几种新型饲料添加剂及其应用

随着减少和限制促生长抗生素的呼声越来越高,尤其是中国加入WTO后所面临的新挑战,迫使人们寻求新的安全有效的抗生素替代物--生物源性饲料添加剂,它们包括酶制剂、微生态制剂、寡聚糖、低聚糖,大蒜素、甜菜碱,壳聚糖等,它们具有无污染,无残留,安全,有效等优点.     

寡聚糖在动物饲料中的应用

寡聚糖又名寡糖或低聚糖，通常是由2～10个单糖基通过糖苷键而连小聚合体，是一种介于单体单糖与高度聚合的多糖之间，并且具有类似于益生素作用的物质。由于其具有低热、稳定、安全无毒、无残留等良好的理化特性，以及具有调整肠道菌群平衡和提高免疫力等保健功能和促生长作用，因此寡聚糖在饲料中的应用逐渐引起了人们的极大兴趣。1对寡聚糖作为饲料添加剂的认识1.1产生背景　　自从1950年Stockstad报道在饲料中添加某种抗生素具有促生长效果以来，畜禽饲料添加抗生素日趋普遍，但随着人们对抗生素的负面效应，如药物残留、环境污染、耐…     

非抗生素类添加剂对仔猪保健作用的研究进展

寡聚糖、益生素、酸化剂、中草药、酶制剂等可改善仔猪的消化道内环境、提高仔猪抗病能力。本文综述了用它们替代抗生素预防仔猪疾病的研究进展，结果表明，这些添加剂可以防治卫猪腹泻等疾病，应用于仔猪生产。     

抗生素类饲料添加剂替代品研究进展

抗生素为人类的健康和畜牧业发展作出了巨大的贡献，但长期使用抗生素类饲料添加剂会产生细菌耐药性和畜产品中抗菌药物残留等负面效应，因此，抗生素类饲料添加剂替代品的研究就成为世界性命题，本文介绍了当前四种研究较深入的抗生素替代品；益生素、寡聚糖，中草药和糖萜素的作用机理及应用现状，并探讨了它们的发展趋势及方向。     

寡聚糖作为饲料添加剂的应用

抗生素的大量使用和滥用造成了动物抗病性降低,其在畜产品中的残留直接危害到人类的健康。寡聚糖作为一种安全、无毒、稳定的饲料添加剂,具有提高动物对营养物质吸收、促进动物生长、增强动物免疫力等作用,是较理想的抗生素替代品。寡聚糖替代抗生素应用于饲料工业和畜牧业将会有光明的前景。     

寡聚糖对三江白猪仔猪生长性能的影响

抗生素作为生长促进剂已在饲料中应用了半多个世纪，给养殖业带来了巨大的经济效益，然而它们的抗药性、二重感染及药物残留等问题，却一直是养殖业所关注的问题，因此积极寻找替代品，以取代其作为动物高效生长促进剂的地位。近年来，寡聚糖作为微生态调节剂在饲料中的应用给人们带来了希望。寡聚糖由于具有无污染、无残留而成为人们所期望的焦点。目前，这类产品在亚洲、     

寡聚糖在饲料工业上的运用

随着无公害养殖和绿色食品的发展，寡聚糖在饲料工业上的运用愈来愈广泛。寡聚糖又称寡糖 (oligosacchride)，是指 2～ 10个单糖通过糖苷键连接形成直链或支链的一类糖。它们不仅具有低热、稳定、安全无毒等良好的理化性质，而且具有调整肠道和提高免疫力等保健功能。国外早在 1960年就有报道指出，寡聚糖可作为免疫增强剂使用。日本首先将寡聚糖用于食品工业，日本市场上约有 90％的婴儿食品中含有寡聚糖，已知婴儿不能消化这些糖，添加的目的不是为了营养，而是为了保健作用。目前，国外已将寡聚糖用于饲料工业，这类寡聚糖加入饲料中…     

酵母细胞壁在家禽营养中的作用

目前市场上有许多酵母产品，它们包括：酵母培养物、活性干酵母、酵母提取物、Candida或Torula干酵母、辐射干酵母、甘露聚糖、酯化葡配甘露聚糖、多肽和核苷酸。许多这些产品含有Saccharomycescerevisia菌株，但它们的实际功能是完全不同的。当我们对Saccharomycescerevisiae进行进一步研究时，我们发现这个有意义的微生物可产生出许多不同的产品。从酵母发酵过程中而产生的一个最令人兴奋的产品之一是由Saccharomycescerevisiae酵母细胞壁提取的复杂碳水化合物———甘露聚糖（MOS）。由于使用抗生素和使用高水平的矿物元素作为生长促…     

新型饲料添加剂寡聚糖

寡聚糖又称低聚糖，一般具有耐高温、稳定、无毒等良好的理化性能，大部分不能被动物本身的消化酶所消化，但到达肠道后可作为有益微生物的底物，又不被病原微生物利用，从而促进有益微生物的繁殖，抑制有害微生物。由于抗生素的长期使用，产生了严重的弊端，使用越来越受到限制，寡聚糖作为一种可以替代的新型饲料添加剂被开发出来，并逐渐应用于饲料工业。１寡聚糖与活菌制剂的比较 近年来能有效抑制畜禽肠道中的有害菌，并使有益菌增生的天然活菌制剂──益生素，倍受人们青睐，具有提高机体抵抗力、促进动物生长、净化环境等作用。但其…     

中草药饲料添加剂对畜禽生长性能的影响

随着抗生素残留及细菌耐药性问题的突出,迫使畜禽饲养生产者不得不减少对抗生素和化学药品的依赖,继而去寻找替代抗生素的安全的饲料添加剂,如酶制剂、益生素、寡聚糖、酸化剂、活性肽等。中草药以其独有的效果,正在吸引着越来越多的饲料添加剂生产商的目光,其绿色性、天然性、多能性、安     

Penicillins and beta-lactamase inhibitor combinations.

beta-Lactamase production by bacteria continues to be one of the main mechanisms of bacterial resistance to beta-lactam antibiotics, and it seems likely to remain so. beta-Lactamase inhibitors provide 1 strategy to overcome this mechanism of bacterial resistance. Although 3 beta-lactamase inhibitor/antibiotic combinations are currently available, only 1 is approved for veterinary use. Because the beta-lactamase inhibitor must be present concurrently with the antibiotic for synergistic activity, it is important to consider the pharmacokinetic profile of these drugs in combination. These combinations were developed and optimized for human patients, so it is unlikely that they would achieve the ideal plasma and tissue concentrations and ratios in veterinary patients. Indeed, several differences in pharmacokinetic variables of beta-lactam antibiotic/beta-lactamase inhibitor agents have been described in dogs, compared with people. Such pharmacokinetic differences should be considered when interpreting in vitro susceptibility results in veterinary species, because these tests use ratios of drug that were established for humans. The beta-lactamase inhibitors represent a successful example of targeted drug development. However, the currently available inhibitors are active primarily against class-A beta-lactamases. Because the frequency with which class-C beta-lactamases are recognized is rapidly increasing in human isolates, and because beta-lactamase enzymes continue to evolve, new beta-lactamase inhibitors will need to be developed to target these enzymes.     

New drugs for horses and production animals in 2010

In 2010, three new active pharmaceutical ingredients were released on the German market for horses and food-producing animals. These were gamithromycin (Zactran?), a new macrolide antibiotic, Monepantel (Zolvix?), a broad spectrum anthelmintic with a novel mechanism, and Pergolide (Prascend?), the first dopamine receptor agonist for animals. Two substances have been approved for additional species. The tetracycline antibiotic doxycycline is now also authorized for turkeys and the nonsteroidal anti-inflammatory drug firocoxib from the group of cyclo-oxygenase-2 (COX-2) inhibitors is now available for horses. Furthermore, four new preparations with an interesting new pharmaceutical form, one drug with a new formulation and two drugs, which are interesting because of other criteria, were added to the market for horses and food producing animals.     

Dry cow therapy with a non-antibiotic intramammary teat seal - a review

: Dry cow antibiotic therapy is used to eliminate existing intramammary infections and to prevent new infections in the dry period. It is implemented as part of a total management system known as the 'Five-Point Plan' for mastitis control. Recent public concerns over the widespread prophylactic use of antibiotics, coupled with an increasing interest in organic farming, have lead to a re-evaluation of the treatment of cows at drying-off. As a result, attention has focussed on the use of novel alternatives to antibiotic therapy at the end of lactation. One such therapy involves the application of a non-antibiotic bismuth-based intramammary teat seal designed for use in cows with low cell counts at the end of lactation. Like the keratin plug that forms naturally in teats of cows that have been dried-off, teat seal forms a physical barrier to invading pathogens. To date, a number of independent studies have shown that teat seal is as effective as traditional dry cow antibiotic products in preventing the occurrence of new infection during the dry period in cows with somatic cell counts of ≤200,000 cells ml-1 at drying-off. This paper reviews the efficacy of teat seal in preventing dry period mastitis in both conventional and organic dairying systems.     

分子生物学技术在病毒性传染病中的临床应用

分子生物学方法目前是病毒检测和定性的一部分。PCR 技术可以检测传统病毒学方法检测不到的病毒,为病毒学进一步研究提供了技术平台。分子方法不仅能检测到抗生素抗性基因,而且还能进行病毒株基因分型,为公众提供健康信息。通过对抗病毒治疗应答的监控可检测到病毒抑制和病毒量,大大提高病毒的治疗水平。随着多重 PCR、实时定量荧光 PCR 出现和自动化效率的提高,分子检测方法价格将不断降低,分子方法发挥的作用将进步增加。这篇文章将重点叙述分子生物学方法在临床病毒学检测中的应用情况,通过一些例子阐明这些方法如何改变实验室诊断,达到防治病毒性传染病的目的。     

河南仔猪黄痢流行株部分微生物学特性及耐药性研究

从河南省不同地区数个中小型养猪场的仔猪黄痢自然发病病例中分离到7株细菌,经形态染色、培养特性及生化反应鉴定,均为大肠埃希氏杆菌(Escherichia Coli)。随后对7株细菌进行常规药敏试验,结果显示,7株分离株均对磷霉素、头孢曲松、头孢唑啉等药物高度敏感,而对庆大霉素、氟苯尼考、复方新诺明等药物均不敏感,说明河南省仔猪黄痢大肠杆菌的耐药性较为普遍。     

多糖类化合物的抗菌作用及其机制研究进展

多糖类化合物根据来源可分为植物多糖、动物多糖以及微生物多糖三大类。其不仅具有高效低毒、来源广泛的特点,还具有调节免疫功能、抗肿瘤、抗病毒、抗氧化、抗糖尿病、抗菌等多种生理功能。目前,人们已成功从高等植物、动物细胞膜以及微生物细胞壁中提取了大量多糖并广泛应用于食品、饲料、医药等行业中。随着细菌耐药性的不断产生,多糖类作为一种抗生素替代品已经成为国内外研究的热点。本文拟通过对多糖类化合物的抗菌活性以及主要机制进行详细阐述,为进一步深入开展多糖类化合物的生物活性及其作用机理研究,开发出更加安全、绿色高效的抗生素替代品提供理论依据。     

Susceptibility to vancomycin and other antibiotics of 165 Enterococcus strains isolated from dogs in Italy

The prevalence of antibiotic resistance, with special attention to vancomycin, in 165 Enterococcus strains isolated from dogs subjected or not to previous antibiotics treatment(s) was determined. For each strain, the minimum inhibitory concentration (MIC) to 9 antibiotics was assessed. All strains were sensible to vancomycin. High frequencies of resistance to erythromycin, tetracycline, rifampicin, and enrofloxacin were detected. E. faecium strains isolated from dogs subjected to antibiotic treatment were more resistant to tetracycline with respect to control dogs. Although enterococci from dog show a high degree of antibiotic resistance, they are sensitive to vancomycin. Therefore, the risk of transmission of vancomycin-resistant enterococcal strains from dogs to man is close to zero.     

The prophylactic effect of a dry-cow antibiotic against Streptococcus uberis

The prophylactic use of a dry-cow antibiotic for reducing the incidence of mastitis due to Streptococcus uberis was studied in four seasonally calving dairy herds involving 378 cows. The treatment was a long-acting dry-cow antibiotic preparation administered immediately after the last milking of lactation. New intramammary infections were identified by comparing the bacteriological status of quarters at drying off with that after calving, or through manual udder palpation during the dry period. The administration of dry-cow antibiotic to uninfected quarters at drying off reduced the overall incidence of new infections with Streptococcus uberis from 12.3% for untreated quarters to 1.2% of quarters (p<0.01). The reduction was significant (p<0.01) for both dry-period and post-calving infections. The susceptibility of uninfected quarters to new infection by Streptococcus uberis appeared to be unrelated to the infection status of a cow at drying off. Clinical infections during the dry period were most prevalent (97%) in quarters identified as having open teat canals. Fewer open teat canals (p<0.05) were observed among antibiotic treated quarters over the first 4 weeks of the dry period. Treated quarters had a lower (p<0.05) incidence of new clinical infection during the ensuing lactation and lower somatic cell counts. This did not affect production levels of milk, milk fat or protein. The results clearly indicated a prophylactic benefit for the dry cow antibiotic treatment against new Streptococcus uberis infections during the dry period.     

Asymptomatic intramammary infection with multidrug-resistant gram-negative bacteria in a research dairy farm: incidence and genetic basis of resistance

Nonpathogenic and opportunistic bacteria are increasingly recognized as reservoirs of antibiotic resistance genes. However, nothing is known about the mechanisms of antibiotic resistance in such bacteria isolated from the udders of healthy animals. In this study, 150 Gram-negative strains isolated from milk samples of healthy dairy cows were screened for the presence of a large pool of antibiotic resistance markers. Strains carrying β-lactamase-resistance genes, including SHV-1, SHV-11, SHV-27, TEM-1, OXY-1, CTX-M-2 and class 1 integrons, were detected. Our findings give the first evidence that nonpathogenic and opportunistic bacteria carrying antibiotic resistance genes can asymptomatically invade healthy udders and suggest that they may play a role in the dissemination of antibiotic resistance genes to the other udder pathogens.     

The prophylactic effect of a dry-cow antibiotic against Streptococcus uberis

The prophylactic use of a dry-cow antibiotic for reducing the incidence of mastitis due to Streptococcus uberis was studied in four seasonally calving dairy herds involving 378 cows. The treatment was a long-acting dry-cow antibiotic preparation administered immediately after the last milking of lactation. New intramammary infections were identified by comparing the bacteriological status of quarters at drying off with that after calving, or through manual udder palpation during the dry period. The administration of dry-cow antibiotic to uninfected quarters at drying off reduced the overall incidence of new infections with Streptococcus uberis from 12.3% for untreated quarters to 1.2% of quarters (p<0.01). The reduction was significant (p<0.01) for both dry-period and post-calving infections. The susceptibility of uninfected quarters to new infection by Streptococcus uberis appeared to be unrelated to the infection status of a cow at drying off. Clinical infections during the dry period were most prevalent (97%) in quarters identified as having open teat canals. Fewer open teat canals (p<0.05) were observed among antibiotic treated quarters over the first 4 weeks of the dry period. Treated quarters had a lower (p<0.05) incidence of new clinical infection during the ensuing lactation and lower somatic cell counts. This did not affect production levels of milk, milk fat or protein. The results clearly indicated a prophylactic benefit for the dry cow antibiotic treatment against new Streptococcus uberis infections during the dry period.