Pharmacokinetic analysis of cefquinome in healthy chickens

1. The pharmacokinetics of cefquinome (CEQ) in chickens was determined after intravenous (IV) and intramuscular (IM) administration of 2?mg/kg body weight. Plasma concentrations were measured by high performance liquid chromatography assay with an ultraviolet detector at 265?nm wavelength.

2. Plasma concentration–time data after IV administration were best fitted by a two-compartment model. The pharmacokinetic parameters following IV injection were distribution half-life 0·43?±?0·19?h, elimination half-life 1·29?±?0·10?h, total body clearance 0·35?±?0·04?l/kg/h, area under curve 5·33?±?0·55?µg/h/ml and volume of distribution at steady state 0·49?±?0·05?l/kg.

3. Plasma concentration–time data after IM administration were best described by a two-compartment model. The pharmacokinetic parameters after IM administration were absorption half-life 0·07?±?0·02?h, distribution half-life 0·58?±?0·27?h, elimination half-life 1·35?±?0·20?h, peak concentration 3·04?±?0·71?µg/ml and bioavailability 95·81?±?5·81%.

4. Cefquinome kinetics in chicken and data from other species were summarised and analysed to provide a comprehensive understanding of CEQ pharmacokinetics.     

Pharmacokinetics of gatifloxacin in broiler chickens following intravenous and oral administration

1. The pharmacokinetics of gatifloxacin were investigated following intravenous and oral administration of a single dose at a rate of 10?mg/kg body weight in broiler chicks.

2. Drug concentration in plasma was determined using High Performance Liquid Chromatography with ultraviolet detection on samples collected at frequent intervals after drug administration.

3. Following intravenous administration, the drug was rapidly distributed (t_1/2α: 0·33?±?0·008?h) and eliminated (t_1/2β: 3·62?±?0·03?h; Cl_B: 0·48?±?0·002?l/h/kg) from the body.

4. After oral administration, the drug was rapidly absorbed (C _max: 1·74?±?0·024?µg/mL; T _max: 2?h) and slowly eliminated (t_1/2β: 3·81?±?0·07?h) from the body. The apparent volume of distribution (V_d(area)), total body clearance (Cl_B) and mean residence time (MRT) were 3·61?±?0·04?l/kg, 0·66?±?0·01?l/h/kg and 7·16?±?0·08?h, respectively. The oral bioavailability of gatifloxacin was 72·96?±?1·10 %.

5. Oral administration of gatifloxacin at 10?mg/kg is likely to be highly efficacious against susceptible bacteria in broiler chickens.     

Pharmacokinetics and bioavailability of valnemulin in Muscovy ducks (Cairina moschata)

1. A pharmacokinetic study of valnemulin was conducted in healthy Muscovy ducks after intravenous (IV), intramuscular (IM) and oral administrations at a dose rate of 15?mg/kg body weight.

2. Drug concentrations in plasma were determined by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Pharmacokinetics parameters of valnemulin were analysed by compartmental analysis using the WinNonlin program.

3. After IV administration, valnemulin was widely distributed with a volume of distribution based on a terminal phase (V_z) of 8·19?±?3·07?l/kg, a mean elimination half-life (t_1/2Ke) of 2·63?h, and a clearance (Cl) value of 5·56?±?1·53?l/kg/h. Following intramuscular and oral administration, valnemulin was rapidly absorbed; the C_max was 0·44?±?0·13 and 0·12?±?0·02?µg/ml (achieved at 0·28 and 1·80?h), the t_1/2Ke was 3·17?±?3·83 and 4·83?±?1·81?h, and the absolute bioavailability (F) was 72% and 37%, respectively.

4. The plasma profile of valnemulin exhibited favourable pharmacokinetic characteristics in Muscovy ducks, such as wide distribution, and rapid absorption and elimination, though oral bioavailability was low.     

Head-cloaca controlled current stunning: assessment of brain and heart activity and meat quality

1. Behavioural and neural responses of 65 broilers to head-to-cloaca electrical stunning were evaluated and meat quality was assessed on two groups of 25 broilers stunned either head to cloaca, or in a conventional water bath method.

2. On the EEG recordings, a general epileptiform insult was observed when applying a current of 100?mA (100?Hz) or 70?mA (70?Hz) for 1·5?s. This general epileptiform insult shows a tonic, clonic and exhaustion phase followed by spikes of alpha, beta, theta and delta waves with duration of on average 34?±?12?s and 39?±?23?s respectively. These birds may have been unconscious for 20?s or longer, according to the correlation dimension analyses.

3. The heart rate decreased significantly (P? 4. Within a confidence limit of 95%, taking into account the number of animals with a reliable EEG, the chance of an effective stun of all broilers lies between 0·9 and 1·0?with a current of 70?mA (100?Hz for 1·5?s; n?=?28) and with 100?mA (100?Hz for 1·5?s; n?=?27).

5. The shear force of breast fillets was slightly lower (P? 6. It can be concluded that broilers are effectively stunned with the head-cloaca method by using a controlled current of 70?mA or 100?mA for 1·5?s. The fillets and legs of bird stunned head-cloaca showed fewer blood splashes in the muscles compared with birds stunned in a conventional water bath.     

Changes in body temperature during growth and in response to fasting in growing modern meat type chickens

1. Rectal or core body temperature was determined in a study to examine the effects of fasting in modern meat type broilers at three stages of growth, namely d 19, 33 and 47.

2. There were two treatment groups: fed with feed available ad libitum and fasted. Rectal temperatures were determined at noon (1200?h). At that time, feed was removed from the fasted group. The body temperatures were then determined again after 6, 12, 18 and 24?h.

3. Core body temperatures decreased with fasting. The decrease was evident after as little as 6?h of fasting with a further decline evident by 12?h.

4. Accompanying the decrease in body temperature with fasting there were decreases in the venous concentrations of carbon dioxide in the blood and sodium in the plasma.

5. The decrease in both body temperature and carbon dioxide presumably reflects depressed metabolic rate.

6. Unexpectedly, the core body temperature increased progressively with age in the control fed group (d 19?=?41·04?±?0·02°C, d 33?=?41·65?±?0·05°C, d 47?=?42·21?±?0·12°C).

7. In the fed control group, core body temperatures were reduced at night, when feeding activity would be anticipated to be greatly reduced.     

Distribution of chicken cathepsins B and L,cystatin and ovalbumin in extra-embryonic fluids during embryogenesis

1. Concentrations of chicken cathepsin B, cathepsin L, cystatin and ovalbumin were determined in the allantoic fluid, amniotic fluid and extracts of chorioallantoic membranes during days 6 to 12 of embryogenesis.

2. Similar trends for cystatin and ovalbumin were observed in the allantoic fluid with maximum concentrations of cystatin on day 7 (12?±?4?µg/ml) and ovalbumin on day 8 (～19?±?2·5?µg/ml) of embryonic development. The highest concentrations of cathepsin B was found on day 7 and of cathepsin L on day 10, but were significantly lower than those of cystatin and ovalbumin.

3. In the allantoic fluid, especially on day 7, considerable proportions of cystatin and ovalbumin were phosphorylated and contained phosphorylated serine.

4. Concentrations of cathepsin B and L, cystatin and ovalbumin in the amniotic fluid were variable but were comparable to those in allantoic fluid.     

The ostrich (Struthio camelus) ejaculate--effects of the method of collection, male age, month of the season, and daily frequency

1. Over three breeding seasons on a farm in Poland, semen was collected from 11 ostriches using the dummy and the teaser method to study the effects of the method of collection, male age, month in the breeding season, and daily collection frequency on ejaculate characteristics.

2. A total of 259 ejaculates were collected, with an average volume of 1·28?±?0·6 (±SEM) ml. Sperm concentration was 3·34?±?0·08?×?10⁹/ml, the total number of spermatozoa 4·32?±?0·22?×?10⁹, and motility 4·56?±?0·04.

3. There was no difference in ejaculates collected by the dummy and teaser methods, but the between-individual variation was considerable. Ejaculate characteristics increased with male age and varied between months, with little evidence for seasonal decline. Daily collections for 10 days did not affect sperm output.

4. The results open up avenues for further research on development of a viable protocol for artificial insemination in ostriches and efficient semen storage.

5. The between-male variation suggests that the ejaculate output could be maximized through selection.     

Pharmacokinetic–pharmacodynamic relationship of marbofloxacin for Escherichia coli and Pasturella multocida following repeated intramuscular administration in goats

The pharmacokinetics (PK) and pharmacodynamics (PD) of marbofloxacin (MBF) were determined in six healthy female goats of age 1.00–1.25 years after repeated administration of MBF. The MBF was administered intramuscularly (IM) at 2 mg kg^?1 day^?1 for 5 days. Plasma concentrations of MBF were determined by high‐performance liquid chromatography, and PK parameters were obtained using noncompartmental analysis. The MBF concentrations peaked at 1 hr, and peak concentration (C_max) was 1.760 µg/ml on day 1 and 1.817 µg/ml on day 5. Repeated dosing of MBF caused no significant change in PK parameters except area under curve (AUC) between day 1 (AUC_0–∞D1 = 7.67 ± 0.719 µg × hr/ml) and day 5 (AUC_0‐∞D5 = 8.70 ± 0.857 µg × hr/ml). A slight difference in mean residence time between 1st and 5th day of administration and accumulation index (AI = 1.13 ± 0.017) suggested lack of drug accumulation following repeated IM administration up to 5 days. Minimum inhibitory concentration (MIC) demonstrated that Escherichia coli (MIC = 0.04 µg/ml) and Pasturella multocida (MIC = 0.05 µg/ml) were highly sensitive to MBF. Time‐kill kinetics demonstrated rapid and concentration‐dependent activity of MBF against these pathogens. PK/PD integration of data for E. coli and P. multocida, using efficacy indices: C_max/MIC and AUC_0–24hr/MIC, suggested that IM administration of MBF at a dose of 2 mg kg^?1 day^?1 is appropriate to treat infections caused by E. coli. However, a dose of 5 mg kg^?1 day^?1 is recommended to treat pneumonia caused by P. multocida in goats. The study indicated that MBF can be used repeatedly at dosage of 2 mg/kg in goats without risk of drug accumulation up to 5 days.     

Pharmacokinetics of levofloxacin in Japanese quails (Coturnix japonica) following intravenous and oral administration

1. The pharmacokinetics of levofloxacin were investigated in Japanese quails after a single dose of 10?mg/kg BW, given either intravenously or orally.

2. Following intravenous administration, the mean value of distribution at steady state (Vd_ss), total body clearance (Cl_tot) and mean residence time (MRT) of levofloxacin were 1·25?l/kg, 0·39?l/h/kg and 2·72?h, respectively.

3. Following oral administration of levofloxacin, the peak plasma concentration (C_max) was 3·31?µg/ml and was achieved at a maximum time (T_max) of 2?h. Mean residence time (MRT), mean absorption time (MAT) and bioavailability were 4·26?h, 1·54?h and 69·01%, respectively. In vitro plasma protein binding of levofloxacin was 23·52%.

4. Based on pharmacokinetic and pharmacodynamic integration, an oral dose of 10?mg/kg levofloxacin for every 12?h is recommended for a successful clinical effect in quails.     

Interaction of transport distance and body weight on preslaughter stress and breast meat quality of broilers

1. The objective of the study was to investigate the effect of transport distance on blood metabolites and breast meat quality of broilers slaughtered at different weights.

2. The study was conducted on Ross 308 broilers from 27 different flocks reared under similar conditions. Slaughter weight was classified as <2·0?kg, 2·0–2·4?kg, and >2·4?kg. Transport distance was categorised as short (65?km), medium (115?km) and long (165?km) distance representing 90, 155 and 220?minutes at an average 45?km/h speed, for each slaughter weight.

3. Higher heterophils and heterophil:lymphocyte (H/L) ratios were obtained for broilers transported over a long distance. Long distance transport increased blood albumin, glucose, and triglycerides levels for <2·0?kg broilers, which did not differ from broilers slaughtered at >2·4?kg after long-distance transport.

4. Broilers slaughtered at >2·4?kg after long-distance transport had lower pH_u, and paler and tougher breast meat, than those broilers slaughtered at <2·0?kg after long-distance transport.

5. A negative correlation was obtained between pH_u and L*, thawing loss and texture. The L* value was negatively correlated with a*; and positively correlated with b*, thawing and cooking losses.

6. It was concluded that the effect of transport distance could not be evaluated independently of slaughter weight. The interaction between transport distance and slaughter weight contributes to preslaughter stress and meat quality.     

Pharmacokinetic studies of levofloxacin after oral administration in healthy and febrile cow calves

The present experiment was designed to study the pharmacokinetics of levofloxacin in six healthy cross bred female cow calves (4 to 6 months age) weighing between 40 to 80 kg. Plasma from blood was separated by centrifugation at 10,000 rpm. Quantitative estimation of levofloxacin was done by UV-VIS spectrophotometer at 286 nm. The mean maximum plasma concentration (Cp_max ) of levofloxacin in febrile calves (5.28?±?0.32 µg/ml) did not differ significantly as compared with healthy calves (4.50?±?0.22 µg/ml) after single dose (20 mg/kg) oral administration. The mean therapeutic plasma concentration ( Cp_ther ) of levofloxacin was maintained for longer period in febrile calves (10 h) as compared to healthy calves ( 8 h). The mean maximum urine concentration (Cu_max) in febrile (40.86?±?2.19 µg/ml) also did not differ significantly as compared with healthy calves (39.38?±?2.43 µg/ml). No significant difference in various pharmacokinetic parameters of plasma was observed in healthy calves ( β?=?0.23?±?0.01/h ; t1/2 β?=?3.00?±?0.17 h and MRT?=?4.66?±?0.14 h ) and febrile calves ( β?=?0.23?±?0.01/ h; t1/2 β?=?3.05?±?0.16 h and MRT?=?5.04?±?0.14 h ) . The mean value of β, and t ½ β calculated in urine also did not differ between healthy and febrile calves. However, the value of MRT(3.79?±?0.07 h) and Cl_B(1.65?±?0.09 ml/kg/min) calculated in urine of febrile calves significantly(p?B?=?2.09?±?0.13 ml/kg/min). Based on kinetic profile levofloxacin may be given orally at the dose rate of 1.49 mg/kg B.W.at 8 h intervals in febrile calves.     

Effects of hydrolysed Saccharomyces cerevisiae yeast and yeast cell wall components on live performance, intestinal histo-morphology and humoral immune response of broilers

1. The effects of enzymatically hydrolysed whole Saccharomyces cerevisiae yeast (HY) and the pellets of yeast cell wall (YCW) on production traits, the microbiology and histo-morphology of the small intestine, and humoral immune responses against Newcastle disease virus (NDV), of Ross 308 broilers were investigated.

2. The control group received a maize-soyabean meal based basal diet for 42 days. In the treated groups the basal diet was supplemented with 1?g/kg of HY and YCW. There were 8 replicate pens per group (n?=?12 birds/pen).

3. HY and YCW supplementation improved live weight (P?=?0·006) and FCR (P?=?0·003) at 42-d as compared with the control group.

4. In the small intestine, Salmonella spp and Escherichia coli numbers were higher (P?=?0·01) in the mucosa and lower (P?=?0·01) in the digesta of the HY and the YCW fed groups at 25?d of age. Lactobacillus in the duodenal and jejunal digesta was higher (P?

5. Following oral challenge with Salmonella pullorum, Escherichia coli and Lactobacillus increased (P?P?

6. Supplementation of HY and YCW increased villus height in the jejunum (P?=?0·02), width of villus in the ileum (P?=?0·034) and number of goblet cells in villi of the jejunum (P?=?0·006) and ileum (P?=?0·01).

7. YCW increased antibody level against NDV at 21 and 42?d of age compared with the control and the HY supplemented diets (P?

8. It was concluded that HY and YCW improved growth and feed efficiency in broilers, and considering the improvements in production traits and humoral immune responses, yeast cell wall may be a better dietary tool than the hydrolysed whole yeast cell as a performance enhancer for broilers.     

Effects of fermented plant product on growth performance, some blood variables, carcase characteristics, and intestinal histology in broilers

1. Fermented plant product (FPP) is a natural fermented food which is produced from a mixture of fermented fruit and vegetables, and rice bran (1:9).

2. To investigate the effects of FPP on growth performance, some blood variables, carcase characteristics and intestinal histology were determined in 192 broilers. They were divided into 4 groups, with 4 replicates of 12 chicks each; the chicks were provided ad libitum access to a diet consisting of 0, 0·5, 2·0 and 4·0% dietary FPP.

3. The crude protein and metabolisable energy concentrations of these diets were adjusted to 230?g CP/kg and 13·40?MJ ME/kg for the 7 to 21?d old chicks, and 200?g CP/kg and 13·40?MJ ME/kg for the 22 to 49?d old chicks, respectively.

4. At 49?d of age, feed intake, body weight gain and feed efficiency tended to increase with increase in FPP concentrations. Feed intake increased in the 4·0% dietary FPP group, BW gain increased in the 2·0% and 4·0% dietary FPP groups and feed efficiency increased in all experimental groups.

5. There were no differences among diets in the blood variables and carcase characteristics, except for total visceral organ weight, increased in all experimental groups.

6. Most of the intestinal villus heights, villus areas, epithelial cell areas and cell mitosis tended to increase with increase in FPP concentrations; duodenal villus height and cell mitosis in the 2·0 and 4·0% dietary FPP groups, and jejunal cell mitosis in all experimental groups were significantly increased. Compared with flat cells on the villus apical surface in the 0% FPP group, all experimental groups had protuberant cells in all intestinal parts.

7. In conclusion, hypertrophy of the villi and epithelial cells was observed in the present study, indicating improved growth performance, especially in the 4·0% dietary FPP group. Furthermore, increased total visceral organ weights suggested that FPP has no harmful effects on broilers.     

Divergent selection for shape of growth curve in Japanese quail. 6. Hatching time,hatchability and embryo mortality

1. Hatching time, hatchability of fertile eggs and embryo mortality under standard egg storage (1 or 5 days at 12?±?1°C and 55% relative humidity) and incubation conditions (37·5?±?0·2°C and 50% relative humidity) were analysed in lines long-term selected for high (HG) and low (LG) relative weight gain between 11 and 28?d of age, respectively, and constant body weight at 49?d of age.

2. Egg storage duration did not have an effect on average hatching time. LG quail, characterised by a fast postnatal growth rate immediately after hatching, hatched earlier than HG quail with a low early growth rate (about 391 vs. 406?h after egg setting, respectively).

3. In contrast to hatching time, the hatchability of fertile eggs was influenced by line as well as egg storage duration. Extended storage decreased hatching success in both lines. However, LG eggs exhibited a higher hatchability than HG eggs (1?d storage: 96·0 vs. 82·5%; 5?d storage: 88·7 vs. 72·7%, respectively).

4. Lower hatchability resulted mostly from a higher frequency of embryo death during early (up to d 7) and late (d 14 and later) phases of incubation.

5. An inadequate nutrient supply to embryos in consequence of developmental delay seems to be a key factor decreasing viability of embryos during incubation.     

Effect of dietary nucleotide supplementation on performance and development of the gastrointestinal tract of broilers

1. Two experiments were conducted to determine the effects of dietary nucleotide supplementation on broiler performance, and physical and morphological development of the gastrointestinal tract.

2. Experiment 1: A total of 180 one-d-old male chicks were placed in battery brooders in 3?×?6 replicate pens containing 10 chicks each. Chicks were randomly assigned to one of the three dietary treatments; a maize-soyabean meal based diet supplemented with 0, 0·25, and 0·50% Torula yeast RNA (as a source of nucleotides) from 0 to 16?d of age.

3. Experiment 2: A total of 1344 one-d-old male chicks were placed in floor pens and reared on recycled wood shavings (two flocks) under a high stocking density (0·068?m²/bird). Chicks were randomly assigned to one of the 4 dietary treatments (0, 0·25% Torula yeast RNA, 2% and 6% Nupro®) for the starter period (0 to 14?d of age) with 6 replicate pens containing 56 chicks each. All the birds were fed on the same common grower diet with no supplementation of nucleotides from 15 to 32?d of age.

4. Experiment 1: Supplementing the diets with up to 0·50% Torula yeast RNA did not affect broiler performance, or relative intestinal tract weight and length of broilers at any periods measured.

5. Experiment 2: From 0 to 14?d of age, broilers fed on the diets supplemented with 0·25% Torula yeast RNA and 2 and 6% Nupro® were significantly heavier and had improved feed conversion (feed:gain) ratios as compared with the birds fed on the control diet. Supplementing the starter diet only with 2% Nupro® supplementation significantly improved body weight (BW) gain as compared with the control diet over the entire experiment (0 to 32?d of age). Broilers fed on the diets supplemented with 2 and 6% Nupro® from 0 to 14?d of age had better feed conversion (feed:gain) ratios over the entire experiment (0 to 32?d of age) as compared with the birds fed on the control diet, even though the birds were only fed on the diets supplemented with Nupro® from 0 to 14?d of age. The broilers fed on the diets supplemented with 0·25% Torula yeast RNA and 2% Nupro® had higher villus height and an improved villus height-to-crypt depth ratio as compared with birds fed on the control or 6% Nupro® diet at 14?d of age.

6. It is generally assumed that nucleotides are not an essential nutrient; thus there is no need to supplement the diets of broilers reared under normal conditions. However, dietary nucleotide supplementation may be important to maintain maximum growth performance when birds are exposed to stress conditions, such as high stocking density combined with dirty litter.     

Comparative pharmacokinetics of orbifloxacin in healthy and Pasteurella multocida infected ducks

1. The pharmacokinetic aspects of orbifloxacin were studied in both healthy and naturally diseased ducks after a single intravenous and intramuscular dose of 5?mg?kg^?1 body weight. The serum concentrations of orbifloxacin following single intravenous and intramuscular injections were higher in diseased than in healthy ducks.

2. The disposition of orbifloxacin after a single intravenous injection was described by a two-compartment open model in both healthy and diseased ducks. Orbifloxacin was distributed and eliminated at a significantly slower rate in diseased than in healthy ducks. The total body clearance (Cl_B) was lower in diseased (0·131?l?kg^?1?h^?1) than healthy ducks (0·191?l?kg^?1?h^?1).

3. Following intramuscular administration of orbifloxacin, the peak serum concentration (C_max) was higher in diseased than in healthy ducks, and this was achieved at a maximum time (t_max) of 1·114 and 0·993?h, respectively. The drug was eliminated at a significant slower rate in diseased ducks (elimination half-life t _{0·5( el )?}=?5·07?h) than in healthy ducks (elimination half-life t _{0·5( el )?}=?4·18?h).

4. These results indicate that drug elimination patterns in healthy and diseased ducks are not the same. The pharmacokinetic profile of the drug is altered in diseased ducks due to the increased serum orbifloxacin concentrations compared with clinically healthy ducks. In conclusion, 5?mg?kg^?1 body weight of orbifloxacin administered as a single dose once daily could be useful in the treatment of disease caused by Pasteurella multocida pathogen in ducks.     

Characteristics of cold-induced dark,firm, dry broiler chicken breast meat

1. A study was designed to characterise dark, firm, dry (DFD) breast meat resulting from cold exposure of broilers and compare its properties with normal breast meat from cold-stressed and control birds.

2. A total of 140 broilers were selected from 5- and 6-week-old birds exposed to cold temperatures ranging from ?18 to ?4°C, or a control temperature of +20°C for 3?h in an environmental chamber. Half of these birds were slaughtered immediately following the cold exposure and the other half were given 2?h of lairage.

3. Breast meat samples were categorised based on ultimate pH (pH_u) and colour L* (lightness) values into normal (5·7?≤?pH_u?≤?6·1; 46?≤?L*?≤?53) breast meat from control (control-normal) or cold-stressed (cold-normal) birds, and DFD (pH_u?>?6·1; L*? 4. Residual glycogen was not different between cold-DFD and control-normal breast meat. Lactate concentration was lower in cold-DFD compared with control-normal breast meat. Lactate concentration almost tripled for all the samples by 30?h post-mortem, which resulted in a drop in pH of normal meat, but did not have any effect on pH of DFD breast meat. Glycolytic potential at both 5?min and 30?h post-mortem was lower in DFD breast meat compared with the normal breast meat from both cold-stressed and control birds.

5. Cold-DFD breast meat was significantly darker, with higher pH_u, lower cook loss, higher water-binding capacity and processing cook yield than cold-normal and control-normal breast meat, which were not different from each other.     

Effects of diet acidification and xylanase supplementation on performance, nutrient digestibility, duodenal histology and gut microflora of broilers fed wheat based diet

1. The objective of this experiment was to study the influences of xylanase and citric acid on the performance, nutrient digestibility, digesta viscosity, duodenal histology, and gut microflora of broilers fed on a wheat based diet.

2. The experiment was carried out as a 2?×?3 factorial arrangement with two concentrations of xylanase (0 and 200?mg/kg) and three concentrations of citric acid (0, 20 and 40?g/kg). A total of 408 one-day-old chickens with similar body weight were distributed into 24 pens with 17 birds/pen. Each dietary treatment was given to 4 replicate pens from 0 to 24?d of age. To determine the apparent nutrient digestibility, chromic oxide (3?g/kg) was added to the diets as an indigestible marker.

3. Xylanase significantly increased body weight gain at 24?d of age by 1·4% and improved gain-to-feed (G:F) by 3·6%. The inclusion of 40?g/kg citric acid decreased feed intake and body weight gain by 15·4% and 11·8%, respectively. The inclusion of 20?g/kg of citric acid decreased feed intake, but it did not affect body weight gain of broilers at 24?d of age. The inclusion of 20 and 40?g/kg citric acid improved G:F by 3·8 and 4·3% respectively. Xylanase significantly decreased the viscosity of digesta and improved retention of DM, CP, and energy.

4. Xylanase and citric acid did not have any effect on the histo-morphology of the duodenum and intestinal microbial population.

5. In conclusion, citric acid at 20?g/kg decreased feed intake, did not have a negative effect on body weight gain, and improved G:F. Xylanase decreased digesta viscosity, increased nutrient retention and consequently improved performance of broilers fed on a wheat based diet.     

Orally administered doxycycline accumulates in synovial fluid compared to plasma

Reasons for performing study: Tetracycline compounds have been used to slow the progression of osteoarthritis (OA) and rheumatoid arthritis but the concentration of doxycycline attained in synovial fluid following oral, low‐dose administration has yet to be determined. Objective: To determine the concentration of doxycycline in synovial fluid following oral, low‐dose administration. Methods: Six mature horses received doxycycline (5 mg/kg bwt q. 12 h for 5 doses). Venous blood and synovial fluid samples were collected at t = 0, 0.25, 0.5, 1, 12, 24, 48 and 72 h. Doxycycline concentrations were measured using reverse phase high pressure liquid chromatography with ultraviolet detection. Results: Doxycycline concentrations at all time points after t = 0 were above the lower limit of quantification for the assay. Plasma concentrations of doxycycline were above 0.21 µg/ml at t = 0.5 h. The mean ± s.d. peak concentration (C_max) of doxycycline in plasma was 0.37 ± 0.22 µg/ml and time to peak concentration was 0.54 ± 0.19 h. Synovial fluid concentrations of doxycycline were above 0.12 µg/ml 1 h after drug administration. The mean C_max of doxycycline in the synovial fluid was 0.27 ± 0.10 µg/ml. The penetration factor of doxycycline from plasma into synovial fluid, as determined by a ratio of the area‐under‐the‐curve for synovial fluid:plasma during the sampling period, was 4.6. Potential relevance: Orally administered doxycycline distributes easily into synovial fluid with a penetration factor of 4.6. Terminal half‐life of the drug in synovial fluid was longer than in the plasma, indicating possible accumulation in this compartment. Further in vivo studies are warranted to define a medication protocol prior to routine clinical use of doxycycline for the treatment of OA.     

Isolation, identification and antimicrobial susceptibility of Bacteroides fragilis group strains recovered from broiler faeces

1. The objective was to evaluate the occurrence of cultivable components of the Bacteroides fragilis group in faeces of broiler chickens and their antimicrobial susceptibility patterns.

2. Faecal samples of 36?×?45-d-old Cobb broilers of both sexes from 15 different flocks on one farm were diluted 10-fold and plated on to Bacteroides-bile-esculin agar for colony count and isolation. Identification was by molecular methods and antimicrobial susceptibility in the agar dilution assay.

3. A total of 236 isolates was recovered from a mean population of 3·32?×?10⁷ colony-forming units/g of faeces. B. fragilis was shown to be the predominant Bacteroides species (45·3%), followed by B. distasonis (35·6%), B. vulgatus (8·9%), B. ovatus (2·5%) and B. stercoris (1·3%).

4. Among 204 bacterial isolates tested, high resistance to ampicillin (98·5%), norfloxacin (95·1%) and tetracycline (88·2%) were observed. High (89·7%) multi-drug resistance was observed to 3–7 of the tested drugs.

5. Components of the B. fragilis group were sub-dominant in broiler faecal microbiota, with a different species pattern compared with human and high antimicrobial multi-drug resistance.