Stakeholder position paper: poultry

There has been renewed concern in recent years about the use of antibiotics in food animal production and the potential risk it may pose to public health due to transfer of antibiotic resistance factors via the food supply. Although a legitimate concern, it bears reminding that this debate is not new. It has been ongoing for decades, yet there is still no documented case of human treatment failure due to antibiotic resistant bacteria acquired from USDA-inspected meat and poultry. This fact strongly suggests that the issue is not the imminent threat as has been portrayed by certain individuals or advocacy groups. The poultry industry as a whole has been using antibiotics responsibly for several decades, and there are strong beneficial arguments for their continued use. Responsible public policy demands a science-based approach be utilized in the decision making process before attempting to restrict or remove certain products due to overestimated risks. Part of this scientific review should include antibiotic use data, however this information has definite limitations and shortcomings which need to be understood before attempting to make any valid antibiotic resistance associations.     

Mathematical modeling and simulation in animal health. Part III: Using nonlinear mixed‐effects to characterize and quantify variability in drug pharmacokinetics

A common feature of human and veterinary pharmacokinetics is the importance of identifying and quantifying the key determinants of between‐patient variability in drug disposition and effects. Some of these attributes are already well known to the field of human pharmacology such as bodyweight, age, or sex, while others are more specific to veterinary medicine, such as species, breed, and social behavior. Identification of these attributes has the potential to allow a better and more tailored use of therapeutic drugs both in companion and food‐producing animals. Nonlinear mixed effects (NLME) have been purposely designed to characterize the sources of variability in drug disposition and response. The NLME approach can be used to explore the impact of population‐associated variables on the relationship between drug administration, systemic exposure, and the levels of drug residues in tissues. The latter, while different from the method used by the US Food and Drug Administration for setting official withdrawal times (WT) can also be beneficial for estimating WT of approved animal drug products when used in an extralabel manner. Finally, NLME can also prove useful to optimize dosing schedules, or to analyze sparse data collected in situations where intensive blood collection is technically challenging, as in small animal species presenting limited blood volume such as poultry and fish.     

Modes of action of growth promoting agents

The term growth promotion applies to the increase in performance or productivity achieved in food producing animals following the addition to their diet of feed antibiotics or growth promoters. Numerous methods are available for the different animal species. Steroidal substances are widely used in cattle whilst in pigs and poultry a wide range of substances are used to influence the gastro-intestinal microflora and thereby bring about a cost-effective improvement in productivity. Although certain antibiotics have been used for growth promotion for over three decades they are still highly effective and appear not to have reduced the value of other widely used antibiotics for the treatment of disease. The mechanisms by which growth promotion is produced are only poorly understood but it is now generally accepted that any improvement in performance is directly related to a variety of direct effects on the gut microbial flora and associated indirect effects on intestinal tissues. The direct effects include inhibition of bacterial growth, interference with bacterial cell wall development, induction of filament formation and interference with the metabolism of intestinal bacteria. The indirect effects include a reduction in the thickness of the intestinal mucosal layer and a decrease in the production of certain mucosal cell enzymes. Other effects seen in the gut of growth promoted animals and birds include a decrease in the prevalence of antibiotic resistance plasmids and a reduced frequency of plasmid transfer in enteric coliforms. It is clear from available data that conventional animals are depressed in performance and this depression can be alleviated by the administration of growth promoting agents in the diet of these animals. The lifting of this depression results in an improvement in performance especially daily live weight gain and feed conversion efficiency.     

中短链脂肪酸在无抗饲料中的应用

在现代畜牧业中,为了预防动物疾病和提高生产性能,普遍在饲料中使用抗生素。由于抗生素在畜牧业中的过度使用导致细菌耐药性的产生和抗生素的残留,严重影响到人类和畜禽的健康。因此,迫切地需要制定策略来替代抗生素用于生产食品的动物,特别是畜禽。中短链脂肪酸作为安全高效的添加剂已经畜牧生产中得到广泛的应用,文章以无抗饲料为背景,论述了中短链脂肪酸的研究进展和展望,为无抗饲料开发及使用提供参考。     

Strategies to modulate the intestinal microbiota and their effects on nutrient utilization,performance, and health of poultry

Poultry is widely produced and consumed meat global y. Its demand is expected to continue increasing to meet the animal protein requirement for ever-increasing human population. Thus, the chal enge that poultry scientists and industry face are to produce sufficient amount of poultry meat in the most efficient way. In the past, using antibiotics to promote the growth of poultry and manage gut microbiota was a norm. However, due to concerns over potential fatalistic impacts on food animals and indirectly to humans, their use as feed additives are banned or regulated in several jurisdictions. In this changed context, several alternative strategies have been proposed with some success that mimics the functions of antibiotics as growth promoters and modulate gut microbiota for their beneficial roles. These include the use of probiotics, prebiotics, organic acids, and exogenous enzyme, among others. Gut microbiota and their metabolic products improve nutrient digestion, absorption, metabolism, and overal health and growth performance of poultry. This paper reviews the available information on the effect of feed additives used to modulate intestinal microbiota of poultry and their effects on overal health and growth performance. Understanding these functions and interactions wil help to develop new dietary and managerial strategies that wil ultimately lead to enhanced feed utilization and improved growth performance of poultry. This review wil help future researchers and industry to identify alternative feed ingredients having properties like prebiotics, probiotics, organic acids, and exogenous enzymes.     

Food Safety Hazards and Microbiological Zoonoses in European Meat Imports Detected in Border Inspection in the Period 2008–2013

Microbiological contaminations and other food safety hazards are omnipresent within the European Union (EU) and a considerable risk for consumers, particularly in imported meat and meat products. The number of rejections at external EU borders has been increasing in recent years. Official authorities in each member state are therefore obliged to notify border rejections of food and animal feed due to a direct or indirect risk to human or animal health. This study explored the trends and temporal and spatial distribution of notifications on food safety hazards between January 2008 and December 2013 with a special emphasis on microbiological zoonoses in meat and meat products including poultry at border checks resulting from the rapid alert system for food and feed (RASFF). Results indicated that border rejection notifications are increasing exponentially, frequently due to Salmonella in poultry and shiga‐toxin‐producing E. coli in meat and meat products.     

微生物饲料添加剂在饲料中的应用及生产工艺

在现代规模化畜禽养殖生产中,腹泻已成为影响动物发育和生长的重要疾病之一,严重阻碍了养殖业的发展。尤其是幼小畜禽,如仔猪和雏鸡,腹泻已成为它们生长受阻和高死亡率的主要原因。目前的主要应对办法是在畜禽饲料中添加抗生素、激素、化学合成药物来防治畜禽的腹泻。但这样的结果导致病原微生物产生抗药性以及畜产品药物残留等问题的出现,因此通过微生物发酵生产的各种饲料添加剂,如益生素、抗菌素、维生素、氨基酸、酶制剂等,得到迅速发展。对微生物饲料添加剂在饲料中的应用及生产工艺进行了阐述。     

Backyard poultry: legislation,zoonoses and disease prevention

In law, backyard poultry are “food‐producing animals” and “farmed animals” and are subject to regulations regarding welfare, prescribing, banned procedures, disposal of carcases, feeding bans, notifiable diseases and disease surveillance in addition to those applying to most other pets. Many owners and some veterinary surgeons are unclear about the requirements of these regulations. Backyard poultry are also associated with some different zoonotic disease risks to mammalian pets. Because a high proportion of poultry morbidity and mortality relates to infectious diseases, the health of backyard poultry is amenable to improvement through basic husbandry, biosecurity, hygiene and preventive medicine measures that can be incorporated into a simple “flock‐health plan”. This article reviews these topics.     

氯霉素残留的危害及其检测方法

氯霉素属广谱抗生素 ,曾在畜牧业中广为应用。但氯霉素有较强的副作用和毒性作用 ,如果氯霉素在食用动物中残留 ,可通过食物链传给人类 ,长期微量摄入氯霉素 ,不仅使人体肠道正常菌群失调 ,而且还会引起多种疾病 ,对人类的健康造成危害。世界上许多国家禁止此药用于生产食品动物 ,并规定了在畜产品中氯霉素不得检出。对于氯霉素的残留 ,存在多种检测方法 ,不同的检测方法具有不同的检出限。检测限问题已成为关注的焦点 ,发达国家对检出限的要求越来越严格     

替代抗生素饲料添加剂研究进展

抗生素作为主要的饲料添加剂在几十年的广泛应用过程中造成了致病菌耐药性增强、动物免疫力降低、影响动物疫苗的效价、通过食物链影响人体健康等亟待解决的问题。我国农业农村部已发布公告,自2020年起我国饲料全面禁止添加使用抗生素类添加剂,饲料行业正式进入“无抗时代”。长期以来,研究人员积极寻求研发各种抗生素替代品及绿色无害的饲料添加剂,以消除或减轻禁用抗生素带来的一系列影响。就目前主要抗生素替代品的抗菌特点及抗菌机理进行综述,旨在为“禁抗”后抗菌性添加剂在饲料中的应用提供参考。     

饲料“禁抗”势在必行，行业如何应对？

抗生素自问世以来,在防治动物疾病、促进畜禽健康生长,提高养殖效益方面发挥了重要作用。但随着抗生素的不规范使用甚至滥用,药物残留和动物源细菌耐药性等问题逐渐浮出水面,给动物源性食品安全和公共卫生安全带来风险隐患。对此,农业农村部发布公告,实施促生长类药物饲料添加剂退出行动(简称饲料"禁抗")。从长期发展来看,饲料"禁抗"对行业可持续发展有积极正向作用,但短期对饲料养殖行业会带来一定的冲击。饲料"禁抗"是提高动物源性食品安全和公共卫生安全水平,促进畜牧业持续健康发展的必然要求,无论是饲料企业,还是养殖场户,应以冷静积极的心态面对,积极找寻饲用抗生素减量替代方案,并加速推广应用,以助力养殖业绿色健康发展,满足人们对安全优质动物源性食品的需求。     

High‐Level Ciprofloxacin‐Resistant Campylobacter jejuni Isolates Circulating in Humans and Animals in Incheon,Republic of Korea

Campylobacter jejuni is one of the major causative pathogens of outbreaks or sporadic cases of diarrhoeal diseases worldwide. In this study, we compared the phenotypic and genetic characteristics of C. jejuni isolates of human and food‐producing animal origins in Korea and examined the genetic relatedness between these two groups of isolates. Regardless of isolation source, all C. jejuni isolates harboured four virulence genes, cadF, cdtB, ciaB and racR, whereas the wlaN and virB11 genes were more frequently observed in human isolates. Antimicrobial susceptibility testing showed that the majority of C. jejuni isolates displayed high‐level resistance to fluoroquinolone (95.2%) or tetracycline (76.2%) antibiotics, and 12.4% of isolates exhibited multidrug resistance (more than three classes of antibiotics tested). Pulsed‐field gel electrophoresis (PFGE) of all Campylobacter isolates revealed 51 different SmaI‐PFGE patterns and six major clusters containing both human and animal isolates. These results indicate that genetically diverse strains of C. jejuni with antimicrobial drug‐resistance and virulence properties have prevailed in Incheon. Nevertheless, some particular populations continue to circulate within the community, providing the evidence for an epidemiological link of C. jejuni infections between humans and food‐producing animals. Therefore, the continued monitoring and surveillance of C. jejuni isolates of human and food‐producing animal origins are required for public health and food safety.     

Antibodies: Alternatives to Antibiotics in Improving Growth and Feed Efficiency

The consolidation of poultry since the 1950s largely depended upon two primary management tools: vaccination and antibiotics. These two tools allowed for the prevention of both bacterial and viral infections that could greatly impact poultry raised in large numbers. Antibiotics were also found to improve poultry growth and feed efficiency over 10% when fed below therapeutic levels. Hence, by the late 1950s, the use of antibiotics for improving growth and feed efficiency in consolidated poultry flocks was commonplace. Early in the discovery of antibiotics, the development of resistance was always a concern, particularly in humans’ consuming animal products that were fed antibiotics. While science never conclusively supported this concern, advocate groups persuaded users of poultry products to avoid foods derived from animals fed antibiotics. Scientists studied the theories supporting the mechanism(s) by which antibiotics improve growth. Products to improve animal performance in the absence of antibiotics have included: enzymes, competitive microbial species, precolonization of the gastrointestinal tract with favorable microbial species, and dietary additives that inhibit microbial attachment to the intestinal mucosa. A recent addition to dietary substances that improve growth and feed efficiency in poultry and other species are egg antibodies that specifically target processes involved in the immune regulation of growth. Antibodies to neuropeptides and the rate-limiting enzyme, phospholipase A₂, in eicosanoid synthesis are presented, along with the hypothesized mechanism of action. Evidence suggested that egg antibodies offer a new strategy in improving the efficiency of animal performance.     

Role of genetically engineered animals in future food production

Genetically engineered (GE) animals are likely to have an important role in the future in meeting the food demand of a burgeoning global population. There have already been many notable achievements using this technology in livestock, poultry and aquatic species. In particular, the use of RNA interference (RNAi) to produce virus‐resistant animals is a rapidly‐developing area of research. However, despite the promise of this technology, very few GE animals have been commercialised. This review aims to provide information so that veterinarians and animal health scientists are better able to participate in the debate on GE animals.     

Visual and auditory cues facilitate cache pilferage of Siberian chipmunks (Tamias sibiricus) under indoor conditions

In the struggle for survival, scatter‐hoarding rodents are known to cache food and pilfer the caches of others. The extent to which rodents utilize auditory/visual cues from conspecifics to improve cache‐pilfering is unknown. Here, Siberian chipmunks (Tamias sibiricus) were allowed to search for caches of Corylus heterophylla seeds (man‐made caches and animal‐made caches) after experiencing cues from a conspecific's cache‐searching events. For each type of cache, 3 experimental scenarios were presented: (1) alone (control); (2) auditory/visual (hearing and seeing conspecific's cache‐searching events); and (3) auditory only (hearing conspecific's cache‐searching events only) with random orders. The subjects located man‐made caches faster, harvested more caches, and hoarded more seeds both in the auditory/visual and the auditory only treatments compared to the control, while scatter‐hoarding more seeds in the auditory/visual treatment but larder‐hoarding more seeds in the auditory only treatment. Compared to the control, the animals spent less time locating animal‐made caches, harvested more caches, ate fewer seeds, larder‐hoarded more seeds and hoarded more seeds in total both in the auditory/visual and the auditory only treatments, while eating more seeds and hoarded fewer seeds in total in the auditory only treatment than in the auditory/visual treatment. The results also show that females spent less time locating the animal‐made caches, but they scatter‐hoarded fewer seeds than males in the auditory/visual treatment. To the best of our knowledge, this is the first report that visual and/or auditory cues of conspecifics improve cache‐pilfering and hoarding in rodents.     

Poultry husbandry and animal health

Close interactions are existing between poultry husbandry and poultry health. The more housing systems and the environment of the animals can be controlled, the less the general risk of disorders in poultry flocks--especially of diseases which are caused by the introduction of microoganisms. Resulting deterimental effects will affect not only the animals themselves, but also pose a risk indirectly for humans via food originating from animals under production. Also, by keeping the risk of infections as low as possible, the use of therapeutics can be avoided. This will reduce the risk of residues in food of animal origin. In summary, with all probability open poultry husbandry systems, especially those including free range systems pose increased risks for poultry health and consequently for the quality of food originating from poultry production. At least, those systems require highest standards of biosecurity, defined as management, location, farm layout, cleaning and desinfection incl. pest control programs, immunization and specific veterinary monitoring concepts to prevent infections.     

丁酸梭菌的功能性研究进展及其在畜禽生产中的应用

丁酸梭菌（Clostridium butyricum）又名丁酸梭状芽孢杆菌、酪酸梭菌,是一种产丁酸、乳酸和乙酸的厌氧异养的革兰氏阳性芽孢杆菌,具有耐高温、耐酸和耐多种抗生素等生物学特性。丁酸梭菌定植于畜禽肠道,可抑制肠道有害菌的生长,同时促进有益菌的增殖,有效提高畜禽对营养物质的消化吸收及其抵抗力,进而提高畜禽养殖经济效益。丁酸梭菌存在于土壤或健康动物的粪便中,具有绿色、无残留、安全性好,以及稳定性及耐药性强等特点,是一种具有广泛开发潜力的绿色添加剂。作者主要介绍了丁酸梭菌的特性,简述了其对畜禽肠道形态、肠道屏障、肠道菌群、免疫等方面的影响,回顾了近十年来丁酸梭菌在畜禽生产中的应用进展,并探讨了其在生产应用中的问题,以期为丁酸梭菌的进一步应用提供理论依据。     

Monitoring of antibiotic consumption in livestock: a German feasibility study

Every application of antibacterial drugs in veterinary medicine may encourage selection for resistant bacteria. In Germany no valid data are available which would be suitable for a species specific estimation of drug consumption especially regarding food producing animals. Therefore, a representative monitoring of consumption of antibacterial drugs in food producing animals should be implemented. As a first step, a feasibility project was conducted to identify the technical preconditions and develop a concept for a regular monitoring system within Germany as a country with a non-central federal state system. The data were collected via the forms obligatory by German law concerning the treatment of animals and the delivery of animal drugs to the animal owners by the veterinarian. 24 veterinary practices and 65 farmers were visited, and all applications of antibiotics to farm animals during the course of one year (September 1, 2006 to August 31, 2007) were entered into a central database. A total of 95,584 records were collected and analysed statistically. Consumption of antibiotics was calculated in kg, but also the number of applications was analysed. The consumption of tetracyclines in kg reached 54.3% of all antimicrobial substances applied to pigs, but only 25.7% of all doses applied to pigs were tetracyclines. For the farms' data, the number of daily doses per animal year (DD(ay)) was estimated based on the number of daily doses recorded and on the number of animals kept in the farm. Correct and detailed data regarding the structures of the farms as well as of veterinary practices are necessary to estimate the consumption of antibiotics reliably. The proposed system is able to function as a monitoring system for antibiotic use in Germany, when the monitoring data are linked to the agricultural data (farm sizes) accounting for differences between German regional agricultural and animal husbandry structures. Furthermore, the results of the antibiotic use analyses may serve as basis to assess the results of the sales data of the pharmaceutical industry. Results are comparable to the outcome of respective systems in other European countries, e.g. the Netherlands and Denmark, and therefore it will contribute to a better understanding and development of strategies for the control of antimicrobial resistances on the European level.     

Characterization of antibiotic-resistant bacteria in rendered animal products.

Antibiotics are used in food animal production to treat diseases and also to improve performance. Antibiotics are not used on all farms, and antibiotic resistance is occasionally found on farms that do not use antibiotics. Rendered animal protein products are often included in poultry feeds and could potentially serve as a source of antibiotic-resistant bacteria. One hundred sixty-five rendered animal protein products from cattle, poultry, and fish were aseptically collected from poultry feed mills. Fifty-five percent of the poultry meal samples had detectable levels of gram-negative bacteria ranging from 40 to 10,440 colony-forming units/g of sample. Poultry meal and meat and bone meal had the greatest number of samples with bacteria resistant to five or more antibiotics. A high percentage of feed samples (85%) contained bacteria resistant to amoxicillin, ampicillin, clavulanic acid, or cephalothin, whereas few samples contained bacteria resistant to ciprofloxacin, kanamycin, or trimethoprim/sulfamethoxazole. Acinetobacter calcoaceticus, Citrobacter freundii, and Enterobacter cloacae were the most commonly isolated antibiotic-resistant bacteria. Isolation for Salmonella was also performed, with 14% of the meat and bone meal samples containing Salmonella sp. Only one of the meat and bone meal isolates, Salmonella livingstone, was resistant to five or more antibiotics. Many of the antibiotic-resistant bacteria contained integrons, genetic elements that mediate multiple drug resistance.     

绿色荧光蛋白技术在益生菌研究中的应用前景

畜禽生产中,抗生素的不合理使用在畜禽产品中极易形成抗生素残留超标的安全隐患,不仅威胁人类健康,也制约着养殖业的可持续发展。益生菌正是在这种情况下作为抗生素的有效替代品应用于动物饲料中。但是,有关益生菌制剂发挥益生作用的机理还不是很清楚,而通过现代生物技术对有益菌株进行遗传标记,是研究和阐明其在动物体内作用机理的重要技术手段和有效途径之一。绿色荧光蛋白（green fluorescent protein,GFP）作为新的报告系统,已开始逐渐应用于饲用微生物的动态监测和作用机理研究中,且已表现出良好的应用前景。