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SummaryPavlova, I., 2015. Effect of probiotics on doxycycline disposition in gastro-intestinal tract of poultry. Bulg. J. Vet. Med., 18, No 3,[248][249][250][251][252][253][254][255][256][257] Poultry feed is often supplemented with probiotics in order to improve disease resistance and growth performance and to decrease undesirable effects of antibacterial therapy. Therefore this study was designed to evaluate the effect of probiotics such as Lactobacillus brevis, L. plantarum and L. bulgaricus on pharmacokinetics of doxycycline in healthy DUC broiler chickens. The treatment with doxycycline at a dose of 10 mg/kg body weight started on the 15 th day after hatching for 5 days via drinking water. The probiotics treated group received Lactobacillus strains for 15 days, 5 days after hatching. Treatment with probiotics did not lead to statistically significant differences in serum concentrations of doxycycline between both groups of chickens. The value of C max was significantly higher in the liver of doxycycline + probiotics treated chickens (0.23±0.1 µg/g) than in doxycycline-treated group (0.19±0.17 µg/g). The same tendency was observed in the jejunum of both groups of animals suggesting favourable results in the cure of bacterial diseases of the gastrointestinal tract of poultry.The selected dose was appropriate for treatment of infections caused by pathogens with MIC < 0.25 µg/mL irrespective of antibiotic administration alone or in combination with probiotics. The simultaneous treatment of chickens with probiotics and doxycycline did not entail changes in the dose regime of the antibiotic.

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Macedonian Veterinary ReviewThe pharmacokinetics of doxycycline was investigated in force-fed and normally fed ducks after single intravenous (i.v.) and oral (p.o.) administration at a dose of 15 mg/kg bw. Serum concentrations of the drug were determined by the HPLC method. Pharmacokinetic parameters were calculated using compartmental analysis. Serum concentrations of doxycycline after i.v. administration in both groups were not statistically different. The values of half-lives were 5.82±1.85 h and 6.06±5.51 h in normal and force-fed birds. The total body clearance was respectively 0.40±0.05 L/h/kg and 0.34±0.10 L/h/kg, and volume of distribution (V ss ) was 2.80±0.85 L/kg and 2.18±0.89 L/kg. After p.o. administraton the maximum serum levels in the control group were 0.70±0.12 μg/mL and in force-fed birds were 1.93±0.32 μg/mL, measured at 2.95±0.60 h and 1.45±0.24 h, respectively. The values of absolute bioavailability were 18.89±6.48% and 37.58±13.63%. Longer doxycycline retention in force-fed ducks was registered. Our data can be accepted as an information for possible prolonged retention of doxycycline in force fed ducks compared to normally fed ones.

Abstract. The study was conducted with 224 domestic quails from the specialized meat-type WG line. The duration of fattening period and sex on productive traits, slaughter traits and meat quality of quails was evaluated. The study has shown that the longer duration of the fattening period in quails from the meat-type line WG was associated with lower production efficiency, with more reduction after the 35th day of life. The production efficiency in male quails was lower compared to that in females. The dispersion analysis demonstrated that the determination of 72.2% and 69.6% of dressed carcass weight and deboned meat weight, respectively, depended on fattening period duration (p<0.001). When fattening increased from 28 to 42 days, the amount of feed necessary for one bird increased by 73% and 87%, corresponding to increased costs by 64.5% and 77%. For production of 1 kg dressed quail carcasses, the necessary feed increased by 42.3-45.8% on a weight basis and by 35-37.7% on a cost basis. For production of 1 kg deboned quail meat, corresponding increases are by 42.1-49.5% and 34.8-41.2%, respectively. The period between 28 and 35 days of age was the most appropriate for planning slaughter of WG quails. During that period, the economic efficiency, although already declining, was still within acceptable limits and the increase in quantitative traits in both sexes – still relevant, making the produce more attractive for consumers. With age, the changes in colour characteristics of M. pectoralis superficialis result in darkening of meat (p<0.001). Thus, it assumes nuances specific rather for game meat. This effect is desirable, as it improves the commercial presentation of domestic quail meat in line with consumers’ attitudes.