken body weight, calculate the weight gain rate, the results show that: thecontrol group, low-dose group, middle dose group and high dose group chicken weightgain rate:25.5%,32.6%,35.9%and17.8%. Low dose and middle dose groupchicken weight increase rate higher than that in the control group, the difference wasextremely significant (P<0.01), oxytetracycline showed significant growth promotingeffect, chicken weight gain of high-dose group than the control group with the controlgroup significantly different (P<0.05), high doses of oxytetracycline showed somegrowth inhibition.3.Four groups of chickens according to the design dose for seven consecutivedays of oral mixed feeding oxytetracycline, respectively, in the administration2d,4d,6d,8d,11d,13d,15d,18d and20d taked chicken breast muscle, determination ofthe muscles of crude protein, crude fat and mineral element content andoxytetracycline residues. The results showed that: the protein content was higher in thelow dose and middle dose group of muscles, the difference was significant (P<0.01),while the protein content of the high dose group is lower than the control group(P<0.05), oxytetracycline residues protein content; muscle changes in fat content andprotein and fat content higher than that in the control group of low-dose and middledose group, significant difference (P<0.01), the fat content of the high dose group thanthe control group, the difference was significant (P<0.05); mineral element contents,five kinds of mineral elements of the muscle containing oxytetracycline group, copper(Cu), iron (Fe), magnesium (Mg), zinc (Zn), calcium (Ca) decreased to some extent, copper, low-dose and middle dose group did not change significantly, the differencewas not significant (P>0.05), high dose group was significantly (P<0.01); for iron,low-dose group than the control group no significant difference (P>0.05), middle doseand high dose group and the control group compared to the difference very significant(P<0.01); zinc content in the muscle, among the high dose group differences verysignificantly with the outside (P<0.01). no significant changes in other dose groups(P>0.05); the magnesium content in the muscle, in the dose and high dose groupcompared with control group significant difference (P<0.01), low-dose group, nosignificant change (P>0.05); muscle calcium content in the treatment group comparedwith the control group the difference was significant (P<0.01).4. Oxytetracycline residues in muscle as the independent variable, the content ofeach nutrient content as the dependent variable, take regression analysis, the fittedregression equation results show that: the quadratic curve fitting equation for themathematical model, the correlation coefficients were greater than0.8level ofsignificance (P<0.05), fitting high. Growth promoting effect of low doseoxytetracycline continue to increase the dosage, the growth promoting effect was notobvious, and continue to increase with the dosage, oxytetracycline performancegradually inhibited it; show that the variation of mineral elements in oxytetracyclinecalcium and magnesium content of these five elements. With the elimination ofoxytetracycline, the nutrients levels of each dose group approaches, showed thatoxytetracycline influence weakened.Oxytetracycline residue detection method established in this study, the detectionlimit, method of operation is simple, reproducible, suitable for the monitoring ofoxytetracycline residues in food of animal origin, to establish the mathematical modelof oxytetracycline residue levels on chicken meat nutrient elements, the safety ofchicken consumption, safe use of oxytetracycline in the chicken feed, and provide ascientific basis, has a higher theoretical value and a good prospect. |
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