Depletion of tilmicosin residue in Gushi chickens following oral administration via drinking water

Abstract

This study aimed to examine the depletion of tilmicosin residues in Gushi chickens following the administration at a concentration of 75 mg/L in their drinking water for three consecutive days. Plasma, liver, kidney, lung, muscle, and skin + fat samples were collected from 6 chickens at 6 h, 1, 3, 5, and 7 days after the treatment. Tilmicosin concentrations in the samples were determined using a high‐performance liquid chromatography (HPLC) method. The findings revealed that the highest tilmicosin residues were detected in the liver, followed by the kidney, lung, skin + fat, muscle, and plasma. Notably, at 7 days post‐treatment, no drug residue was detected in all samples except for the liver and kidney. The non‐compartmental model was employed to calculate relevant pharmacokinetic parameters. The elimination half‐lives (t1/2λz) of tilmicosin were as follows, ranked from long to short: skin + fat (45.42 h), liver (44.17 h), kidney (40.06 h), plasma (37.64 h), lung (31.39 h), and muscle (30.05 h). Considering the current residue depletion and the maximum residue limits (MRLs) set by Chinese regulatory authorities, the withdrawal times for tilmicosin were estimated as 18.91, 10.81, and 8.58 days in the kidney, liver, and skin + fat, respectively. A rounded‐up value of 19 days was selected as the conclusive withdrawal time. Furthermore, based on the observed tilmicosin concentrations in plasma and lung, combined with previously reported minimum inhibitory concentration (MIC) values against Mycoplasma gallisepticum, the current dosing regimen was deemed adequate for treating Mycoplasma gallisepticum infections in Gushi chickens.

In vitro antibacterial activity of danofloxacin against Escherichia coli in Gushi chickens and its residue depletion following multiple oral administration

“…Despite the relatively low plasma concentration, it is crucial to recognize that, in disease treatment, the focus should not solely be on blood drug concentration. The concentration of antibiotics at the local infection site plays a critical role in determining the therapeutic efficacy of infectious diseases ( Zhang et al, 2023 ). Escherichia coli , a susceptible bacterium in the intestine, and Mycoplasma , which can cause lung lesions, underscore the significance of site-specific considerations ( Collingwood et al, 2014 ; Wang et al, 2022 ).…”

“…Chicken is the primary component of poultry meat, making up over 60%. In China, it stands as a major meat product, witnessing a consistent year-over-year increase in consumption, ultimately becoming the second-largest meat consumer product ( Guo et al, 2023 ; Zhang et al, 2023 ).…”

“…Gushi chicken is renowned for its superior meat and egg quality and is a popular backyard chicken breed in China ( Zhai et al, 2023 ). It possesses exceptional qualities such as remarkable resistance to coarse feeding, robust disease resistance, and the delectable quality of its meat ( Zhang et al, 2023 ). In contrast to commercially farmed chickens confined in cages, Gushi chickens are bred under a free-range model that makes them highly vulnerable to widespread infections, such as Mycoplasma and Escherichia coli infections ( Chen et al, 2023 ).…”