Characterization of transgenic livestock production

The objective of transgenic livestock improvement projects is to develop and bring to market superior breeding stock, as well as germplasm for the artificial insemination and embryo transfer industries. Livestock animal biotechnology programs hold the promise of achieving, in a single generation, improvements in commercially important livestock species previously possible only through long-term traditional selective breeding practices or by chance mutation. Transgenic farm animals harboring growth hormone or metabolically related structural genes have been created. Studies of these animals demonstrate the effects of inadequate regulation of transgene expression. Research continues to explore the intricacies of developmental regulation of such genes and phenotypic consequences of mammalian gene transfer. Ultimately, genetically engineered livestock will provide producers with the benefit of increased production efficiencies while the consumer will have healthier animal food products. Conceivably, products will be produced with lower levels of fat, cholesterol, feed additives and pharmaceutical residues from animals with altered carcass composition that will result in greater nutritional benefit for the consumer.     

New Biotechniques and their Consequences for Farm Animal Welfare

Contents This paper considers (potentially) harmful consequences of new biotechnologies for farm animal welfare. The most important new biotechnologies that are currently used in farm animals breeding and husbandry include: multiple ovulation and embryo transfer (MOET) and in vitro embryo production (IVP). Cloning by nuclear transfer (NT) and transgenesis are still in development and mainly applied for experimental purposes with the prospect of a more widespread practical implemention in the future. Evidence is presented showing that generally accepted technologies such as MOET and IVP, relative to in vivo procedures, can result in a host of deleterious side-effects commonly known as the large offspring syndrome (LOS). Likewise, NT and transgenesis, which also typically include several in vitro reproductive manipulations, have clearly been associated with the occurrence of LOS symptoms. It is argued that transgenesis may constitute one additional set of factors that may negatively affect farm animal welfare: the expression of the transgene and the concomitant synthesis and release of a protein. NT might lead to incompletely reprogramming of the transferred genome. It is suggested that the introduction of new biotechnologies into farm animal husbandry should be accompanied by scientifically valid and systematic studies into the effects on animal welfare, with the help of a comprehensive welfare protocol.     

Advances in farm animal transgenesis

The first transgenic livestock were produced in 1985 by microinjection of foreign DNA into zygotic pronuclei. This was the method of choice for more than 20 years, but more efficient protocols are now available, including somatic cell nuclear transfer and lentiviral transgenesis. Typical applications include carcass composition, lactational performance and wool production, as well as enhanced disease resistance and reduced environmental impact. Transgenic farm animal production for biomedical applications has found broad acceptance. In 2006 the European Medicines Agency (EMA) approved commercialization of the first recombinant pharmaceutical protein, antithrombin, produced in the mammary gland of transgenic goats. As the genome sequencing projects for various farm animal species are completed, it has become feasible to perform precise genetic modifications employing the emerging tools of lentiviral vectors, small interfering ribonucleic acids, meganucleases, zinc finger nucleases and transposons. We anticipate that genetic modification of farm animals will be instrumental in meeting global challenges in agricultural production and will open new horizons in biomedicine.     

Safeguarding herds from the animal hygiene point of view

One of the most important concepts for the protection of herd health is the implementation of structural and organisational measures to prevent infective agents and other adverse compounds from entering the farm. Safeguarding health, well-being and production efficiency is part of the overall management concept of hygiene in animal production systems. This paper presents an overview of the most important rules and recommendations to protect livestock production facilities from the intrusion of infectious pathogens, beginning with the right choice of the site for the farm and the animal housing ("safe distances" to neighbouring farm animal houses), solid fencing and control and disinfecting places at the entrance gate. The traffic of vehicles and people transporting animals, feedstuff, equipment and slurry or manure to and from the facility should be reduced to a minimum. Fallen animals should be stored in separate and safe containers until removed by specialised companies. Regular control of rodents, insects and wild birds is crucial to avoid the transfer of infectious agents from farm to farm and between herds within a farm. Equally important factors are the health status of personnel to avoid transmission of zoonotic diseases, the application of the all-in-all-out system and a strict cleaning and disinfecting regime. The internal and external organisational measures for preventing the spread of infections in animal production will gain increasing importance in the future because the farm animal producer bears the responsibility for the production of safe and healthy food at the primary segment of the food chain. Increasing restrictions on the use of veterinary drugs for food delivering animals will increase the importance of prophylaxis, prevention and protection of production units as the keys for safeguarding health, well-being and efficiency of farm animals. Only the application of strict hygiene principles in animal production will make it possible to meet the consumer demand for safe and high quality food of animal origin.     

Risk assessment of endocrine-active compounds in feeds

As a key element of the 'farm-to-fork' approach, an assessment of the safety of feed components should consider major long-term toxicological hazards, such as endocrine disrupting chemicals (EDCs). In this review, attention is given to endocrine-modulating trace elements (such as iodine and trivalent chromium) and their potentially sensitive subgroups as nutritional feed additives from the standpoint of farm animal safety and consumer exposure. Feedstuffs can be a major vehicle for persistent EDCs, such as polychlorinated biphenyls, and potential risks include fish farming and ruminants grazing in polluted areas. Limited data still exist on the feed-to-food transfer of other EDCs, such as brominated flame retardants. EDCs of vegetable origin (e.g. zearalenone and isothiocyanates) can have a greater adverse impact on farm animals than environmental xenobiotics but the risk of carry-over to consumers appears low. Topics for further research are suggested, including the need for more refined exposure data, characterization of biomarkers for long-term effects, xenobiotic-nutrient interactions and the search for novel feed ingredients that are less vulnerable to contamination.     

Transgenesis may affect farm animal welfare: a case for systematic risk assessment

This paper considers (potentially) harmful consequences of transgenesis for farm animal welfare and examines the strategy of studying health and welfare of transgenic farm animals. Evidence is discussed showing that treatments imposed in the context of farm animal transgenesis are by no means biologically neutral and may compromise animal health and welfare. Factors posing a risk for the welfare of transgenic farm animals include integration of a transgene within an endogenous gene with possible loss of host gene function (insertional mutations), inappropriate transgene expression and exposure of the host to biologically active transgene-derived proteins, and in vitro reproductive technologies employed in the process of generating transgenic farm animals that may result in an increased incidence of difficult parturition and fetal and neonatal losses and the development of unusually large or otherwise abnormal offspring (large offspring syndrome). Critical components of a scheme for evaluating welfare of transgenic farm animals are identified, related to specific characteristics of transgenic animals and to factors that may interact with the effects of transgenesis. The feasibility of an evaluation of welfare of transgenic farm animals in practice is addressed against the background of the objectives and conditions of three successive stages in a long-term transgenic program. Concrete steps with regard to breeding and testing of transgenic farm animals are presented, considering three technologies to generate transgenic founders: microinjection, electroporation and nuclear transfer, and gene targeting including gene knockout. The proposed steps allow for unbiased estimations of the essential treatment effects, including hemi- and homozygous transgene effects as well as effects of in vitro reproductive technologies. It is suggested that the implementation of appropriate breeding and testing procedures should be accompanied by the use of a comprehensive welfare protocol, specifying which parameters to monitor, at which stages of the life of a farm animal, and in how many animals. Some prerequisites and ideas for such a protocol are given. It is anticipated that systematic research into the welfare of farm animals involved in transgenesis will facilitate the use of the safest experimental protocols as well as the selection and propagation of the healthiest animals and, thereby, enable technological progress that could be ethically justified.     

Implications of intensification of pastoral animal production on animal welfare

The intensification of pastoral animal production results from several major developments including increased forage production and utilisation, diet supplementation, breeding animals to increase milk, meat or wool production, and changes in management. The impact of increased intensification on welfare will differ across species and systems. More intensive-grazing systems and the feeding of novel forages will underpin all moves to intensification. More intensive grazing generally reduces opportunities for shade and shelter. Improved nutrition will generally benefit welfare but competition for available feed may cause increased social pressure. Increased flock and herd size will be associated with a reduction in the human:animal ratio and less time to observe individual animals. Remote monitoring of activity and health might counter this impact.

Intensification of dairy production will result in larger herds, more year-round milking, robotic milking, use of housing and yards year round, and total mixed-ration feeding. Larger herds mean longer distances to walk to and from the dairy shed, and more lameness and less time to spend on self-maintenance activities such as grooming. Holding and feeding dairy cows on yards will cause an increase in lameness and mastitis and perhaps an increase in agonistic behaviour but will reduce time spent walking. Intensification of sheep production will involve increased flock size, increased fecundity, breeding from hoggets, and breeding ewes all year round. Housing during lambing might be considered appropriate, as would feeding to lift milk yields. Increased fecundity with an increase in triplets will increase lamb mortality rates, but housing ewes, when managed well, will result in reduced lamb mortality. Intensification of lamb finishing will be by improved nutrition. Intensification of beef production will include more breeding of heifers at 15 months, and more problems with dystocia.

Intensification of pastoral production will have positive and negative effects on animal welfare. The balance will be determined by the quality of management and stockmanship, and the pressure on businesses to be profitable.     

肉牛遗传育种与繁殖技术发展趋势

肉牛业是畜牧业的重要组成部分,而良种产业化是肉牛产业发展的关键。20世纪人工授精、胚胎移植、发情控制等繁育技术的出现及常规育种技术的应用,使肉牛遗传改良取得了巨大进展,但越来越不能满足现代肉牛业发展的需求。进入21世纪,随着现代生物技术的迅速发展,肉牛育种已从传统表型和表型值育种朝着分子水平方向发展;以配子与胚胎工程、基因工程为主体的高新繁育技术将逐渐成为肉牛繁育的主要手段;体外胚胎生产、胚胎移植商业化应用将会进一步提高,实现产业化;动物克隆、转基因动物生产经不断发展与完善,将成为肉牛育种方面最具潜力的方法。论文就肉牛育种与繁育技术的发展趋势作一简要论述,旨在为肉牛生产提供理论依据与参考。     

Buffalo (Bubalus bubali) Late Embryo and Foetus Development: A Morphological Analysis

Many researches describe the embryonic developmental features in domestic animals; however, in farm animals, they are scarce. Most farm animal studies are related to assisted reproduction and embryos transfer techniques. But, morphological features and size measure to estimate the age gestation are rarely reported in literature. Thus, in this study, we described the developmental changes in the bubaline (Bubalus bubali) concepts from 21 to 60 days of gestation. Our results revealed that buffalo embryos similar morphological characteristics similar to other mammalian species. Also, similarities between bovine and bubaline persist; except on foetal stages when buffalos have a faster development than bovine. Therefore, buffalo's gestation period exhibits some varieties and accurate embryo age is more difficult. Yet, when we use a combination of the crown–rump, macroscopic analysis and alizarin red, it is possible to describe better the whole embryogenesis stages of the buffalo and which can contribute for future reproduction researches and applications in veterinary practice.     

哺乳动物胚胎玻璃化冷冻研究进展

近40年来,利用冷冻保存技术将哺乳动物胚胎长期保存起来,建立"胚胎库"是保护物种资源和拯救濒危动物的有效手段,同时也是加快家畜品种改良、建立动物基因库和实施胚胎移植产业化的重要组成部分,也可以为克隆、转基因等现代生物技术提供丰富的试验材料,使胚胎的供给不受时间和空间的限制。胚胎冷冻保存技术在人类辅助生殖方面也具有广阔的应用前景。本文主要介绍了玻璃化冷冻过程中胚胎冷冻主体承载工具特点和应用,并展望未来哺乳动物胚胎冷冻发展的方向。     

Aspects of animal welfare in livestock production

The modern consumer is increasingly concerned about the welfare of farm animals which are kept in intensive systems on specialised farms where the health and well-being is almost completely dependent on the will, ability and care of the farmer. Further demands related to animal production are consumer health (quality and safety of food products), the protection of the environment and cheap food. The currently used husbandry systems are man made and emphasise automation which requires permanent critical observation of the welfare of the animals. Ethological indicators are equally important as health and performance to evaluate keeping systems. Future animal farming will be influenced by new technologies such as electronic animal identification and milking robots, and more important by biotechnology and genome analysis. Veterinary surgeons and farmers have to co-operate on the basis of scientifically sound animal welfare schemes which help to protect our farm animals in modern and intensive livestock production systems.     

Physiological adaptation to the environment

The ability of an animal to cope with new environments arises from its capacity to respond to environmental variables and maintain body equilibrium (homeostasis). Each compensating mechanism depends on, and is a part of, a physiological feedback process. The severity (intensity and duration) of an environmental change relative to the animal's capacity to respond determines the potential disruption to the animal's equilibrium and the resources that must be invested to regain homeostasis. However, an environmental change sufficient to seriously challenge one individual may be insufficient to produce a measurable response in another. The principles behind the responses occurring in animals as a consequence of a change in their physical environment are illustrated in this review by examples drawn from responses of animals to cold stress. Behavioral opportunities sometimes are constrained in farm animals, and internal metabolic responses tend to become more prominent in such situations. Furthermore, as a disturbing factor persists, the immediate defensive responses are replaced by longer-term and adaptive mechanisms that reduce the burden on the animal. As we gain greater understanding of the environment-animal interface and the sensitivity and response of animals to disruption, we will be better able to establish and maintain suitable environments for our farm animals.     

哺乳动物卵母细胞孤雌激活的研究

研究哺乳动物卵母细胞的激活及孤雌胚发育,对了解哺乳动物早期胚胎发育、深入细致地研究核移植技术和动物克隆技术、建立生产孤雌哺乳动物品系及加速家畜育种进程等均具有重要意义。本文主要从卵母细胞孤雌激活的机制及影响因素、不同动物卵母细胞的激活、提高卵母细胞孤雌激活效果的技术途径以及对孤雌激活的研究意义和发展前景等方面作了详尽论述,为同类研究提供参考。     

Future directions in the European union for veterinary education as related to food-producing animals, with special reference to Greece

During the past 50 years, procedures for raising food-producing animals have changed. Intensification of food production was necessary to keep prices low and to fulfill market demands for the continuously increasing worldwide population. Intensification of farming procedures produced many new problems, some of which had a considerable impact on public opinion about how animals are raised and how food of animal origin is produced and preserved. "Man made diseases" of animals such as bovine spongiform encephalopathy (BSE); contamination of foods with dioxins either through contamination of animal feeds or from the environment; and increased microbial resistance to drugs used for treatment, for prophylaxis of animals from infectious agents, and for growth promotion are some well-known hazards of intensified farming. Veterinarians working on food-producing animals are faced with an increased demand for foods of high quality and safety in developed countries, and higher quantities in the rest of the world. These qualitative and quantitative changes indicate that they must adjust to these new conditions. They will be most successful if their education is adjusted to meet the challenges that the public has created for them through new concepts of the production of food of animal origin. One such concept is the production of foods under fully certified procedures from the farm to the consumer's table. Food safety measures protecting public health will better be achieved if the education of the future veterinarian includes the principles of Hazard Analysis Critical Control Points (HACCP) starting at farm level. This article provides some market-driven ideas in this direction for European Union (EU) countries, including Greece.     

Ochratoxin A in feed of food-producing animals: an undesirable mycotoxin with health and performance effects

Mycotoxins are secondary fungal metabolites, whose presence in feed- and foodstuffs is unavoidable. Ochratoxin A (OTA) is one of the known mycotoxins with greatest public health and agro-economic significance. Several toxic effects have been ascribed following exposure, namely nephrotoxicity, as well negative impacts in the performance of farm animals, resulting in major economic implications. Of no less importance for the route of human exposure that can also embody the carry-over of OTA from feed into animal-derived products is also a concern. For all these reasons the present article updates the worldwide occurrence of OTA in different raw ingredients and finished feed destined to food-producing animals. After that a brief characterization of specie susceptibility and the major rationales is made. An historical overview of field outbreaks linked to OTA exposure in farm animals, concerning the implicated feeds, contamination levels and major clinical and productivity effects is presented. Finally a review of the major animal health and performance potential impacts of animals being reared on contaminated feed is made allied to a perspective regarding its co-occurrence with other mycotoxins, and simultaneous parasitic and bacterial infections. Ultimately, this article aims to be instructive and draw attention to a mycotoxin so often neglected and elapsed from the list of differential diagnosis in farm practice. For the unpredictability and unavoidability of occurrence, OTA will definitely be an enduring problem in animal production.     

中国水牛遗传育种研究进展

我国水牛遗传育种的研究主要集中在染色体核型、蛋白质多态性、水牛胚胎体外生产与胚胎移植技术等方面。本文从中国水牛的类型和分布特征、遗传特性的研究现状、现代生物技术在水牛育种中的应用、中国水牛育种研究前景及展望等四个方面综述水牛的育种进展,认为以现代生物技术为核心的分子育种将成为水牛育种的总趋势,为我国水牛的产业化发展提供了理论依据。     

餐厨废弃物饲料化技术及其在动物生产中的应用

餐厨废弃物(food waste,FW)的资源利用受到广泛关注。FW焚化、填埋、堆肥、厌氧消化等技术因其面临的环境可持续性问题而受到越来越多的批评。饲料化技术可以将FW转化为高价值的饲料,从而减少固体废物的排放、养殖成本和环境污染,但该技术应符合减少、再利用和回收有机废物的处理原则。作者综述了FW的饲料化技术及其在动物生产中的应用。FW饲料化技术主要包括热处理、酶处理、藻类培养、昆虫过腹、发酵技术。其中热处理可以确保微生物安全性,是其他技术的预处理技术。藻类培养和昆虫过腹技术可以将FW转化为植物和昆虫蛋白,避免同源污染,但尚不清楚藻类和昆虫在FW利用过程中是否会造成污染物积累。酶处理和发酵技术可以将FW中大分子转化为小分子。酶的催化性能和稳定性容易受外界条件的影响,需要考虑特殊的酶制剂。发酵技术的机械化程度和资源利用率高,其核心是微生物,需要筛选有效的、能充分利用FW的微生物。目前FW在畜牧业中的应用较少,在其生产和应用中要特别注意用量和使用时间。为了使FW饲料真正作为动物饲料进入食物链,研究人员必须对不同动物(含不同生长阶段)的生长性能和产品特性进行研究,以确保动物健康及动物产品对人类健康没有负面影响。