Search

This study measured the concentrations of salbutamol residues in red and white hair of cattle during and after salbutamol administration. Three Chinese Simmental beef cattle received an oral administration of 150 µg/kg body weight/d salbutamol for 21 consecutive days. Salbutamol concentrations were determined on Days 1, 7, 14, and 21 of administration and on Days 7, 14, 28, 42, and 70 following the last administration dose using ultra-performance liquid chromatography-tandem mass spectrometry. The concentrations of salbutamol that eluted from hair were determined. The results revealed that salbutamol concentrations were higher in red hair than in white hair on the same sampling day (P < 0.01). In red hair, salbutamol concentrations increased from 29.82 ± 1.8 ng/g on Day 1 of administration to 442.55 ± 250.29 ng/g on Day 21 of administration, and decreased to 33.36 ± 19.22 ng/g on Day 70 after the last administration. In white hair, salbutamol concentrations changed from 4.25 ± 0.32 ng/g on Day 1 of administration to 33.81 ± 6.44 ng/g and 12.25 ± 2.51 ng/g on Days 14 and 70, respectively, after the last administration. The concentrations of salbutamol that eluted from white hair on Days 1 and 7 were 22.94 ± 2.00 ng/g and 92.94 ± 22.49 ng/g, respectively. Our findings revealed that hair is an appropriate biological matrix for assessing the illegal use of salbutamol in animal husbandry. [ABSTRACT FROM AUTHOR]

Ractopamine was approved by the US Food and Drug Administration for use as a growth promoter on cattle a decade ago is still banned by the European Union and most Asian countries. While, ractopamine residues in living samples and some organs (besides liver, muscle and kidney) of cattle under the recommended feed condition (10-30 mg/kg in dry matter, 28-42 days) remains unclear. In this study, nine cattle (246.22 ± 18.17 kg) were fed 0.67mg/kg body weight (equivalent to 30mg/kg in dry matter) of ractopamine for 28 days to investigate the residues of ractopamine in plasma, urine and organs. Plasma and urine were sampled during treatment and withdrawal period. Three cattle were slaughtered on withdrawal days 0 and 3 for organs collection. Ractopamine was determined by LC-MS/MS and its glucuronide metabolites were identified by Q-TOF/MS. Ractopamine concentrations in plasma and urine reached highest on treatment day 14 (2.88 ng/mL) and day 7 (4713.25 ng/mL), respectively. On withdrawal day 28, ractopamine concentrations in plasma and urine and were undetectable (limit of quantitation, 0.2 ng/mL) and 4.21 ng/mL, respectively. On withdrawal day 0, ractopamine residue in tissues were as follows: liver > eye > lung > spleen > aqueous fluid > heart > bile > kidney > gluteus > rib eye muscle. Compared with those on withdrawal day 0, ractopamine contents in most tissues that sampled on withdrawal day 3 were lower (P < 0.05), while that in the eye tissues, aqueous fluid, and kidney were stable or higher. These results provide extensive data for risk management in ractopamine approved countries and monitoring of the illegal usage in countries that ban ractopamine. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the salbutamol residues in the plasma, urine and hair of heifers after a single dose. Three heifers were given a single oral dose of salbutamol hydrochloride (150 μg/kg bodyweight). The salbutamol concentrations were measured in the plasma, urine (before and after hydrolysis with β-glucuronidase/arylsulfatase) and hair samples with ultra-performance liquid chromatography-tandem mass spectrometry. In the unhydrolyzed samples, the peak concentrations of salbutamol occurred in the plasma and urine at 12 and 8 h after drug administration, respectively, butwere belowthe limit of quantification (LOQ = 0.2 ng/mL) at 48 and 120 h after administration, respectively. However, in the hydrolyzed samples, the salbutamol concentration was 1.1 ng/mL in the plasma 72 h after its administration and 0.7 ng/mL in the urine 168 h after its administration. Thus, the concentrations of salbutamol were significantly higher in the hydrolyzed samples than that in the unhydrolyzed samples (P < 0.01). The concentrations of salbutamol in the black and white hair 24 h after its administration were 1.7 and 1.0 ng/g, respectively. These results indicate that hair may be a target tissue for detecting the misuse of salbutamol after a single dose and that the primary forms of salbutamol in the plasma and urine samples from heifers are its sulfate and glucuronide conjugates. [ABSTRACT FROM AUTHOR]

The objective of the present study was to assess the accumulation of ractopamine (RAC) residues in hair of Chinese Simmental beef cattle following exposure to two doses of RAC for 28 days. Six male cattle were orally administered with RAC hydrochloride at a dose of 0.67 mg/kg body weight/day (low-dose group, n = 3) and 2.01 mg/kg body weight/day (high-dose group, n = 3). The results suggested that RAC was obviously accumulated in hair, with a concentration of 5.57 ± 0.66 ng/g (white hair) and 13.67 ± 2.73 ng/g (red hair) in the low-dose group on Day 1 of treatment, respectively. In red hair, the peak concentrations of RAC were 5619.38 ± 2156.84 ng/g (low-dose group) and 6908.3 ± 1177.62 ng/g (high-dose group) on Day 14 of treatment, and then decreased slowly. In white hair, the highest concentrations of RAC were 3387.38 ± 1620.87 ng/g (low-dose group) on Day 14 of withdraw and 9621.72 ± 1497.65 ng/g (high-dose group) on Day 28 of treatment. The concentration of RAC in old hair was higher than that in new hair. No significant differences in RAC concentrations were obtained among dosage, hair color and old versus new hair (P > 0.05). The results indicated that ractopamine is significantly accumulated in red and white hair of Chinese Simmental beef cattle, which can be used as a matrix to assess the presence of RAC residues. [ABSTRACT FROM AUTHOR]

We aimed to evaluate whether living tissues such as urine, plasma and hair were suitable for monitoring clenbuterol (CL) abuse after its subchronic administration of a growth-promoting dose to the Chinese Simmental beef cattle. Eight male, white and red pied Chinese Simmental beef cattle were involved in the experiment, and the CL dose was 16 μg/kg BW/day. Liquid chromatography tandem mass spectrometry (LC-MS-MS) was used to determine CL residues in different tissues, and the addition of D9-clenbuterol internal standard was applied to increase determination accuracy. The recovery of plasma, urine, hair and in vivo tissues was 88.5-114.2, 83.9-114.3, 88.6-116.9 and 85.3-121.7%, respectively. The results showed that CL residue concentrations in the plasma, on Days 14 after withdrawal and later, were lower than the limit of detection (LOD) (0.06 ng/mL) and CL residue in urine was lower than LOD (0.16 ng/mL) 42 days after treatment. CL significantly accumulated in the white and red hair and maintained more than 7.19 ' 2.19 pg/mg within the early withdrawal period of 70 days. A large number of CL were determined in all tested biological tissues, in which residues were higher than the maximum residue limits (MRLs) after dietary administration of CL for 21 days and pre-slaughter withdrawal period of ~6 h. A particular concern is the slow depletion of residues of CL in some tissues like gluteus and liver still exceeding theirs MRLs, respectively, on Days 14 or 28 days after withdrawal. Our study indicated that plasma and urine could be available for monitoring CL abuse only within a short period of time. However, hair (including light-pigmented) as a target matrix can be selected to perform the long-period monitor of CL. [ABSTRACT FROM AUTHOR]