Clinical and morphological investigations on the incidence of forms of rickets and their association with other pathological states in broiler chickens

The purpose of investigations was to determine, by means of pathomorphological methods, the incidence of different rickets forms and their role for the occurrence of other illnesses in broiler chickens in Bulgaria. Clinical, blood biochemical, gross anatomy and histological investigations were carried out in broiler chickens with signs of rickets. The studies were performed in 12 broiler flocks in 4 farms located in different regions of the country. Based on macro- and microscopic lesions, alterations specific for hypocalcaemic rickets were observed in two farms, whereas signs of hypophosphataemic rickets - in the other two. The rickets diagnosis was confirmed by analysis of blood serum calcium, magnesium and inorganic phosphate concentrations. At the age of 30-35 days, various pathological states were observed in the same farms. The presented results suggested that existing problems in studied flocks were associated with an earlier occurrence of rickets.     

Comparison of the pharmacokinetics of five aminoglycoside and aminocyclitol antibiotics using allometric analysis in mammal and bird species

The allometric equations relating the half-life, the volume of distribution and the total body clearance of gentamicin, amikacin, tobramycin, kanamycin and apramycin to body weight for mammalian and mammalian + avian species were defined. Literature data were used as a source of comparative pharmacokinetic data. For all antibiotics examined half-life intercepts ranged from 0.49 to 1.66, slopes from 0.05 to 0.45, volume of distribution intercepts--0.13-0.75, slope-- 0.77-1.41, total body clearance intercepts--0.88-8.8 and slope--0.62-1.04. A better relationship between pharmacokinetic parameters and body weight was shown when all values were included in the allometric analysis. Different values of intercept and slope between birds and mammals were found in gentamicin and apramycin studies. In some cases, slopes and intercepts changed when all values of pharmacokinetic parameters were included. We conclude that small difference exist between pharmacokinetics of gentamicin, amikacin, tobramycin, kanamycin and apramycin. The allometric equations shown in our study provide a basis to estimate dose intervals for mammals and birds for which specific information is lacking.     

Comparative pharmacokinetics of danofloxacin in common pheasants,guinea fowls and Japanese quails after intravenous and oral administration

1. The pharmacokinetics of danofloxacin was investigated in common pheasants, guinea fowls and Japanese quails after intravenous (i.v.) and oral (p.o.) administration at a dose of 10 mg kg^?1 body weight. Concentrations of the drug in serum were determined by high-performance liquid chromatography. The values of the pharmacokinetic parameters after both applications were calculated on the basis of a one-compartment model.

2. The elimination half-lives after i.v. injection were 6.82 ± 1.87, 3.31 ± 0.13 and 3.84 ± 0.89 h in pheasants, guinea fowls and quails, respectively. Total body clearance values were 0.45 ± 0.16, 1.23 ± 0.07 and 1.61 ± 0.34 l h^?1 kg^?1 in pheasants, guinea fowls and quails, respectively.

3. After p.o. administration, maximum serum concentrations were 0.54 ± 0.26, 0.51 ± 0.12 and 0.78 ± 0.11 μg ml^?1 respectively, reached at 2.04 ± 0.23, 10.4 ± 5.64 and 5.35 ± 0.47 h. Oral bioavailability values were 82.32% for pheasants, 79.46% for guinea fowls and 83.5% for Japanese quails. Pharmacokinetic/pharmacodynamic (PK/PD) predictive indices were also calculated and compared.     

Response of wheat and maize to different nitrogen sources: I. Plant growth and biomass accumulation

Maize (Zea mays L., hyhrid Pioneer 3737) and wheat (Triticum aestivum L., cultivar Jantar) were grown hydroponically in nutrient solutions containing 10 mM nitrogen (N) as either the nitrate (NO₃) anion or the ammonium (NH₄) cation or in a 1:1 combination of both. Maize and wheat plants had different responses to the N sources. Maize growth and biomass accumulation were greatest with the equal combination of NO₃ and NH₄, while NO₃ only was more favourable for wheat. The effects of the different N sources were detected on the 14th and 21st day for maize and wheat plants, respectively.     

The anti-nociceptive and cardiopulmonary effects of extradural fentanyl–xylazine in sheep

Objective To compare the anti‐nociceptive effects of extradural xylazine, fentanyl and a xylazine–fentanyl combination in sheep, and to measure the cardiopulmonary effects of the xylazine–fentanyl combination. Study design Prospective, randomized study. Animals Twenty‐five half‐merino ewes 2–4 years of age and body mass 54.2 ± 1.1 kg. Methods Six sheep in group 1 received 0.2 mg kg^?1 xylazine by extradural injection, six in group 2 received fentanyl 1.5 µg kg^?1 and 13 in group 3 received the combination of both treatments. In all groups, drugs were mixed with saline (0.15 mL kg^?1 before injection). Pulmonary and carotid arterial catheters were placed in seven sheep of group 3 which were used to evaluate cardiopulmonary effects. Anti‐nociception was determined by the response to electrical stimulation (40 V for 1.5 milliseconds) of the left flank and by superficial and deep muscular ‘pinpricking’ stimulation of the pelvic and thoracic limbs and thoracolumbar region. Results Lack of response to electrical stimulation at the left flank was present in 10 ± 1.1 minutes (mean ± SEM) (group 1) and in 4.5 ± 0.5 minutes in group 3. The duration of lack of response to electrical stimulation at the left flank was 96 ± 6 minutes in group 1 and 315 ± 6 minutes in group 3. Responses persisted in group 3. Significant decreases (p < 0.05) in cardiac output 30, 45, 60 and 90 minutes after injection, and in cardiac work at 30 and 45 minutes were observed in the seven animals of group 3. Arterial blood pH was lowest at 90 minutes, arterial bicarbonate was lowest at 60 minutes and values for both arterial and mixed venous base excess increased significantly at 60 and 90 minutes. There was no significant change from baseline values in heart rate, mean arterial blood pressure, respiratory rate, body temperature, systemic vascular resistance, arterial and mixed venous PO₂, PCO₂, oxygen saturation, blood oxygen content, haemoglobin concentration, mixed venous blood bicarbonate and pH. Conclusions Fentanyl decreases the onset time and prolongs the duration of anti‐nociception produced by xylazine. The combination decreases cardiac output but is without significant respiratory effects. Clinical relevance Further studies are required to show that surgery is possible in sheep after extradural xylazine–fentanyl injection.     

Pharmacokinetics of tobramycin in ducks and sex-related differences

The aims of the present study were to determine the disposition of tobramycin after single intravenous (IV) and intramuscular (IM) injections in ducks, and to establish any sex-related differences. Tobramycin sulfate was administered as a 2.5% water solution in a cross-over design at a dose of 5 mg/kg to 12 healthy ducks (six males and six females). Concentrations of the drug in serum were determined by a microbiological assay. The serum pharmacokinetic values for tobramycin were best represented using a one- or two-compartment open model, depending on the method of administration. Non-compartment analysis was also performed after IV administration. Tobramycin had a low degree of distribution and a relatively fast elimination. The mean volume of distribution in ducks (males and females) was higher than that reported in pigeons but lower than in chickens, with a slower rate of elimination. The IM injection resulted in a fast and complete absorption. The rate of elimination after IM administration was about twice as slow as in other avian species. Sex-related variations in tobramycin pharmacokinetics were similar to those reported for kanamycin and apramycin in hens and roosters.     

Changes in nitrate reductase activity,plastid pigment content,and plant mineral composition of wheat,rye, and triticale grown in the presence of aluminum

The effects of aluminum (Al) on nitrate reductase activity, plastid pigment content, and mineral element composition in wheat, rye, and triticale seedlings were studied. Different responses of the plant species to Al content in the growth solution were observed. Under conditions of different Al concentrations (from 1 to 10 ppm), nitrate reductase (NR) activity increased in wheat and triticale, while in rye an interference with nitrate reductase by Al was observed. A definite tendency in plastid pigment content changes independent on Al levels was not found. The chlorophyll “a”;, chlorophyll “b”;, and carotenoid contents were influenced in a different way in wheat, rye, and triticale seedlings. A positive effect of 1, 5, and 10 ppm Al on the nitrogen (N) content in the shoots of wheat and rye was observed. The N content in the shoots of triticale was not affected by the presence of Al. The presence of Al in the nutrient solution led to a tendency toward reduction of potassium (K), calcium (Ca), and magnesium (Mg) contents in the shoots of rye seedlings, a reduction of K in the shoots and manganese (Mn) content in roots of wheat, and a reduction of K in both shoots and roots and an accumulation of Mn in triticale roots. In general, our investigation on the effect of Al in the early stages of wheat, rye, and triticale development showed that a large number of biochemical and physiological parameters are required to characterize the plant responses to Al stress.     

Response of wheat and maize to different nitrogen sources: II. Nitrate reductase and glutamine synthetase enzyme activities,and plastid pigment content

Glutamine synthetase and nitrate reductase enzyme activities occurred both in roots and leaves of maize (Zea mays L., hybrid Pioneer 3737) and wheat (Triticum aestivum L., cultivar Jantar) plants grown on different nitrogen (N) sources. Enzyme activities and plastid pigment content in maize plants were higher in the treatments with a mixture of nitrate (NO₃) and ammonium (NH₄) than with either N source alone. In wheat plants, plastid pigment content, nitrate reductase activity, and root glutamine snynthetase activity were higher in the treatments where NO₃ alone was applied to the nutrient medium.