ABSTRACT:The aim of the study was to investigate acute toxicity of clove oil for common carp and, using values of haematological and biochemical profiles of blood and histological tissue examinations, to assess the effects of the fish exposure to that anaesthetic. Acute toxicity values of clove oil for carp were found 10 minLC50 74.3 mg/l; 10minLC0.1 51.6 mg/l; 10minLC99.9 110.1 mg/l; 96hLC50 18.10 mg/l; 96hLC0.1 15.45 mg/l; and 96hLC99.9 19.80 mg/l. The fish were divided into four groups for haematological and biochemical examinations of blood and histological examinations of tissues. The groups were Control I (before the anaesthetic administration), Experiment I (immediately after 10 min anaesthesia at the concentration of 30 mg/l), Experiment II (24 hrs after 10 min anaesthesia) and Control II (controls examined in parallel with Experiment II). A total of 40 carp were examined. Clove oil anaesthesia had not effect on the haematological profile. The 10-min exposure to clove oil at a concentration of 30 mg/l caused a significant (P < 0.01) increase in the concentration of glucose (GLU) and inorganic phosphate (PHOS) immediately after anaesthesia. Clove oil anaesthesia had not effect on other biochemical indices. Histological examination showed capillary ectasia of gill filaments immediately after clove oil anaesthesia. Twenty-four hours after anaesthesia, no ectasia was observed. No histopathological changes were demonstrated in other tissues following anaesthesia. Results of the examinations suggest that the use of clove oil at a concentration of 30 mg/l does not cause irreversible damage in carp.

Ecotoxicity and genotoxicity of widely used veterinary antimicrobials oxytetracycline and flumequine was studied with six model organisms (Vibrio fischeri, Pseudomonas putida, Pseudokirchneriella subcapitata, Lemna minor, Daphnia magna, Escherichia coli). Overall median effective concentration (EC50) values ranged from 0.22 mg/L to 86 mg/L. Pseudomonas putida was the most sensitive organism (EC50 values for 16-h growth inhibition were 0.22 and 0.82 mg/L for oxytetracycline and flumequine, respectively), followed by duckweed Lemna minor (7-d growth inhibition, EC50 2.1 and 3.0 mg/L) and green alga Pseudokirchneriella subcapitata (4-d growth inhibition, EC50 3.1 and 2.6 mg/L). The least sensitive organism was Daphnia magna (48-h immobilization, lowest-observed-effect concentration [LOEC] of oxytetracycline of 400 mg/L). Oxytetracycline showed limited genotoxicity (SOS-chromotest with Escherichia coli, minimal genotoxic concentration of 500 mg/L), and flumequine was genotoxic at 0.25 mg/L. Based on the reported measured concentrations (MECs) and predicted no-effect concentrations (PNECs), oxytetracycline may be concluded to be of ecotoxicological concern (calculated risk quotient = 8), whereas flumequine seems to represent lower risk.

The aim of the present study was to assess the effects of medicated feed, Rupin Special gran. ad us. vet. with oxytetracyclini chloridum as active ingredient (5 g·kg -1 feed), on physical and chemical characteristics of a pond ecosystem and the health of carp of two age groups in a pilot operation. The medicated feed was administered in 8 doses (15 g·kg -1 live weight). In the study, temperature, oxygen concentration, pH, microbiological, hydrobiological and hydrochemical variables of pond water were monitored. The fish health assessment was based on clinical, pathological-morphological and haematological examinations of 80 individuals in total. The examinations were made before, during, immediately after and 15 days after the administration of medicated feed. No effects on water quality were found. An important histological change after the application of 8 doses was the loss of haematopoietic tissue from the spleen, and dystrophic changes in the renal duct epithelium. A decrease in leukocyte and lymphocyte counts and in total blood plasma protein concentrations (P < 0.05) were observed already after the 3 rd dose of Rupin Special. It follows from the results of the study that Rupin Special should be used in only 4 (exceptionally 6) doses, compared to the originally recommended 8 doses. Fish treatment, haematology, histology, medicated feedFor the suppression and treatment of bacterial diseases in fish, an effective medication is required to which pathogenic microorganisms are sensitive. At present there are only two antibiotic preparations registered in the Czech Republic for application to fish. These are Flumiquil 50% plv. ad us. vet., a synthetic chinolon-based antibiotic with flumequin as an active ingredient, and Rupin Special gran. ad us vet., a tetracycline antibiotic with oxytetracycline (5 g·kg -1 ) as an active ingredient ( Koláfiová and Nepejchalová 2005).Rupin Special is a broad-spectrum antibiotic with activity against the majority of grampositive and gram-negative bacteria. Vitamin A (retinoli acetas) is present in the preparation mainly to improve the condition and resistance of the fish. Saccharin (saccharinum) and anise oil (anisi etheroleum) are added as taste correcting agents to guarantee that the feed is readily accepted by fish. Stabilizers and coating materials prevent undesirable changes in the preparation during its distribution or storage. Wheat flour is used as the vehicle of the preparation and this also increases the feed's nutritional value.Rupin Special is supplied in cylindrically shaped pellets about 3 -4 × 3-10 mm in size. The pellets are hard, and they soften when soaked in water, although they will retain their

Nepejchalová L., Z. Svobodová, J. Kolářová, K. Frgalová, J. Valová, D. Némethová: Oxytetracycline Assay in Pond Sediment. Acta Vet. Brno 2008, 77: 461-466.The fate of drug residues and their metabolites in the environment is relatively rarely investigated in the conditions of the Czech Republic, resulting in limited availability of scientific information.To demonstrate one example, we prepared a model study with medicated feedstuff containing oxytetracycline hydrochloride (OTC HCl), which was used in fish under normal conditions of use. The oxytetracycline (OTC) contents were determined in the sediments of the pond where the fish were treated. The ELISA method was used for OTC detection and the HPLC method was used for final quantification of OTC. The increasing contents of OTC in sediment depended on the repeated treatment and excretion of OTC by the fish. The concentration on Day 59 after the last administration was 1516 g·kg -1 OTC in the sediment, which indicates a long-term persistence of the substance in the environment.Antibiotics, HPLC, ELISA, medicated feeding stuff, fish

The assessment of mercury content in the muscle, liver and kidneys of fattening pigs and sows was conducted in the Czech Republic during the period of 2015–2019. The samples were collected from sows (n = 31) and fattening pigs (n = 210). The average mercury content in muscle, liver, and kidneys of sows over 5 years was 0.00057 ± 0.00004, 0.0045 ± 0.0008, and 0.0224 ± 0.0067 mg·kg-1, respectively. The average mercury content in muscle, liver, and kidneys of fattening pigs over the same period was 0.00059 ± 0.00004, 0.0012 ± 0.0001, and 0.0044 ± 0.0004 mg·kg-1, respectively. The maximum residual limit (MRL) for human consumption was exceeded in 14 kidney samples. The mercury content in liver did not differ significantly between sows and fattening pigs; in kidneys, the mercury content was higher in sows, with a significant difference in one year (P < 0.05). A slight decrease in the mercury content in kidneys and liver was observed in fattening pigs from the year 2015. In sows, there was a significant increase in the mercury content in kidneys in the year 2016. It can be concluded that there is a need for further monitoring of the mercury content in pig tissues in the Czech Republic.