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A high-performance liquid chromatography – fluorescence detection (HPLC-FLD) method was established for the determination of piperazine residues in whole eggs, albumen, and yolk employing pre-column derivatization with dansyl chloride. The egg samples were treated by accelerated solvent extraction (ASE) and the analytes purified by solid phase extraction (SPE). Acetonitrile/ultrapure water was used as the mobile phase for gradient elution. The linear dynamic range was from 6.80 to 200.0 µg/kg for whole eggs, 7.50 to 200.0 µg/kg for albumen, and 6.50 to 200.0 µg/kg for yolk with coefficients of determination (R2) greater than or equal to 0.9992. The average recoveries of piperazine from egg samples were from 72.86 to 89.26% when the concentrations were equal to the limit of quantification, 0.5 times the maximum residue limit, equal to the maximum residue limit, and twice the maximum residue limits. The relative standard deviations were between 1.73 and 4.99%. The limits of detection of piperazine in eggs were from 1.92 to 2.50 µg/kg, and the limits of quantification were between 6.50 and 7.50 µg/kg. The method meets the requirements of the European Union, the Ministry of Agriculture of the People's Republic of China and the U.S. Food and Drug Administration (FDA) for the determination of veterinary drug residues. The validated HPLC-FLD method was successfully applied to the determination of piperazine residues in 50 eggs purchased from local supermarkets. [ABSTRACT FROM AUTHOR]

Eggs were used to study the determination and depletion of amoxicillin (AMO) residues after oral dosing hens (25.0 mg kg–1, 50.0 mg kg–1body weight), once daily for five days. A reverse-phase high-performance liquid chromatography with fluorescence detection (RP-HPLC-FLD) method was developed to determine AMO residues in albumen, yolk and whole egg. By using pre-column derivatisation, an improved liquid–liquid extraction procedure was developed for sample preparation. AMO were extracted from eggs with acetonitrile. The extract solution was extracted using saturated methylene chloride. The supernatant was reacted with salicylaldehyde under acidic and heating conditions. Limits of detection (LODs) were 1.2 ng g–1and limits of quantification (LOQs) were 3.9 ng g–1for AMO. Recoveries of AMO from samples fortified at levels of 5.0–125.0 ng g–1ranged from 79.1% to 88.5% in albumen, 78.6–83.6% in yolk and 78.3–85.1% in whole egg, with coefficients of variation of ≤7.3%. The maximum concentrations of AMO in albumen, yolk and whole egg were found to occur at 1.5, 2.5, 1.5 days after withdrawal of medication respectively. AMO was not detectable in albumen at 7.5 days after final administration of AMO, at 10.5–11.5 days in yolk and 10.5 days in whole egg after administration of two oral doses. The method was applied during the residue study of AMO in order to formulate a reasonable withdrawal period to ensure food safety. [ABSTRACT FROM AUTHOR]

Myostatin, or growth and differentiation factor 8, is a member of the transforming growth factor-β superfamily; it functions as a negative regulator of skeletal muscle development and growth in mammals. In this study, single nucleotide polymorphisms in the 5′ regulatory region and exon 1 of the myostatin gene were detected by PCR–SSCP in the Bian, Jinghai, Youxi, and Arbor Acre chickens, and the associations of the polymorphisms with reproduction traits were analyzed. Seven SNPs (A326G, C334G, C1346T, G1375A, A1473G, G1491A, and G2283A) were found in the myostatin gene. Association analysis showed that the G2283A were significantly associated with reproduction traits. Bian chickens of the GG genotype had a greater age at first egg than those of the GA and AA genotypes (P < 0.01). Correspondingly, Bian chickens of the GA and AA genotypes had larger egg number at 300 days than those of the GG genotype (P < 0.05 and P < 0.01, respectively). Bian chickens of the AA genotype had significantly higher body weight at 300 days than those of the GG genotype (P < 0.05). These results suggested that the myostatin gene may have certain effects on reproduction traits other than merely as a negative regulator of skeletal muscle development and growth in mammals previously reported. [ABSTRACT FROM PUBLISHER]