Effects of various feed additive strategies on broilers given 10× live coccidiosis vaccine

Currently, there is a need to investigate feed additive application strategies, especially those used in conjunction with live coccidiosis vaccines (LCV). The objective of this study was to determine the effects of the inclusion strategies of several commercially available feed additives using broilers sprayed with 10× live coccidiosis vaccines (LCV) throughout a 49 d grow-out. All birds received 10× LCV on d of hatch, excluding treatment (Trt) 1, the unmedicated negative control (NC). The positive control (PC; Trt 2), was also unmedicated, but birds were sprayed with 10× LCV. Birds assigned Trts 3 to 8 also received LCV, and diets consisted of the following additives: Virginiamycin (VA) at 20 g/t throughout with Salinomycin (SAL) at 40 g/t from d 14 to 28 (Trt 3); VA at 20 g/t throughout d zero to 49 (Trt 4); a Bacillus subtilis probiotic (PRO) with Bacitracin Methylene Disalicyalte (BMD) at 50 g/t from d zero to 49 (Trt 5); an herb and essential oil blend (EB) from d zero to 49 (Trt 6); BMD at 50 g/t throughout with an increased dose (200 g/t) from d 14 to 28 (Trt 7); and BMD at 50 g/t throughout with SAL (40 g/t) from d 14 to 28 (Trt 8). In general, birds fed Trts 3 and 7 demonstrated increased BW and BW gain when compared to those fed Trt 2 (NC). Birds fed Trt 5 exhibited similar d 49 BW to that of birds fed Trt 3 and 7 — however, better than those fed Trt 2. Of these Trts, birds fed Trt 3 demonstrated at d 17 increased ileal digesta viscosity and reduced lesion scores caused by Eimeria acervulina, although overall scores were low. Gastrointestinal organ measurements and morphology at d 17 were not significantly affected by Trt. Overall, these data suggest that feed additive strategies utilized in Trts 3, 5, and 7 are a viable option with using LCV.     

Research Progress on Adaptive Survival Relationship Between Small Colony Variants and Bacteria

Small colony variants (SCVs) have been shown to be part of the regular growth cycle, which are highly dynamic or stable and can be selected during various harsh conditions. The features of SCVs include slow growth, colony morphology irregular and biochemical characteristics abnormal, making the separation and identification of SCVs into trouble. SCVs can cause chronic persistent infection, but not lead to strong immune response to host. Furthermore, SCVs are serious resistant to antibacterials normally. In this paper, we introduce the phenotype classification of SCVs, the relationship with the host's immune response and the effects of antibacterials on SCVs, which will provide theoretical support for further research of SCVs.     

貂感染伪中间葡萄球菌的诊断及药敏试验

2013年初,山东某水貂场成年水貂出现零星死亡,病貂以呼吸道症状为主要特征。采集病死水貂的肺部,进行细菌分离培养。分离菌经染色镜检,培养特性,生化试验及菌株的16S rDNA序列分析等进一步检测表明:致病菌为伪中间葡萄球菌。根据其病史和流行病学的调查以及分离菌的动物致病性试验可以确诊为该貂场水貂发病死亡是感染伪中间葡萄球菌所致。药敏试验结果显示:该分离菌对氯霉素、美洛西林等抗生素敏感,而对复方新诺明、万古霉素等产生耐药。     

杀球灵(Diclazuril)和麦杜拉霉素(Maduramycin)等四种聚醚类抗菌素对鸡巨形艾美尔球虫(E.maxima)药效的笼饲试验

对杀球灵和其它4种聚醚类抗菌素麦杜拉霉素,那拉菌素(Narasin),拉萨洛菌素(Lasalocid),莫能菌素(Monensin)的抗巨形艾美尔球虫效力进行了笼饲试验.重度感染情况下,和感染不给药对照组相比,5ppm麦杜拉霉素,80ppm那拉菌素,100ppm拉萨洛菌素和100ppm莫能菌素可防止鸡只死亡,改善增重,减轻肠道病变和减少卵囊数量.1ppm杀球灵组出现10%死亡,但是从增重和病变来看,鸡只仍然受到保护,粪便里也很少见到卵囊.对肠粘涂片的观察显示杀球灵明显抑制了巨形艾美尔球虫的有性生殖阶段,即配子生殖阶段的发育.从抗球虫指数来看,上述5种药对巨形艾美尔球虫的效力依次是拉萨洛菌素,麦杜拉霉素,杀球灵,那拉菌素和莫能菌素.     

阿普拉霉素在山羊体内的代谢动力学研究

对阿普拉霉素在黑山羊体内的代谢动力学进行了初步分析．一次静脉推注阿普拉霉素６０００ｕ／ｋｇ·ｗ，给药后４ｈ内按不同时间采血，用抗菌素管碟法测定血药浓度，３只黑山羊的试验结果表明，血药浓度时间曲线符合二室开放模型，不符合单室开放模型，其药物代谢动力学参数如下：消除速率常数（β）０．９８９±０．００２（ｈ－１）；初始浓度（Ｂ）１４．１３０±２．０５６（Ｕ／１００ｍＬ）；消除半衰期（Ｔ１／２β）０．６９６±０．００６（ｈ）；维持有效血药浓度时间ＴＣＰ４．０６±０．１４（ｈ）；表观分布容积（Ｖｄ）４２９．１３±６４．６３（１００ｍＬ／ｍｇ）；廓清率（ＣＬＢ）４２４．６７±６３．６６（１００ｍＬ／ｋｇ·ｈ）．     

抗生素对高粱愈伤组织诱导和生长的影响

用羧苄青霉素等抗生素进行抑菌试验,以羧苄青霉素和头孢霉素的抑菌效果较好.头孢霉素对高梁愈伤组织的毒性表现出比羧苄青霉素大.浓度低于500 mg/L羧苄青霉素对高梁愈伤组织的生长起促进作用;而分化率随着羧苄青霉素浓度的提高而下降.在农杆菌介导高梁遗传转化时,选用羧苄青霉素是合适的,浓度以250 mg/L为宜.高梁愈伤组织对潮霉素的反应比卡那霉素更敏感,高梁不同基因型愈伤组织对卡那霉素和潮霉素的反应在褐化(死亡)率上表现不同.在以潮霉素作为抗性筛选标记时,选择压以50～75 mg/L为宜.     

乳源耐甲氧西林葡萄球菌的耐药性、 产毒性与生物膜形成能力检测

从安徽省合肥地区奶牛隐性乳房炎生乳中分离鉴定24株耐甲氧西林金黄色葡萄球菌(MRSA)。采用E-test方法测定12种抗菌药物对乳源MRSA合肥分离株的最小抑菌浓度,微量板半定量法测定乳源MRSA合肥分离株形成生物膜的能力,PCR方法检测这些分离株携带耐药基因、毒力基因和生物膜形成相关基因的情况。结果显示受试MRSA分离株对苯唑西林、克林霉素、甲氧苄胺嘧啶、红霉素、利福平、头孢噻肟、庆大霉素、环丙沙星、四霉素、丁胺卡那、替考拉宁和万古霉素的耐药率依次为100%、75%、54.2%、50%、45.8%、45.8%、33.3%、29.2%、25%、20.8%、4.2%和0%,且83.3%分离株呈现多重耐药;受试MRSA分离株携带耐药基因mec A、blatem-1、aac(6’)/aph(2")、Erm B、tet M和qac A基因的检出率分别为100%、54.2%、70.8%、33.3%、41.7%和50%,而毒力基因Clf A、Fn BPA、SEA、PVL、TSST、Hla、Ca L和Nuc的携带率分别为33.3%、83.3%、79.2%、37.5%、58.3%、87.5%、100%和100%;受试MRSA分离株中生物膜形成能力强、中等、弱以及不能形成生物膜的细菌分别占37.5%(9/24)、12.5%(3/24)、25%(6/24)和25%(6/24),生物膜形成相关基因ica A、ica D、agr、Sig B和Sar A基因的检出率分别为50%、50%、50%、91.7%和83.3%。结果表明,乳源MRSA合肥分离株均为产毒性和多重耐药性MRSA,且75%分离株具有生物膜形成能力。     

中国饲料2021年第1期目次

木纤维素或木质纤维素是一种不可溶性膳食纤维添加剂,主要成分为纤维素、半纤维素和木质素。研究表明,木纤维素具有提高家禽生产性能、促进肠道蠕动、改善肠道微生物区系及提高抗病力和免疫力等功能,因此木纤维素在畜禽限抗养殖中有着广泛的应用前景。本文基于国内外研究成果,对木纤维素的特性及应用进行综述,以期为木纤维素在家禽养殖中的应用提供参考。     

降锌禁抗背景下断奶仔猪抗腹泻锌源的选择

长期以来药理剂量(2 250 mg Zn/kg以上)氧化锌被广泛应用于缓解、预防断奶仔猪腹泻和促进生长。但长期高剂量添加对仔猪生长造成不良影响,国家农业农村部公告2625号对可添加的最高锌水平进行下调,并对饲料抗生素逐步实行全面禁止,在此背景下亟须挖掘和开发高效替代产品。文章从氧化锌的作用机理出发,对不同产品类型氧化锌及碱式氯化锌优劣势进行介绍,重点对具有推广应用优势的碱式氯化锌作为抗腹泻锌源在断奶仔猪生产中的应用进行综述,为进一步在断奶仔猪生产中合理运用锌源提供参考依据。     

四环素类抗生素在环境中的风险评估研究进展

四环素类抗生素因成本低、价格低、抗菌谱广及抗菌活性好等特点被广泛用于养殖业,由于其在动物体内吸收较少,大部分以原形或代谢物的形式排出体外,随动物的粪便、尿液进入环境。多项研究表明,四环素类抗生素在环境中的暴露量大,吸附能力强、迁移能力弱,微生物、光照及温度都会影响其在环境中的稳定性,其在环境中的暴露对植物生长、水生生物及微生物群落结构数量和抗性基因均会产生负面影响。作者综述了四环素类抗生素在环境中的暴露现状、吸附及降解行为特性、效应研究及其在环境中的风险评估现状,旨在引起人们对环境中四环素类抗生素污染的重视,为环境中四环素类抗生素及抗性基因的去除提供参考,并对今后四环素类抗生素的环境风险评估提出展望。