致雏鸡脑炎粪肠球菌分离鉴定与遗传进化分析

为鉴定致雏鸡脑炎的病原菌的生物学特征、致病性和耐药性,本研究从黑龙江哈尔滨某孵化场的发病雏鸡中分离得到一株病原菌,经过分离、形态学观察,生化鉴定以及16 S rDNA序列测定分析,并接种小鼠、雏鸡试验测定致病性,药敏纸片法测定对20种抗生素的敏感性。结果表明:该分离株为粪肠球菌,对小鼠、雏鸡均致病,并且该菌株的耐药性较强,对链霉素、头孢唑林钠等14种抗生素耐受。     

一株不发酵乳糖致病性大肠杆菌的分离与鉴定

从广东某珍珠鸡场发病死亡的初产珍珠鸡肝脏中分离到一株细菌,经培养特性与生化特性观察,以致病性试验和血清型鉴定,结合其16SrRNA序列分析,判定其为大肠杆菌。这是一株不发酵乳糖的致病性大肠杆菌。     

一株禽源致病性大肠杆菌的分离与鉴定

通过细菌分离培养、形态学观察、生化试验鉴定证实陕西某发病鸡场分离出一株致病性大肠杆菌，并利用致病性试验复制该病例，通过药敏实验确定敏感药物，临床实验确定此药物属于敏感性药物，治疗效果较好。     

猪禽致病性大肠杆菌的分离鉴定与药敏分析

为研究致病性大肠杆菌的耐药性,本文从广东省内临床发病猪禽的内脏中分离出50株菌株,经过分离鉴定试验筛选出23株致病性大肠杆菌,最后对23株致病性大肠杆菌进行药敏试验。药敏试验实验结果表明,所分离的23株致病性大肠杆菌对头孢吡肟、赛头孢、新头孢、林可霉素、恩诺沙星、环丙沙星、泰乐菌素、替米考星等抗菌药较为敏感,高度敏感和中度敏感比率之和均在75%以上。所有菌株至少对3种抗菌药耐药,27号菌和36号菌对抗菌药有较强耐药性,分别对12和11种药物耐药。对于猪源致病性大肠杆菌,可选环丙沙星、新头孢和恩诺沙星进行治疗。对禽源致病性大肠杆菌,可选新头孢、头孢吡肟和环丙沙星用于治疗。     

牛黄菌种的选育,驯化与鉴定

从生长牛黄的牛体胆囊中分离出二株细菌．经过细菌形态学，特殊培养基培养、生化试验及动物毒性试验检查判断为两株无致病性大肠杆菌。经过耐胆汁培养驯化，该菌株能在牛体内外胆汁中长期存活，并在胆囊中产生β－葡萄糖醛酸苷酶。经血清学鉴定为两株不同血清型大肠杆菌。     

一株A型副鸡嗜血杆菌的分离鉴定

从山东省某蛋鸡场发病鸡群中分离到一株细菌,经培养特性观察、生化试验、V因子生长试验、致病性试验和PCR试验,证实分离菌为一株致病性副鸡嗜血杆菌,血清型鉴定该菌为A型。药物敏感性试验表明分离菌对头孢噻肟、头孢曲松、丁胺卡那霉素高度敏感,对硫酸新霉素、强力霉素中度敏感,对磺胺间甲氧嘧啶钠、环丙沙星、庆大霉素耐药。     

鸵鸟新城疫病毒和大肠埃希菌感染的诊断

从某鸵鸟养殖场发病死亡的鸵鸟肝脏和脾脏用鸡胚分离到一株病毒,经血凝试验和血凝抑制试验鉴定为新城疫病毒,动物致病性试验表明该病毒对雏鸡有较强的致病性.同时分离到一种细菌,通过培养特性、菌体形态、菌落形态、染色特性及生化试验等一系列鉴定,确定为大肠埃希菌.药敏试验表明该株大肠埃希菌对头孢类抗生素高度敏感,而对红霉素、氨苄青霉素、四环素等抗生素表现为不同程度的耐药.     

副猪嗜血杆菌流行病学调查及两株分离株耐药性和致病性分析

为了解山东地区副猪嗜血杆菌病的流行情况和流行菌株的生物学特性及致病性,将2016-2018年山东省12个地区送检的103个发病猪的病料进行细菌分离,并对疑似菌株进行形态学观察、PCR鉴定及血清型鉴定,对两株流行菌株进行了培养特性观察、生化特性鉴定、药敏试验及致病性研究。最终分离获得29株副猪嗜血杆菌,分离率为28.16%,其中血清型4型和5型最为流行,其次是1型和12型。该病多发于春秋两季,31~50日龄的仔猪感染率最高。两株流行菌株LZ株和LC株均对青霉素类、头孢类等药物高度敏感,LZ株对庆大霉素、卡那霉素等中度敏感,对林可霉素、链霉素不敏感,LC株对庆大霉素、林可霉素等中度敏感,对卡那霉素、链霉素不敏感;生化特性试验结果显示,LC株和LZ株的硝酸盐还原试验、接触酶试验、葡萄糖发酵试验以及果糖发酵试验的结果均为阳性,吲哚试验、氧化酶试验、甘露醇发酵试验的结果均为阴性;动物致病性试验表明LZ株和LC株均具有较强的毒力,最小发病剂量分别为4.5×10^9 CFU和6.0×10^9 CFU。该研究为副猪嗜血杆菌病的防治提供了重要的参考依据。     

副猪嗜血杆菌的分离鉴定和药敏试验

采用细菌学检测方法和PCR技术对来自四川省遂宁市某规模化养猪场疑似副猪嗜血杆菌(HPS)感染的发病猪只肺脏等病料进行了HPS分离鉴定,结果分离出1株疑似HPS的细菌,经形态学、染色及培养特性检测、生化试验、血清型试验16 S rDNA序列分析,鉴定为4型HPS.动物致病性试验显示HPS分离株均具有较强致病性,药敏试验表...     

狐源屎肠球菌的分离鉴定及药敏试验

为研究病死狐的发病原因,从死亡狐狸肺脏中分离出1株细菌,命名为分离株11001。然后对分离菌株进行形态学鉴定、16S rRNA鉴定、特异PCR检测、药敏试验、毒力基因检测以及致病性试验。结果表明,分离株培养可见灰色干燥小菌落,革兰氏阳性球状菌,16S rRNA鉴定为屎肠球菌,PCR扩增条带为112 bp,与屎肠球菌片段大小一致;毒力基因检测显示该分离株携带屎肠球菌的致病基因,对氯霉素及万古霉素表现出一定的敏感性。致病性试验显示,接种分离株小鼠死亡。证实该株狐源分离株为屎肠球菌,且具有致病性,可能是引起狐狸死亡的主要原因。     

Dietary L‐arginine supplement alleviates hepatic heat stress and improves feed conversion ratio of Pekin ducks exposed to high environmental temperature

The current intensive indoor production system of commercial Pekin ducks never allows adequate water for swimming or wetting. Therefore, heat stress is a key factor affecting health and growth of ducks in the hot regions and season. Experiment 1 was conducted to study whether heat stress was deleterious to certain organs of ducks. Forty‐one‐day‐old mixed‐sex Pekin ducks were randomly allocated to four electrically heated battery brooders comprised of 10 ducks each. Ducks were suddenly exposed to 37 °C ambient temperature for 3 h and then slaughtered, in one brooder at 21 days and in another brooder at 49 days of age. The results showed that body weight and weight of immune organs, particularly liver markedly decreased in acute heat stress ducks compared with the control. Experiment 2 was carried out to investigate the influences of dietary L‐arginine (Arg) supplement on weight and compositions of certain lymphoid organs, and growth performance in Pekin ducks, under daily cyclic hot temperature environment. A total of 151‐day‐old mixed‐sex Pekin ducks were randomly divided into one negative control and two treatment groups, fed experimental diets supplemented with 0, 5, and 10 g L‐Arginine (L‐Arg)/kg to the basal diet respectively. Ducks were exposed to cyclic high temperature simulating natural summer season. The results showed that the addition of L‐Arg improves feed conversion ratio (FCR) during a period of 7‐week trial, as well as increases hepatic weight relative to body weight at 21 days, while decreases the hepatic water content at 49 days of age. This study indicated that the liver was more sensitive to acute heat stress, and the hepatic relative weight and chemical composition could be regulated by dietary L‐Arg supplementation in Pekin ducks being reared at high ambient temperature. These beneficial effects of Arg on liver might be a cause of improved FCR.     

Systematic analysis of feeding behaviors and their effects on feed efficiency in Pekin ducks

Background: Feeding behavior study is important for animal husbandry and production. However, few studies were conducted on the feeding behavior and their relationship with feeding efficiency in Pekin ducks. In order to investigate the feeding behavior and their relationship with feed efficiency and other economic traits in Pekin ducks, we selected 358 male Pekin ducks and recorded feeding information between 3 to 6 wk of age using automatic electronic feeders, and compared the feeding behavior under different residual feed intake(RFI) levels.Results: We observed that total feed time, daily feed intake and feed intake per meal had strong positive correlations with feed efficiency traits; moreover, strong correlation between feed intake per meal and body weight was found(R=0.32, 0.36). Daily feeding rate meal and meal duration had weak correlations with feed efficiency(R=0.14~0.15). The phenotypic correlation of between-meal pauses, with feed efficiency was not observed. When daily changes were analyzed, high RFI ducks had the highest feed consumption over all times, and obvious differences in daily visits were found among different RFI level animals during the middle period; these differences were magnified with age, but there was no difference in daily meal number. Moreover, our data indicate that high RFI birds mainly take their meals at the edge of the population enclosure, where they are more susceptible to environmental interference.Conclusions: Overal, this study suggests that the general feeding behaviors can be accurately measured using automatic electronic feeders and certain feeding behaviors in Pekin ducks are associated with improved feed efficiency.     

The effect of route of inoculation on the virulence of raptorial Pasteurella multocida isolates in Pekin ducks (Anas platyrhynchos)

The purpose of this study was to determine the virulence of raptorial Pasteurella multocida for ducks and the effect of various routes of inoculation on virulence. Four-week-old Pekin ducks (Anas platyrhynchos) were challenged with one of three raptorial isolates (RTHA-2, RTHA-4, or WESO-1) by one of five inoculation routes (intranasal, intraocular, intravenous, oral, and subcutaneous). Ducks were monitored daily for mortality until 2 wk postchallenge. Results indicated that the intravenous route caused the most mortality for all isolates and that significant variation existed in the virulence among the sources of P. multocida, with WESO-1 causing the least mortality of the isolates tested.     

Weaning pigs at an early age decreases cellular immunity

An experiment involving 118 pigs was conducted to evaluate the influence of weaning pigs at four different ages on in vivo and in vitro cell-mediated immunity. One-half of each litter was weaned at 2, 3, 4 or 5 wk of age; the other one-half remained with the sow as nonweaned controls. Phytohemagglutinin skin-test responses were determined on all pigs. Blastogenic responses of mitogen-stimulated lymphocyte cultures were determined before and after weaning. The intradermal response to phytohemagglutinin was reduced (P less than .001) in pigs weaned when 2 or 3 wk old and was suppressed (P less than .05) in those weaned when 4 wk old. In vivo cellular immunity was not altered by weaning in 5-wk-old pigs. The capability of lymphocytes to undergo blastogenesis in response to phytohemagglutinin was decreased in pigs weaned at 2 and 3 wk of age (P less than .001 and P less than .01, respectively). Pokeweed mitogen-stimulated blastogenesis was lower (P less than .01) in pigs weaned at 2 wk of age. Mitogen-stimulated lymphocyte blastogenesis was similar (P greater than .10) in control pigs and those weaned when 5 wk old. These data suggested that weaning pigs when younger than 5 wk old causes physiological changes detrimental to cellular immune reactivity. Those changes could alter disease susceptibility in young pigs.     

Mating behavior, boar-to-boar behavior during rearing and soundness of boars penned individually or in groups from 6 to 27 weeks of age

Individual and group-reared boars were compared in two experiments, for treatment effects on mating behavior, growth rate, feed consumption and feed/gain. Soundness also was evaluated in one experiment. Boar-to-boar behaviors were studied in group-penned boars. In Exp. 1, boars were either reared in a group of five or individually from 12 to 27 wk of age, or group-penned from 12 to 19 wk and individually from 1-9 wk. In Exp. 2, boars were either penned individually from 6 to 27 wk, group-penned (eight/pen) from 6 to 27 wk, grouped from 6 to 12 wk and then penned individually, or individually penned from 6 to 12 wk and then group-penned. Beginning at 29 wk of age, boars were tested every 2 wk for mating behavior in the presence of an estrous gilt. Four mating tests were conducted in Exp. 1 and five tests in Exp. 2. Individually penned boars grew faster from 6 to 12 wk old in Exp. 2, but no other treatment effects on growth rate were observed. Treatment had very little effect on mating test behaviors, but individual penning markedly reduced leg soundness. Sheath sniffing first appeared at 16 to 18 wk of age in group-penned boars and was followed closely by anal sniffing. Side nosing increased between 20 and 23 wk. Mounting activity from 12 to 27 wk old was correlated with mating test score in Exp. 1 (.76; P less than .01) and Exp. 2 (.55; P less than .05).     

复合酶制剂对北京填鸭胴体性状、体脂沉积和营养物质表观消化率的影响

本试验旨在研究饲粮复合酶制剂水平对北京填鸭胴体性状、体脂沉积和营养物质表观消化率的影响。选取35日龄健康、大小均匀的雄性北京鸭96只,随机分成4个组,每个组6个重复,每个重复4只鸭。对照组饲喂玉米-豆粕型基础饲粮,试验1组、试验2组和试验3组饲粮分别在基础饲粮中添加100、200和300 mg/kg的复合酶制剂,试验鸭在35和36日龄饲粮填饲量分别为260和300 g,之后5 d各组饲粮填饲量均为400 g/d。试验期为7 d。结果表明:1)饲粮复合酶制剂水平对北京填鸭屠体重、屠体率、全净膛重、全净膛率、腿肌重、腿肌率、龙骨长和胸宽均无显著影响(P0.05),而对北京填鸭增重、胸肌重、胸肌率、胸肌厚、肌胃重和肌胃率有显著影响(P0.05)。试验2组和试验3组北京填鸭胸肌重和肌胃重分别比对照组显著提高了7.88%和7.60%(P0.05)。2)饲粮复合酶制剂水平对北京填鸭皮脂重、皮脂率、腹脂重、腹脂率、肝脏重、肝重率和肝脂率均无显著影响(P0.05)。试验1组皮脂厚与对照组相比显著提高了16.2%(P0.05)。3)饲粮复合酶制剂水平对北京填鸭干物质和总能表观消化率无显著影响(P0.05),而对北京填鸭粗蛋白质表观消化率有显著影响(P0.05)。由此可见,饲粮中添加复合酶制剂对北京填鸭体脂沉积无显著影响,但能够提高饲粮中粗蛋白质表观消化率,并促进胸肌和肌胃的生长发育。     

不同品系北京鸭肉用性能及肌肉品质特性的研究

本文对Z型北京鸭3个品系的胴体性能及肌肉品质进行了比较。结果表明:北京鸭3个品系间活重、胸肌重和胸肌率存在极显著差异(P<0.01),表现为Z4系>杂交系>Z1系。而3个品系的腿肌率、腹脂重、腹脂率、皮脂厚和肌间脂肪宽无显著差异。剪切力以Z1系北京鸭为最高;失水率以北京鸭杂交系为最低;肌肉pH值以杂交系北京鸭最高。杂交系北京鸭天门冬氨酸、苏氨酸、丝氨酸、谷氨酸、丙氨酸、胱氨酸、蛋氨酸、异亮氨酸、亮氨酸、苯丙氨酸、赖氨酸、组氨酸、精氨酸、以及总氨基酸含量显著高于北京鸭Z1、Z4系(P<0.05),而且肌苷酸和各种氨基酸含量以及总氨基酸含量均为杂交系北京鸭最高。综合本试验可得出:北京鸭杂交系肉品质优于父系和母系,在品种选育过程中发挥出了杂交优势,且Z1系×Z4系这种杂交组合有利于北京鸭肉质的改良。     

Pharmacokinetics of cyclosporine in woodchucks and Pekin ducks

The purpose of this study was to evaluate the pharmacokinetics of cyclosporine (Cy) in woodchucks ( Marmota monax ) and Pekin ducks. These data are needed to design rational dosing regimens. Pharmacokinetic parameters were calculated from blood concentration-time data obtained following intravenous (i.v.) administration of 10 mg/kg body weight to woodchucks and Pekin ducks. Whole blood samples were collected in EDTA and assayed using a commercially available radioimmunoassay kit that employs a monoclonal antibody specific for Cy. The blood concentration-time profile best Dtted an open, two-compartmental model in Pekin ducks. Compartmental analysis of data in woodchucks did not adequately describe the data. When non-compartmental pharmacokinetic analysis of the data was performed, the resulting mean (± SD) pharmacokinetic parameters in woodchucks and Pekin ducks, respectively, were as follows: volume of distribution at steady-state, 2.9 (± 0.8) and 2.7 (± 0.2) L/kg; systemic clearance, 10.2 (± 2.8) and 28.6 (± 6.1) mL/kg/min; mean residence time, 4.8 (± 1.1) and 1.6 (± 0.3). These data suggest that Pekin ducks clear Cy at a faster rate than do woodchucks and that a greater dose of Cy should be administered to Pekin ducks in order to achieve adequate immunosuppression.     

1株无致病力的鸭疫里氏杆菌的分离及鉴定

从安徽和县无病鸭场的健康鸭咽部分离到1株革兰氏阴性短杆菌,定名为LY-58株。经分离培养、形态学检查、生理生化试验、血清学鉴定及PCR鉴定,分离菌株被鉴定为2型鸭疫里氏杆菌(Riemerella anatipestifer,RA)。毒力实验显示,2型RA参照菌株RAF2对10日龄北京鸭的LD50为5.57×107CFU,而分离菌株LY-58的LD50大于1.0×1010CFU,可确定为无致病性。     

多元回归方程估测北京鸭屠体性状的研究

试验测定了202只6周龄北京鸭公鸭的体重X1、体尺性状(体斜长X2、龙骨长X3、胸宽X4)和屠体性状(胸肉重Y1、腿肉重Y2、皮脂重Y3、腹脂重Y4、瘦肉重Y5和脂肪重Y6)共10项指标,在分析体重、体尺性状与屠体性状的相关关系的基础上,以体重、体尺性状为自变量,屠体性状为依变量,构建了估测北京鸭活体屠体性状的回归方程。结果表明:6周龄北京鸭胸肉重、腿肉重、皮脂重、瘦肉重、脂肪重分别与体重、体尺性状呈极显著正相关(P<0.01),腹脂重与体重呈极显著正相关(P<0.01),与体尺性状呈显著正相关(P<0.05);建立的6个最优多元回归方程,经F检验回归关系均达极显著水平(P<0.01),各回归系数也均达到极显著水平(P<0.01),表明各方程的自变量与依变量之间真实存在着多元回归关系,可为估测北京鸭活体胸肉重、腿肉重、皮脂重、腹脂重、瘦肉重和脂肪重提供理论依据,具有一定的参考使用价值。