Pharmacokinetics and relative bioavailability of tiamulin in broiler chicken as influenced by different routes of administration

The bioavailability and pharmacokinetic disposition of tiamulin in broiler chicken were investigated after administration through the crop, drinking water, and feed at 40 mg/kg body weight. Residues of tiamulin in tissues of broiler chicken were also assessed. Plasma and tissue concentrations of tiamulin were analyzed by reverse‐phase high‐performance liquid chromatography (HPLC) method. Plasma concentration–time data were described by the non‐compartmental model for all three routes, and pharmacokinetic parameters were calculated. There were no significant differences (p > 0.05) in pharmacokinetic parameters and mean plasma concentrations of tiamulin between three routes tested (crop, water, and feed), indicating equal efficacy. Tiamulin residues in edible tissues (muscles, skin, and fat) were lower than the advocated maximum residue limit (MRL of 0.1 µg/g and that of liver was 1 µg/g) on the 3rd day. No traces were found on the 5th day after drug administration. This indicated that the withdrawal period (less than 5 days) is very short, which makes it safer. This study shows that tiamulin can be used with equal efficacy through all routes of administration in broiler chicken (crop, water, and feed).     

Content and distribution of different phosphorus forms in broiler chickens

To understand the background value of phosphorus in chickens, the quantitative distribution of different phosphorus forms, including total phosphorus (TP), free phosphate (FP) and phospholipid (PL), in viscera, blood and bones of broiler chickens was investigated. Results showed that phosphorus contents exhibited significant differences in different parts of chickens. TP content of breast and thigh meat was over 5.0 g/kg, in which most of the phosphorus was in the form of water‐soluble phosphates. TP content in viscera was higher than that in meat, and spleen was observed to contain the highest amount of phosphorus (10.0 g/kg). In all tested organs, FP and PL contents in liver were the highest, ranging between 1207–1989 and 81–369 mg/kg respectively. TP content in chicken bone was in the range of 52 716–136 643 mg/kg, and FP content in the bone was relatively lower than that in chicken meat.     

Effects of astaxanthin‐rich dried cell powder from Paracoccus carotinifaciens on carotenoid composition and lipid peroxidation in skeletal muscle of broiler chickens under thermo‐neutral or realistic high temperature conditions

Thirty‐two 15‐day old broiler chicks (Chunky strain ROSS 308) were randomly divided into four treatments in a 2 × 2 factorial design. The main factors were diet (basal diet or basal diet supplemented with 0.15% astaxanthin‐rich dried cell powder (Panaferd‐P [astaxanthin 30 ppm]) and ambient temperature (thermo‐neutral [25 ± 1°C] or high [35 ± 1°C for 6 hr]). Dietary supplementation with Panaferd‐P did not affect growth performance, though high ambient temperature decreased feed intake and the weight of breast tender muscle, liver, and heart. High ambient temperature also decreased redness in both breast and leg muscles of chickens, while Panaferd‐P increased redness and yellowness of breast and leg muscles of chickens. Panaferd‐P increased Paracoccus carotinifaciens‐derived pigments (i.e., adonixanthin, astaxanthin, adonirubin, and cantaxanthin) as well as corn‐derived pigments such as zeaxanthin and lutein in breast and leg muscles. High ambient temperature increased the malondialdehyde (MDA) concentration in breast muscle, while Panaferd‐P decreased the MDA concentration in breast muscle under both temperature conditions. Our results suggest that dietary supplementation with Panaferd‐P increases muscle carotenoid content, the redness and yellowness of meat and decreases the muscle MDA concentration in broiler chickens kept under thermo‐neutral or high ambient temperature conditions.     

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.     

Carcass characteristics,chemical and fatty acid composition and oxidative stability of meat from broiler chickens fed black cumin (Nigella sativa) seeds

A study was conducted to investigate the dietary supplementation of black cumin seeds (BCS) on carcass characteristics, chemical and fatty acid (FA) composition and antioxidant properties of thigh and breast meat of broiler chickens at 42 days of age. Three hundred sixty 1‐day‐old broiler chickens were allocated to five dietary treatment groups (each group containing eight replicate pens with each pen containing nine broiler chickens): basal diet (control; CON), CON + 0.05 g/kg of bacitracin methylene disalicylate (AB), CON + 5 g/kg of BCS (low dose of BCS), CON + 10 g/kg of BCS (medium dose of BCS) and CON + 20 g/kg of BCS (high dose of BCS). Weight (g) of slaughtered birds (p = .03), hot carcass (p = .007), breast (p = .03), thigh (p < .001), wing (p = .06), neck (p = .01), liver (p = .09), abdominal fat (p = .01) and total edible parts (p = .01) increased or tended to increase due to BCS supplementation compared with the CON. The concentrations of dry matter, crude protein and ether extract in chicken thigh and breast meat increased (p = .038 to <.001) with increasing doses of BCS in diets. The ferric reducing antioxidant activity in blood and meat increased linearly with increasing doses of BCS in the diets. However, peroxide values in meat were not affected by BCS and AB on both days 1 and 7 of storage at 4°C. Supplementation of BCS increased the concentrations of C14:1, C18:3n‐6, C20:1, C20:2 FA and PUFA linearly (p < .05) and tended to increase (p = .098) the concentration of C18:2cis linearly. However, the concentrations of C16:0 and C16:1 FA decreased linearly with increasing doses of BCS in the diets. In conclusion, dietary supplementation of BCS at 20 g/kg diet may improve slaughter body weight, beneficial FA concentrations and antioxidant properties of broiler chicken meat.     

Pharmacokinetics of oral amantadine in greyhound dogs

This study reports the pharmacokinetics of amantadine in greyhound dogs after oral administration. Five healthy greyhound dogs were used. A single oral dose of 100 mg amantadine hydrochloride (mean dose 2.8 mg/kg as amantadine hydrochloride) was administered to nonfasted subjects. Blood samples were collected at predetermined time points from 0 to 24 h after administration, and plasma concentrations of amantadine were measured by liquid chromatography with triple quadrupole mass spectrometry. Noncompartmental pharmacokinetic analyses were performed. Amantadine was well tolerated in all dogs with no adverse effects observed. The mean (range) amantadine C_MAX was 275 ng/mL (225–351 ng/mL) at 2.6 h (1–4 h) with a terminal half‐life of 4.96 h (4.11–6.59 h). The results of this study can be used to design dosages to assess multidose pharmacokinetics and dosages designed to achieve targeted concentrations in order to assess the clinical effects of amantadine in a variety of conditions including chronic pain. Further studies should also assess the pharmacokinetics of amantadine in other dog breeds or using population pharmacokinetics studies including multiple dog breeds to assess potential breed‐specific differences in the pharmacokinetics of amantadine in dogs.     

Dioxin residues in the edible tissue of broiler chicken

The aim of this study was to determine the contamination of broiler chicken with polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) after feeding either uncontaminated feed or feed contaminated with 1, 2 or 4 ng/kg toxic equivalents (TEQ). The feed was mixed with pure substances of PCDD/Fs to get the intended contamination. Ten groups of seven 1-day-old chickens each were housed in special cages for broiler fattening. The fattening period lasted for 6 weeks. The contaminated feed was given for either 2, 4, or 6 weeks, one group received uncontaminated feed (control group). After slaughtering the edible parts of the chickens breast and leg including the skin were homogenized. Body weight gain and feed conversion (kg feed/kg body weight gain) were in the normal range (final weight 1.98+/-0.07 kg; feed conversion 1.74+/-0.03). One kilogram edible tissue contained an average of 21.2+/-4.1% of the total TEQ-intake in all groups. The PCDD/Fs residues in the edible tissues significantly correlated with the amount of PCDD/Fs-intake (r=0.99; Pearson correlation). There was no decrease in dioxin residues (% of total PCDD/Fs intake) after a 2 or 4 weeks withdrawal period. The results of this trial predict that a threshold value of 2 pg/g chicken fat can be met if the PCDD/Fs content in chicken feed is not higher than 0.4 ng/kg.     

Residue depletion of amoxicillin and its major metabolites in eggs

The depletion of amoxicillin (AMO) and its major metabolites, amoxicilloic acid (AMA) and amoxicillin‐diketopiperazine‐2′,5′‐dione (DIKETO) in the albumen, yolk and whole egg was studied after the oral dose of AMO (25 and 50 mg/kg body weight) to laying hens once per day for five consecutive days. Egg samples were prepared by a simple liquid–liquid extraction procedure with acetonitrile and saturated methylene chloride and analysed using liquid chromatography–tandem mass spectrometry. The results showed that AMO, AMA and DIKETO residues were mainly distributed in the yolk, where particularly high concentrations of AMO and DIKETO were found, whereas the albumen contained high concentrations of AMA. This distribution suggested that AMO and DIKETO were depleted slowly in yolk, whereas AMA was depleted slowly in albumen. The amount of AMO residue positively correlated with the dose, and the theoretical withdrawal times, which were calculated based on the residue level falling below a safe limit, were 5.21 and 7.67 days at AMO doses of 25 and 50 mg/kg, respectively. Moreover, the theoretical withdrawal times for all residues in the whole egg were 8.00 and 9.11 days at doses of 25 and 50 mg/kg, respectively. Our findings suggested that 9 days was an appropriate withdrawal time for the use of AMO in laying hens.     

Study on differentiation during embryonic development across selective and ancestral breeds

In order to explore the effect of strain on diverging post‐hatch muscle properties, muscle regulation during embryo development was investigated in selected and unselected breeds. Four broiler strains were used: JingNing (JN) chicken (a Chinese native chicken), HuangYu (HY) broiler, BaiYu (BY) broiler and Hyline layer (commercial crossbred chickens). Results showed that the four breeds had almost the same characteristic during different incubation periods. BY broilers moved more than JN and Hyline layers from Hamburger & Hamilton stage (HH)24 to HH31 (P < 0.05). HY broilers moved more than JN and Hyline layers from HH27 to HH31 (P < 0.01). All the embryos were heavier daily from HH24 to ED18 (P < 0.05); broilers presented greater body weights than JN and hyline layers (P > 0.05); broilers presented smaller fiber diameter than JN chickens before HH31 (P > 0.05). From then on, JN chicken exhibited smaller fiber diameter compared to the broilers (P > 0.05). Western blotting indicated all the breeds had continuous insulin‐like growth factor‐I (IGF‐I) expression, with the highest expression level in broilers from HH19 to HH24 and highest expression level in JN chicks from HH27 to HH31. The results indicated that the diverging growth among breeds was already shown in embryonic stages; the different expression patterns of IGF‐I may be involved in cell proliferation and differentiation.     

Effects of thermo‐resistant non‐starch polysaccharide degrading multi‐enzyme on growth performance,meat quality,relative weights of body organs and blood profile in broiler chickens

This research was conducted to study the performance and carcass parameters of broiler chickens fed diets supplemented with heat‐treated non‐starch polysaccharide degrading enzyme. A total of 432 one‐day old Ross 308 broiler chickens were allocated to five treatments: (i) CON (basal diet), (ii) E1: CON + 0.05% multi‐enzyme, (iii) E2: CON + 0.1% multi‐enzyme, (iv) E3: CON + 0.05% thermo‐resistant multi‐enzyme and (v) E4: CON + 0.1% thermo‐resistant multi‐enzyme, each treatment consisted of six replications and 12 chickens in each replication. The chickens were housed in three floor battery cages during 28‐day experimental period. On days 1–7, gain in body weight (BWG) improved by feeding the diets supplemented with thermo‐resistant multi‐enzyme. On days 7–21 and 1–28, chickens fed the diets containing thermo‐resistant multi‐enzyme showed improved (p < 0.05) BWG and feed conversion ratio (FCR) compared to CON group. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme affected the percentage of drip loss on d 1 (p < 0.05). Drip loss percentage on days 3 and 5 and also meat colour were not affected significantly. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme did not affect the relative weights of organs but compared to CON group, relative weight of breast muscle increased and abdominal fat decreased (p < 0.05). Among measured blood constituents, chickens fed supplemented diets with thermo‐resistant multi‐enzyme showed higher (p < 0.05) IgG. Counts of red and white blood cells and lymphocyte percentage were not affected. In conclusion, the results demonstrated that supplementing pelleted diets with thermo‐resistant multi‐enzyme improved performance of broiler chickens.     

安徽省禽白血病感染的血清学调查及gp85基因的扩增

随机抽取安徽省3个肉种鸡场种鸡及3个地市农贸市场商品鸡的血清样本和泄殖腔拭子,采用ELISA进行鸡白血病检测,并对J亚群鸡白血病病毒抗体阳性鸡群中病鸡的肝组织、全血及上毒细胞提取DNA进行PCR扩增和基因测序。检测结果表明,3个肉种鸡场中J亚群鸡白血病抗体阳性检出率分别为：0、73.50%和15.22%;3个农贸市场商品鸡抗体阳性检出率分别为：12.00%、2.22%和9.10%。3个肉种鸡场A、B亚群鸡白血病的抗体阳性率分别为0、17.93%和1.08%,ALV抗原阳性率分别为2.17%、17.93%和15.22%。PCR检测结果表明,从可疑发病鸡的肝组织和全血中均能扩增出ALV-J gp85特异性片段。结果证实安徽省鸡群中有ALV-J感染,并呈不同程度的流行,应引起高度重视。     

Use of high‐density SNP data to identify patterns of diversity and signatures of selection in broiler chickens

The development of broiler chickens over the last 70 years has been accompanied by large phenotypic changes, so that the resulting genomic signatures of selection should be detectable by current statistical techniques with sufficiently dense genetic markers. Using two approaches, this study analysed high‐density SNP data from a broiler chicken line to detect low‐diversity genomic regions characteristic of past selection. Seven regions with zero diversity were identified across the genome. Most of these were very small and did not contain many genes. In addition, fifteen regions were identified with diversity increasing asymptotically from a low level. These regions were larger and thus generally included more genes. Several candidate genes for broiler traits were found within these ‘regression regions’, including IGF1, GPD2 and MTNR1AI. The results suggest that the identification of zero‐diversity regions is too restrictive for characterizing regions under selection, but that regions showing patterns of diversity along the chromosome that are consistent with selective sweeps contain a number of genes that are functional candidates for involvement in broiler development. Many regions identified in this study overlap or are close to regions identified in layer chicken populations, possibly due to their shared precommercialization history or to shared selection pressures between broilers and layers.     

Effects of Testosterone Propionate Residues on Broiler Tissue and Its Effect on Body Health

The study was conducted to investigate the effects of testosterone propionate supplementation on tissues residue of broilers,and its residual effect on serum biochemical parameters,testicular growth and development of broiler chickens,to provide a basis for the protection of animal products safety. A total of 160 male 60-day-old broilers with (2.2±0.1)kg body weight were selected and assigned to control group and testosterone propionate supplementation group. The chicken in control group were fed basal diets while that in testosterone propionate supplementation group were fed diets supplemented with 20 mg/kg testosterone propionate for 7 d. The broilers was slaughtered at the day of 2,6,11 and 17 d after the testosterone propionate supplemented diets were ending. The crest,liver,testis and musle were collected to measure the testosterone propionate residues and testosterone concentration by lquid chromatograph mass spectrometer mass spectrometer (HPLC-MS/MS). The serum samples were collected from the veins to measure the serum biochemical profiles by automatic biochemical analyzer. Testis samples were collected to measure the testis cell morphology and mastocyte accounts by HE and toluidine blue staining. The results showed that:①The testosterone propionate concentration in serum was the highest,followed by the crest. However,there was no testosterone propionate residues in breast muscle,leg muscle,liver and testis. The testosterone propionate concentration in crest was not affected by the withdrawal time (P>0.05). The content of testosterone propionate at 17 d of the withdrawal time was extremely significantly lower than that of 2,6 and 11 d (P<0.01),and there was a regressive between the residues of testosterone propionate in the blood and crest and withdrawal time.②Compared with the control group,the concentration of propionate in testis at the withdrawal time of 2,6,11 and 17 d was reduced 71.45%,63.46%,62.86% and 73.61% (P<0.01),respectively.③The relative weight of testis was significantly lower at the withdrawal time of 2 d (P<0.05). But there was no significant difference in liver relative weights among the two groups in all the withdrawal time (P>0.05).④Most of serum biochemical parameters (TP,ALB,A/G,CHO,TG,LDH,ALT and AST) were not significantly affected by testosterone propionate supplementation (P>0.05).⑤Testis lose the profiles, outed of the order of spermatogenic cells in tubes by testosterone propionate supplementation. Degranulation mass cell accounts,mast cells were higher than control group. In conclusion,the testosterone propionate could result in atrophy of the rooster testis,which could be detected by blood and crest samples,and the results could provide a basis for the study of livestock products safety.     

丙酸睾酮在肉鸡组织中残留及其对机体健康的影响

本研究旨在探讨丙酸睾酮在肉鸡组织中的残留及其对肉鸡血清生化指标及睾丸生长发育的影响,为保障畜产品安全提供检测依据。选取初始体重为（2.2±0.1） kg的60日龄青脚麻公鸡160只,随机分为对照组与试验组,每组4个重复,每个重复20只。对照组饲喂基础日粮,试验组饲喂添加20 mg/kg丙酸睾酮的试验日粮,连续饲喂7 d,分别于休药期第2、6、11、17天每组选择8只鸡屠宰,采集鸡冠、肝脏、睾丸和肌肉等组织,用液相色谱-质谱联用仪（HPLC-MS/MS）检测丙酸睾酮残留量、睾酮含量;翅静脉采集血液样品,分离血清后用全自动生化分析仪测定血清生化指标的含量;采集睾丸样品,利用HE染色病理组织检查、甲苯胺蓝病理形态学镜检观测睾丸组织细胞形态、肥大细胞数等。结果显示,①血液中丙酸睾酮残留量最高,鸡冠中残留量次之,胸肌、腿肌、肝脏和睾丸中无残留;休药期长短对鸡冠中丙酸睾酮残留量无显著影响（P>0.05）,休药17 d后血清丙酸睾酮含量极显著低于2、6和11 d （P<0.01）,且休药期与鸡冠、血液中的丙酸睾酮残留量呈一元二次回归关系。②试验组睾丸中睾酮含量在休药2、6、11、17 d时较对照组分别降低了71.45%、63.46%、62.86%、73.61%（P<0.01）。③在休药2 d时,试验组睾丸相对重量显著低于对照组（P<0.05）;试验组肝脏相对重量与对照组无显著差异（P>0.05）。④肉鸡血清大部分指标（总蛋白（TP）、白蛋白（ALB）、白球比（A/G）、胆固醇（CHO）、甘油三酯（TG）及乳酸脱氢酶（LDH）、谷丙转氨酶（ALT）和谷草转氨酶（AST）酶）均无显著变化（P>0.05）。⑤丙酸睾酮对公鸡睾丸的影响较大,细胞失去了原有的椭圆形,生精细胞在管腔中排列紊乱。试验组脱颗粒数目、肥大细胞（MC）数分别比对照组多。综上所述,饲喂丙酸睾酮会导致公鸡睾丸萎缩,可通过血液和鸡冠取样检测到其残留量,这一结果可为保障畜产品安全提供检测依据。     

Age‐related change of hepatic uridine diphosphate glucuronosyltransferase and sulfotransferase activities in male chickens and pigs

The hepatic activities of uridine diphosphate glucuronosyltransferase (UGT) and sulfotransferase (SULT) of male Ross 708 broiler chickens at the age of 1, 7, 14, 28, and 56 days and male Camborough‐29 pigs at the age of 1 day and 2, 5, 10, and 20 weeks were investigated. Glucuronidation and sulfation of 4‐nitrophenol were used to evaluate the activities. Porcine hepatic UGT and SULT activities were low at birth, peaked at around 5–10 weeks, and then declined. Both hepatic UGT and SULT activities of chickens were high at hatch and declined. Chicken hepatic UGT activity had a peak at the age of 28 days. Affinity of hepatic SULT to 4‐nitrophenol is similar in chickens and pigs, but the affinity of hepatic UGT in pigs was about 10 times higher than that in chickens. 4‐nitrophenol was predominantly conjugated by SULT instead of UGT in chicken livers from hatch to day 56. Conversely, hepatic UGT contributed predominantly in 4‐nitrophenol conjugation than the SULT in pigs from birth to 20 weeks. Therefore, age has significant impact on hepatic activities of UGT and SULT, and the importance of UGT and SULT on conjugation is different in chickens and pigs.     

Preparation and evaluation of chicken embryo-adapted fowl adenovirus serotype 4 vaccine in broiler chickens

The current study was planned to develop an efficient vaccine against hydropericardium syndrome virus (HSV). Currently, formalin-inactivated liver organ vaccines failed to protect the Pakistan broiler industry from this destructive disease of economic importance. A field isolate of the pathogenic hydropericardium syndrome virus was adapted to chicken embryos after four blind passages. The chicken embryo-adapted virus was further serially passaged (12 times) to get complete attenuation. Groups of broiler chickens free from maternal antibodies against HSV at the age of 14 days were immunized either with 16th passage attenuated HSV vaccine or commercially formalized liver organ vaccine. The antibody response, measured by enzyme-linked immunosorbent assay was significantly higher (P < 0.05) in the group immunized with the 16th passage attenuated HSV vaccine compared to the group immunized with liver organ vaccine at 7, 14, and 21 days post-immunization. At 24 days of age, the broiler chickens in each group were challenged with 10^3.83 embryo infectious dose₅₀ of pathogenic HSV and were observed for 7 days post-challenge. Vaccination with the 16th passage attenuated HSV gave 94.73% protection as validated on the basis of clinical signs (5.26%), gross lesions in the liver and heart (5.26%), histopathological lesions in the liver (1.5 ± 0.20), and mortality (5.26%). The birds inoculated with liver organ vaccine showed significantly low (p < 0.05; 55%) protection estimated on the basis of clinical signs (40%), gross lesions in the liver and heart (45%), histopathological lesions in the liver (2.7 ± 0.72), and mortality (35%). Birds in the unvaccinated control group showed high morbidity (84%), mortality (70%), gross (85%), and histopathological lesions (3.79 ± 0.14) with only 10% protection. In conclusion, this newly developed HSV vaccine proved to be immunogenic and has potential for controlling HSV infections in chickens.     

Influence of stewing time on the texture,ultrastructure and in vitro digestibility of meat from the yellow‐feathered chicken breed

This study assessed the influence of stewing (1, 2 or 3 h) on the texture, ultrastructure and in vitro digestibility of meat from the yellow‐feathered chicken, which is a popular broiler chicken in Asia. Results indicated that longer stewing considerably increased cooking loss of the chicken carcass and tenderness of thigh meat. After 3 h of stewing, protein digestibility decreased from 90.5% to 80.3% and fiber diameter decreased by 8.63 μm. The shear force value of breast meat decreased from 32.34 N at 1 h to 10.29 N at 2 h, and then increased to 39.98 N at 3 h. The texture profile of breast meat remarkably decreased during stewing. Moreover, increased stewing time induced longitudinal and transversal shrinkage of muscle fibers and the degradation of the myosin heavy chain. These findings suggested that prolonged stewing (3 h) resulted in decreased meat qualities, based on the changes in cooking loss, digestibility and texture profile, but that stewing for 2 h increased thigh and breast tenderness. Producers could utilize this information to stew yellow‐feathered chicken meat with desirable qualities.     

Withdrawal time of four pharmaceutical formulations of enrofloxacin in poultry according to different maximum residues limits

San Martin, B., Cornejo, J., Lapierre, L., Iragüen, D., Pérez, F., Hidalgo, H., Andre, F. Withdrawal time of four pharmaceutical formulations of enrofloxacin in poultry according to different maximum residues limits. J. vet. Pharmacol. Therap. 33 , 246–251. To ensure delivery of safe animal products to consumers, the withdrawal time (WDT) of drugs must be respected. Property differences among pharmaceutical formulations, for the same drugs, can lead to differences in the WDTs estimation. The WDTs of four commercial formulations of enrofloxacin (ENRO) in broiler chickens, considering MRLs established by different countries, were studied. Two hundred‐thirty‐four broiler chicks were allotted among four groups; the formulations were orally administered daily with 10 mg/kg bw. After treatment, six chickens of each group and two controls were slaughtered daily until day 9 post‐treatment. Samples of muscle and liver were collected, and analyzed using HPLC‐MS‐MS. The WDTs among formulations of ENRO showed differences of 24 and 48 h. Based on the European Community and Chile MRLs of 100 μg/kg (muscle) and 200 μg/kg (liver), the WDTs did not exceed 5 days. When Japan MRL was considered (10 μg/kg_,), the WDTs increased up to 8 days. These results indicate that for WDTs determination, the differences among pharmaceutical formulations of a drug must be considered as well as the MRLs.     

Up-regulation of Endothelin-1 and Endothelin type A receptor genes expression in the heart of broiler chickens versus layer chickens

To compare Endothelin (ET) production and genes expression of ET-1 and ET_A receptor (ET_AR) between broiler and layer chickens during rearing, semi-quantitative RT-PCR and enzyme immunometric assay were performed in the heart ventricles and serum. There were gradual elevations of ET-1 and ET_AR mRNAs in the left ventricle of broiler and layer chicken groups that were mainly significant (P < 0.05) at 28, 35 and 42 days of age with compared to previous days whereas were not significant between two groups.These gradual elevations of ET-1 and ET_AR mRNAs were also observed in the right ventricle that were significant (P < 0.05) at 28, 35 and 42 days of age in broilers and 42 days of age in layers with compared to previous days. Increasing of these mRNAs in the right ventricle of broiler chickens were significantly (P < 0.05) more than layer chickens at 28, 35 and 42 days. Serum ET in broilers was significantly (P < 0.05) higher than layer chickens at 28 and 42 days of age. It is concluded that circulating ET and cardiac ET-1, ET_AR genes expression is higher in broiler chickens than in layer chickens particularly after 21 days of age. It is probably that these breed differences make broiler chickens to be more susceptible to Endothelin related-cardiomyopathies such as congestive heart failure and ascites.     

Estimating danofloxacin withdrawal time in broiler chickens based on physiologically based pharmacokinetics modeling

In this study, a physiologically based pharmacokinetics (PBPK) model was firstly developed for danofloxacin in healthy broiler chickens after a single oral administration at 5 mg/kg bw. Then, the model extrapolation from healthy chickens to those infected with Pasteurella multocidaones was performed. The healthy model was validated through a comparison of predicted and previously published concentrations, which indicated that the healthy PBPK model had good predictive ability in plasma, lung, muscle, liver, and kidney, especially at the later sampling time points. Multiple dosing of administration was incorporated into the healthy and infected models. In addition, a Monte Carlo simulation (MCS) included 1000 iterations was further incorporated into both models to predict the withdrawal times of danofloxacin in healthy and infected chickens, which were estimated to be 3 and 2 days, respectively.