Circadian serum concentrations of tylosin in broilers after feed or water medication

1. Because tylosin is a time-dependent antibacterial agent, and because feeding and drinking of broilers decreases in late afternoon and ceases in the dark, it was hypothesised that serum concentrations of this drug are greatly reduced during the dark period. 2. The trial was carried out in a commercial poultry house, under standard broiler husbandry conditions, with food and water withdrawn from 22:00 until 07:00 h next morning and exposed to a natural light cycle of 13L:11D. 3. Broilers were given tylosin tartrate, in either feed or water, for 5 d as follows: 100, 200 and 300 ppm in feed, equivalent to 12.6, 25.2 and 37.8 mg/kg/d, respectively; and 200 and 400 mg/l in drinking water, equivalent to 51 to 102 mg/kg/d, respectively. 4. At 07:00 h on d 4, and for the next 40 h, hourly serum samples were obtained and analysed for tylosin by means of a microbiological assay. 5. Day vs night concentrations of tylosin expressed as area under the curve (AUC) in all groups revealed greater values during the day. The highest AUC and AUC(24)/minimal inhibitory concentration (MIC) ratio were obtained in the group medicated with 400 mg/l and the corresponding lowest values were found in the group medicated with 100 ppm in feed. 6. In conclusion, tylosin did not reach therapeutic serum concentrations during the dark period, at all dose rates tested when administered in feed or water. A sustained release form of this drug is needed to solve this inadequacy of tylosin medication in broilers.     

3-Acetyl-4'-isovaleryl tylosin for prevention of swine dysentery

The 21 field isolates of Treponema hyodysenteriae which were tested were sensitive to 3-acetyl-4'-isovaleryl tylosin (AIV); the minimal inhibitory concentration was 0.25 to 16 micrograms/ml. 3-Acetyl-4'-isovaleryl tylosin administered prophylactically to pigs at concentrations of 5 to 100 mg/kg of feed and tylosin at 110 mg/kg of feed for 28 or 31 days prevented swine dysentery induced by tylosin-sensitive T hyodysenteriae strain SQ2; 15 nonmedicated, inoculated control pigs had bloody diarrhea, and 9 pigs died. In 2 additional trials, AIV administered prophylactically for 28 days at 55 or 110 mg/kg of feed prevented swine dysentery induced by tylosin-insensitive T hyodysenteriae strain B204. All of the inoculated principal pigs medicated with AIV at 55 or 110 mg/kg of feed or carbadox at 55 mg/kg of feed and the noninoculated sentinel pigs for each group had solid feces throughout the 56-day trial. In the nonmedicated, inoculated control groups, bloody diarrhea began at 4 to 5 days after inoculation was done, and 9 of 10 principal pigs and 6 of 9 sentinel pigs had dysentery; 2 pigs died. In the groups medicated with AIV at 27.5 or 5.5 mg/kg of feed, all 5 principal pigs and 3 or 4 sentinel pigs in each group had dysentery; 3 or 4 pigs in each group died. In the group medicated with tylosin at 110 mg/kg of feed, 7 of 10 principal pigs and all 9 sentinel pigs had dysentery; 1 pig died.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of continuous in-feed medication with thiophanate on Ascaris suum and Oesophagostomum spp. egg output in young pigs

The full potential of anthelmintics now available for single dose treatment is not achieved because the devising system for worm control in piglets/weaners is not efficiently applicable in practice. Therefore an in-feed medication programme for growing young pigs, allowing only one feed lot to be handled by the farmer, was tested in two studies. Study A Feed containing 0.0225% thiophanate was continuously fed almost ad lib. to piglets from birth right up to about 25 kg body weight when ready for fattening. This control measure effectively prevented A. suum and Oesophagostomum from becoming established during the whole pre-fattening period, thus allowing "worm-free" weaners to be produced. -33% of animals receiving unmedicated feed harboured mature Oesophagostomum already at an age of 63 days when first examined. Three out of 97 unmedicated pigs were then A. suum egg-count positive. At the same time all medicated pigs, except one with a low Oesophagostomum egg output, were egg-count negative. All medicated were still egg-count negative at 23-29 days after the withdrawal of the feed. About 30% of unmedicated pigs were then shedding eggs of A. suum and Oesophagostomum respectively. At 45-49 days after the withdrawal of the medicated feed 8% of previously medicated pigs and 43% of unmedicated pigs were A. suum egg-count positive. The corresponding figures for Oesophagostomum egg-count positive pigs were 6% and 40% respectively. The acquisition of worm infections by previously medicated pigs most probably was made in the fattening unit after the withdrawal of the thiophanate medicated feed. Study B In this study it was further substantiated that in-feed medication of pigs with thiophanate prevents A. suum from becoming established. All treated pigs were A. suum egg-count negative at Day 43 and 46 after the withdrawal of the medicated feed whereas about 62% of untreated control pigs were shedding A. suum eggs at the same time. This finding justify the proposal that the in-feed medication performed prevented larval migration. Furthermore it was shown that the in-feed medication must proceed right up to the transfer of piglets to the fattening unit in order to achieve its full potential. Farrowing pens may be heavily contaminated with infective Oesophagostomum larvae at the end of the pre-fattening period resulting in sudden and heavy nodular worm infections after the withdrawal of the medicated feed.     

延胡索酸泰妙菌素对支原体和大肠杆菌混合感染的治疗试验

以人工诱发鸡毒支原体和大肠杆菌混合感染为模型,以酒石酸泰乐菌素为对照药物,评价了延胡索酸泰妙菌素的疗效.按每1 L水中分别加入312.5、468、625 mg延胡索酸泰妙菌素及500 mg酒石酸泰乐菌素的用量给病鸡饮水给药,连用5 d.试验表明,用药组的成活率、日增重、料肉比、气囊损伤度与感染对照组比较差异极显著(P＜0.01);延胡索酸泰妙菌素大剂量组日增重与小剂量组比较差异显著(P＜0.05),与其他各用药组比较差异极显著(P＜0.01),料肉比与其他各用药组比较差异极显著(P＜0.01);酒石酸泰乐菌素组的料肉比与延胡索酸泰妙菌素小剂量组比较差异不显著(P＞0.05);而与其他各组比较差异极显著(P＜0.01).数据分析表明,延胡索酸泰妙菌素大剂量组能有效地降低气囊损伤度,提高饲料转化率.     

Comparative pharmacokinetics and bioavailability of tylosin tartrate and tylosin phosphate after a single oral and i.v. administration in chickens

The pharmacokinetics and oral bioavailability of tylosin tartrate and tylosin phosphate were carried out in broiler chickens according to a principle of single dose, random, parallel design. The two formulations of tylosin were given orally and intravenously at a dose level of 10 mg/kg b.w to chicken after an overnight fasting (n = 10 chickens/group). Serial blood samples were collected at different time points up to 24 h postdrug administration. A high performance liquid chromatography method was used for the determination of tylosin concentrations in chicken plasma. The tylosin plasma concentration's time plot of each chicken was analyzed by the 3P97 software. The pharmacokinetics of tylosin was best described by a one‐compartmental open model 1st absorption after oral administration. After intravenous administration the pharmacokinetics of tylosin was best described by a two‐compartmental open model, and there were no significant differences between tylosin tartrate and tylosin phosphate. After oral administration, there were significant differences in the C_max (0.18 ± 0.01, 0.44 ± 0.09) and AUC (0.82 ± 0.05, 1.57 ± 0.25)between tylosin phosphate and tylosin tartrate. The calculated oral bioavailability (F) of tylosin tartrate and tylosin phosphate were 25.78% and 13.73%, respectively. Above all, we can reasonably conclude that, the absorption of tylosin tartrate is better than tylosin phosphate after oral administration.     

Interindividual variability in plasma concentrations after systemic exposure of swine to dietary doxycycline supplied with and without paracetamol: a population pharmacokinetic approach

Anorexigenic substances released during infection may hinder the therapeutic efficacy of in-feed antibiotics. Paracetamol (acetaminophen; PARA) inhibits the anorexia of infection and seems to improve the clinical efficacy of doxycycline (DOX) against bacterial respiratory disease in swine herds. In order to verify whether PARA selectively stimulates intake of DOX-medicated feed in diseased pigs, we documented the pharmacokinetics (PK) of DOX when coadministered with PARA and examined the effect of in-feed PARA on the interindividual variability in plasma concentrations after systemic exposure to in-feed DOX in swine herds with respiratory disease. Systemic exposure to DOX was measured with the area under the curve (AUC) of its plasma concentrations over time. First, a rich-sampling PK study of in-feed and i.v. DOX (10 mg/kg of BW) and PARA (30 and 10 mg/kg of BW, respectively) was performed on 5 pigs. The PK profiles of in-feed DOX were used in mathematical simulations to determine 5 optimal sampling times for the farm-based population PK study. A randomized, blind, parallel PK study was performed in 2 herds with bacterial respiratory disease, where liquid feed was fortified with DOX alone (5 mg x kg of BW(-1) x meal(-1)) or combined with PARA (15 mg x kg of BW(-1) x meal(-1)). Medicated meals were given twice, 12 h apart, to group-housed growing pigs (n > 50 pigs x treatment(-1) x herd(-1), totaling 215 pigs). Plasma concentrations of DOX and PARA were measured with HPLC. At variance with our expectations, PARA decreased (P = 0.069) mean AUC of in-feed DOX and did not decrease its variability (P > 0.34). Mean AUC of DOX increased with feed intake and with initial exposure to DOX, and was greater in sick animals. Therefore, symptomatic PARA-induced improvement in bacterial respiratory disease control with DOX is more likely caused by its analgesic/antipyretic effects than by its orexigenic effect. Interindividual variation in the AUC of DOX was large in pigs given group medication, even when sufficient feeding space was allowed and the amount of feed offered was greater than their requirements. Therefore, future studies to improve the efficacy of group antibiotic therapy should focus on feeding behavior characteristics as well as biopharmaceutical properties of medicated feeds.     

Haematological,biochemical and organ changes in broiler chickens fed varying levels of <Emphasis Type="Italic">Morinda lucida</Emphasis> (brimstone) leaf meal supplementation in the diets

The aim of this study was to evaluate the effects of dietary supplementation of Morinda lucida leaf meal (MLLM) on the haematology, biochemical and organ changes of broiler chickens. One hundred and ninety-eight day-old Marshall broiler chicks were completely randomised into 6 treatments in a 3?×?2 factorial arrangement of three levels of M. lucida leaf meal supplementation (0, 0.1 and 0.2 g/kg) with or without medication. The treatment consisted of both negative (without MLLM and routine medication) and positive (containing no MLLM but with routine medication) control groups while each treatment was replicated thrice. MLLM-supplemented diets and routine medication decreased (p?<?0.05) the white blood cell count compared to the negative control. Dietary supplementation with MLLM in combination with normal routine medication increased (p?<?0.05) total serum protein when compared with treatment group without MLLM and routine medication. Dietary supplementation with MLLM and routine medication reduced (p?<?0.05) serum creatinine concentration of the broiler chickens. Birds fed with 0.2 g/kg MLLM supplement coupled with medication and those on negative control had higher (p?<?0.05) creatinine values. Serum enzyme activities reduced (p?<?0.05) following supplementation. MLLM supplementation recorded no significant effect (p?>?0.05) on the liver, kidney, heart and gizzard. M. lucida leaf meal can be compared to routine medication for improved health status of broiler chickens. Dietary inclusion with 0.1 g/kg MLML combined with routine medication could be used in producing healthy and safe chickens.     

Prevention of pleuropneumonia in pigs by in-feed medication with sulphadimethoxine and sulphamethoxazole in combination with trimethoprim

The prophylactic effect of in-feed medication of conventional pigs with sulphadimethoxine (SDM), sulphamethoxazole (SMX), and trimethoprim (TMP) was tested by using an Actinobacillus pleuropneumoniae infection model. In each of five experiments, six pigs were given medicated feed twice daily and three pigs received antibiotic-free feed and served as positive (unmedicated, infected) controls. The following drugs or drug combinations were tested (in mg per kg feed): 500 SDM + 100 TMP, 500 SMX + 100 TMP, 125 SMX + 25 TMP, 125 SMX (alone) and 25 TMP (alone). After six days of feed medication, all animals were endobronchially inoculated with A. pleuropneumoniae in a dose of 1-3.10(4) colony-forming units (CFU). The response to the challenge in all control pigs was characterized by fever, lethargy, anorexia, reduced water consumption, and laboured breathing. At autopsy all controls manifested a fibrinous haemorrhagic pleuropneumonia. In-feed medication with 500 SDM + 100 TMP, 500 SMX + 100 TMP as well as 125 SMX + 25 TMP resulted in an effective protection against the challenge in all treated animals. After consumption of feed medicated with 125 mg per kg SMX or 25 mg per kg TMP, pleuropneumonia was evident in all challenged pigs. The results of this study indicate an in vivo potentiation of SMX and TMP in pigs against this respiratory tract pathogen.     

微生物处理对稻谷加工副产物营养品质的影响及其在肉鸡上的应用

文章旨在评估枯草芽孢杆菌发酵稻谷副产物对其营养品质的影响，并探讨该原料对肉鸡生长性能、组织器官相对重量及血清生化指标的影响。将初始体重为（46.09±0.12）g的600只商品肉仔鸡随机分为4组，每组5个重复，每个重复30只。稻谷副产物用1.5×108?CFU/kg枯草芽孢杆菌接种发酵48?h后，作为原料添加到肉鸡日粮中。对照组、T1～T3组肉鸡日粮分别添加0、60、120和180?g/kg微生物处理稻谷副产物。结果：稻谷副产物处理后粗蛋白质含量显著提高9.77%（P＜0.05），粗纤维含量显著降低29.77%（P＜0.05）。T3组肉鸡22～42?d及1～42?d平均日采食量分别较其他组显著降低19.01%、19.93%和28.78%（P＜0.05），12.65%、14.89%和20.46%（P＜0.05）。但T3组肉鸡22～42?d饲料报酬较其他组分别显著提高23.08%、24.67%和39.13%（P＜0.05），1～42?d饲料报酬较其他组分别显著提高12.86%、14.49%和25.40%（P＜0.05）。T3组肉鸡血清葡萄糖浓度较对照组和T1组分别显著提高11.67%和10.13%（P＜0.05），而T3组血清尿酸含量较其他组分别显著降低16.17%、12.64%和13.08%（P＜0.05）。结论：用1.5×108?CFU/kg枯草芽孢杆菌处理稻谷加工副产物可以提高其粗蛋白质含量，降低粗纤维水平。日粮中微生物处理稻谷副产物的添加水平达到18%时可以改善肉鸡饲料报酬。 [关键词]稻谷副产物|微生物处理|营养品质|肉鸡|生产     

Clinico-haematological and mineral studies on experimental maduramicin toxicity in chickens

Clinico-haematological and mineral studies were carried out in experimental chickens given maduramicin medicated feed at 5 and 10 ppm for 21 days. Maduramicin medication in both medicated groups caused growth retardation. Clinical signs namely watery diarrhoea, depression, dullness and ruffled feathers were noticed in chickens from second week of the medication at 10 ppm but this effect was seen from third week in the birds given maduramicin at 5 ppm. Maduramicin medication caused significant reduction in haemoglobin in both the medicated group from day 14 and total erythrocyte count and packed cell volume in 10 ppm group on day 21. There was an increase in MCV in 10 ppm group on day 21 indicating macrocytic anaemia and decrease in mean corpuscular haemoglobin concentration (MCHC) in both the medicated groups indicating hypochromic anaemia. The leucopenia due to lymphopenia was observed in 10 ppm group on day 21. Maduramicin medication caused significant increase in serum Zn in 10 ppm group and decrease in Cu concentration in both the medicated groups from day 14. It is concluded that maduramicin caused toxic effects from day 14 in both the medicated groups.     

Efficacy of in-feed medication with tylosin for the treatment and control of Mycoplasma hyopneumoniae infections

The efficacy of in-feed medication with tylosin for the treatment of enzootic pneumonia was examined in an experimental Mycoplasma hyopneumoniae infection model. One group of 10 conventional M. hyopneumoniae-free pigs was inoculated intratracheally with a highly virulent field isolate of M. hyopneumoniae; a second group of 10 pigs was inoculated in the same way and after 12 days was given tylosin at 100 mg/kg feed for 21 days; a third group of 10 pigs was inoculated with sterile culture medium, and these pigs were not given tylosin. The pigs were examined daily for clinical signs and each pig was given a respiratory disease score. Thirty-three days after they had been infected the pigs were euthanased, the lung lesions were quantified and samples of lung were processed for immunofluorescence testing for M. hyopneumoniae. The mean (sd) respiratory disease and lung lesion scores were significantly higher (P<0.05) in both the infected groups than in the uninfected group. Between 23 and 33 days after infection the mean respiratory disease score of the pigs treated with tylosin was 0.54 (0.22), significantly (P<0.05) lower than that of the infected pigs which were left untreated, 1.54 (0.46); similarly, their average lung lesion score, 1.72 (1.20), was significantly lower than that of the untreated pigs, 5.27 (3.85).     

黄连提取物对高饲养密度下肉鸡生长性能、血清生化指标及肠道微生物的影响

文章旨在研究高密度饲养条件下肉鸡日粮添加黄连提取物对其生长性能、血清生化指标及肠道微生物的影响。试验将640只平均体重为（42.12±0.16）g的肉鸡随机分为4组（T1～T4）,每组4个重复,每个重复40只。T1组肉鸡在高密度（20/m2）下饲喂基础日粮,T2组肉鸡在正常饲养密度（10只/m2）下饲喂基础日粮,T3组肉鸡在高饲养密度下饲喂基础日粮+20 mg/kg黄连提取物,T4组在正常饲养密度（10只/m2）饲喂基础日粮+20 mg/kg黄连提取物。在为期42 d的饲养试验结束后分析相关指标。结果：T4组22～42 d肉鸡平均日增重、22～42 d和1～42 d采食量最高（P＜0.05）,而T1组1～42 d肉鸡平均日增重和采食量最低（P＜0.05）。T1组肉鸡法氏囊重量分别较T2～T4组显著降低了18.53%、17.42%和18.89%（P＜0.05）。T4组肉鸡血清SOD和T-AOC活性最高（P＜0.05）,但血清丙二醛含量较T1组显著降低了29.04%（P＜0.05）。T1组肉鸡回肠大肠杆菌数量最高,分别较其他组显著提高了7.22%、6.93%和8.10%（P＜0.05）,但T1组肉鸡回肠乳酸杆菌数量较其他组显著降低了14.21%、15.74%和17.62%（P＜0.05）。T4组肉鸡回肠双歧杆菌数量较T1组显著提高了5.41%（P＜0.05）。结论：在高饲养密度条件下肉鸡日粮中添加20 mg/kg黄连提取物可以改善肉鸡生长性能和肠道有益菌数量,提高血清抗氧化指标,降低氧化应激。 [关键词]黄连提取物|饲养密度|肉鸡|生长性能|肠道微生物|血清生化     

Pharmacokinetics of tylosin in broiler chickens

Biological availability and pharmacokinetic properties of tylosin were determined in broiler chickens after oral (p.o.) and intravenous (i.v.) administration at a dose of 10 mg/kg. The calculated bioavailability--F%, by comparing AUC values--p.o. and AUC--i.v., ranged from 30%-34%. After intravenous injection tylosin was rapidly distributed in the organism, showing elimination half-life (t1/2 beta) values of 0.52 h and distribution volume (Vd) of 0.69 L/kg, at a clearance rate (Cl) of 5.30 +/- 0.59 ml/min/kg. After oral administration, tylosin has a similar distribution volume (Vd = 0.85 L/kg), while the elimination half-life t1/2 beta of 2.07 h was four times bigger than after i.v. administration at Cl = 4.40 +/- 0.27 ml/min/kg. The obtained value tmax = 1.5 h for tylosin after oral administration indicates that using this antibiotic with drinking water in broiler chickens is the method of choice. However, a relatively low value Cmax = 1.2 micrograms/ml after oral administration of tylosin shows that dosing of this antibiotic in broiler chickens should be higher than in other food producing animals.     

Prevention of swine dysentery with a combination of lincomycin and spectinomycin and resistance of swine dysentery to tylosin and sodium arsanilate.

The addition of a combination of lincomycin and spectinomycin to feed at the total concentrations of 44 and 77 mg/kg, beginning at the time of exposure and continuing for 8 weeks, prevented experimentally induced swine dysentery in swine. The disease did not develop after the medication was withdrawn. In contrast, swine dysentery, similar to that seen in the nonmedicated swine, did develop in simultaneously exposed swine treated with feed containing either 44 mg of tylosin or 99 mg sodium arsanilate/kg. The swine fed sodium arsanilate and which developed hemorrhagic diarrhea had a more severe form of this type of diarrhea than did the nonmedicated swine. After reexposure to inefective inoculum of swine dysentery 86 days after initial exposure, all remaining swine previously medicated with either tylosin or sodium arsanilate and all nonmedicated swine were immune; whereas 17 of the 24 swine fed the combination of lincomycin and spectinomycin were susceptible to swine dysentery and developed diarrhea.     

The Pharmacokinetics and Efficacy of Long-Term Low-Level and Split-Dose Administration of Albendazole Through In-Feed Formulations against Ovine and Caprine Parasitic Gastroenteritis

Two trials were conducted against natural and experimentally induced parasitic gastroenteritis in sheep and goats using an in-feed formulation of albendazole to evaluate its therapeutic and prophylactic efficacy. In the first trial, albendazole was incorporated in feed pellets to deliver an average daily dose of 0.7 mg/kg body weight in order to evaluate its prophylactic efficacy. In the second trial, feed pellets were offered to deliver an average total dose of 8.0 mg/kg body weight in two equal split doses in order to evaluate its curative efficacy.Sustained plasma concentrations of the active compound, albendazole sulphoxide, and its metabolite albendazole sulphone, sufficient to prevent establishment of infection, were achieved when the animals were allowed to feed on medicated pellets for 10 consecutive days. The bioavailability of the metabolites of albendazole following the administration of a therapeutic dose in two split doses of the in-feed formulation was sufficient to remove established adult nematodes. The concentrate feed pellets could be used for self-medicating small ruminants for therapeutic use as well as for prophylaxis based on their strategic use appropriate to the epidemiology of the parasitic disease.     

霉变饲料中添加复方霉菌毒素吸附剂对肉鸡人工感染发生的影响

本试验旨在研究霉变饲料和／或添加复方霉菌毒素吸附剂对肉鸡人工感染发生的影响。选取140羽1日龄健康的AA肉鸡随机分成7个组．每组4个重复。第1组为空白对照组,饲喂基础日粮;第2组饲喂霉变饲料;第3～7组以混合感染病鸡病变组织匀浆饮水制作人工感染疾病模型;第3～7组分别饲喂基础日粮、霉变饲料、霉变饲料＋复方霉菌毒素吸附剂、霉变饲料＋复方霉菌毒素吸附剂＋抗氧化剂、霉变饲料＋复方霉菌毒素吸附剂＋抗氧化剂＋中药增免剂。试验期35d。结果发现,肉鸡摄入霉变饲料与摄入正常饲料相比,提高肉鸡料重比和死淘率,显著降低肉鸡增重、胸腺指数、法氏囊指数,显著降低血清IBDV、H9N1v和NDV抗体水平（P〈0．05）。给人工感染肉鸡饲喂霉变饲料与饲喂正常饲料相比．显著提高料重比和死淘率,显著降低肉鸡增重、胸腺指数和脾脏指数,显著降低血清IFN-1、IL-2、IL-4和IL-12含量以及LTR,显著降低血清IBDV、H9N1V和NDV抗体水平（P〈0．05）。霉变饲料中添加复方霉菌毒素吸附剂能显著提高混合感染肉鸡增重,并降低料重比和死淘率（P〈0．05）,显著提高胸腺指数、法氏囊指数（P〈0．05）,显著提高血清IBDV、H9N1V和NDV抗体水平（P〈0．05）。可见,霉变饲料可导致肉鸡免疫功能抑制,加重肉鸡混合感染病情;复方霉菌毒素吸附剂能有效缓解霉变饲料对人工感染肉鸡生产性能、免疫功能和病情的不利影响,抗氧化剂和免疫功能增强剂可减轻霉变饲料的毒性作用。     

Preliminary clinical pharmacological investigations of tylosin and tiamulin in chickens

Summary The minimal inhibitory concentrations (M1C) of tiamulin and tylosin for mycoplasma. Gram-positive, and Gram-negative micro-organisms isolated from chickens were determinated by the agar dilution method. Median M1C values for tiamulin against Mycoplasma gallisepticum (0.05 μg/ml) and Mycoplasma synoviae (0.10 μg/ml) were 2 to 4 times lower than the corresponding values for tylosin. Tiamulin was also slightly more effective in vitro in inhibiting Escherichia coli, Pasteurella multocida, and beta-haemolytic streptococci than was tylosin. Groups of chicken were offered tiamulin medicated drinking water at rates of 125 and 250 mg/litre for 48 hours. Average serum tiamulin concentrations were 0.38 and 0.78 μg/ml, respectively. When tylosin tartrate was added to the drinking water at 500 and 700 mg/litre, average serum drug levels were 0.12 and 0.17 μg/ml, respectively. Tiamulin was 45% bound in chicken serum, as against 30% serum protein binding or tylosin. Correlations were made between free (non protein bound) serum drug levels and the MIC values of the two drugs. Such comparisons suggest that when tiamulin is given in the drinking water at rates of 125 to 250 mg/litre, better antimycoplasmal activity is to be expected in vivo than by giving tylosin tartrate in the drinking water at 500 to 700 mg/litre. Based on these data, no clinical efficacy of these dose rates can be expected in flocks infected by gram-negative microorganisms such as E. coli or P. multocida. The tylosin tartrate rate of 500 to 700 mg/litre, may be clinical ineffective the treatment of Staphylococcus aureus infections.     

The effect of various iodine supplementations and two different iodine sources on performance and iodine concentrations in different tissues of broilers

1. The objective of this study was to determine the influence of iodine (I) supplementation of feed, within the range of the European guidelines, on the performance of broiler chickens and I transfer into different organs and tissues, especially meat. The main emphasis was to assess whether broiler meat could be enriched and used as an I source in human nutrition. 2. Two experiments were performed, one with KI and the other with Ca(IO(3))(2). For each experiment, 288 d-old broiler chicks were divided into 4 groups (72 birds/group) and fed on diets with supplementations between 0 and 5 mg I/kg feed. The birds were reared to 35 d of age under standard conditions. Six birds per group were slaughtered at 35 d and samples of blood, thyroid gland, liver, pectoral and thigh meat taken. 3. Iodine treatment did not significantly affect the growth and slaughter performance of the broiler chickens. In all investigated parameters, I concentrations increased significantly with increasing I intake of the animals. The lowest I concentrations were measured in the meat, but they were considerably higher in blood serum, liver and thyroid gland. Since the I content of meat was still low in the highest supplemented group (highest median concentration: 67·8 μg I/kg thigh meat), there is no evidence that this could substantially improve I supply in human nutrition.     

Effects of feed intake and water hardness on fluralaner pharmacokinetics in layer chickens

BackgroundFluralaner is a novel drug belonging to the isoxazoline class that acts on external parasites of domestic animals. It is used systemically via drinking water, especially against red poultry mite in layer chickens. Fluralaner is frequently used in layers infected with D. gallinae. However, no study to date has investigated the effects of feed intake and water hardness.ObjectivesThis study aimed to investigate the effects of variable water hardness and feed intake on the pharmacokinetic profile of fluralaner.MethodsLayer chickens were divided into four groups (n = 8): fed + purified water (Group 1), feed restricted + purified water (Group 2), feed restricted + hard water (Group 3), and feed restricted + soft water (Group 4). After administering a single dose of the drug with drinking water, the blood samples were collected for 21 days. Fluralaner concentrations in plasma samples were determined by liquid chromatography/tandem mass spectrometry. The maximum plasma concentration (C_max), time to reach maximum plasma concentration (t_max), area under the concentration–time curve values (AUC_0-21d), half-life (t_1/2), and other pharmacokinetic parameters were calculated.ResultsAlthough the highest maximum plasma concentration (C_max) was determined in Group 1 (fed + purified water), no statistically significant difference was found in the C_max, t_max, t_1/2, MRT_{0-inf_obs}, Vz/F_obs, and Cl/F_{_obs} parameters between the experimental groups.ConclusionsIt was concluded that the feed intake or water hardness did not change the pharmacokinetic profile of fluralaner in layer chickens. Therefore, fluralaner could be used before or after feeding with the varying water hardness in poultry industry.     

The extraintestinal stages of Eimeria tenella and E. maxima in the chicken

Donor chickens given feed medicated with one or two levels of decoquinate or given non-medicated feed were infected with oocysts of Eimeria tenella or E. maxima per os. Twelve hours after inoculation with oocysts liver, mid-intestine or ceca homogenates were fed to previously uninfected recipient chickens. The results showed that continuous medication with decoquinate was effective in preventing the transfer of sporozoites from the intestine to the liver. Oocysts were detected in the feces of all recipients of tissue from non-medicated donors, showing that some sporozoites of E. maxima and E. tenella are normally transferred to liver. Young broiler chickens were immunized by oral inoculation of E. maxima oocysts. The immune status of similar chickens inoculated with sporozoites of the same species directly into the liver or spleen were assessed. During the experimental period half of the chicks were provided with non-medicated food and the remainder were given feed supplemented with decoquinate; decoquinate was effective in arresting the development of the sporozoites. Two weeks after initial infection the birds were challenged with oocysts of E. maxima per os. Injection of sporozoites into the spleen did not protect against challenge. Birds inoculated with sporozoites into the liver were unable to develop a significant level of immunity. When the drug pressure was removed from these birds, parasitism of the intestine occurred and immunity developed.