Risk of introduction of BSE into Japan by the historical importation of cattle from the United Kingdom and Germany

All cattle of UK and German origin imported to Japan since 1980 and slaughtered before 2002 were traced (n = 33 and 15 respectively) and the probability that none, one, two or three of these imported cattle had developed BSE (reached the end or last stage of incubation period) at the year of slaughter/death was calculated. The predicted risk that BSE was introduced into Japan by imported cattle was 0.18. Among cattle imported from these countries in various years, cattle imported from the UK in 1987 and 1988 presented the highest risk, while the risk that BSE entered Japan by live cattle imported from the UK in 1982 and from Germany in 1993 was negligible. Because there was no effective system to avoid the recycling of the BSE agent, those infected cattle imported from the UK in 1987 and 1988 most probably entered the feed chain in Japan in 1992 and 1993.     

Risk assessment and surveillance for bovine spongiform encephalopathy (BSE) in Argentina

An assessment was made of the risks of bovine spongiform encephalopathy (BSE) occurring in Argentina. Most of the factors associated with the origin and development of the BSE epidemic in the UK are essentially absent. For example, Argentina's large sheep and cattle industries are based on low-cost production systems using grass. Concentrated feeds are not used for sheep, rarely for beef cattle and to a comparatively modest extent for dairy cows. Particularly important are the facts that scrapie (and BSE) has never been reported in Argentina—very small amounts of waste tissues from sheep are rendered to produce meat and bone meal (MBM)—and MBM is not used in concentrated feeds for cattle. We conclude that Argentina has an exceptionally low risk of BSE due to scrapie. There is a very small risk of BSE having been introduced via live animals imported from countries with BSE, but this could only give rise to isolated cases because MBM is not fed to cattle.

A surveillance programme has been carried out based largely on a histological examination of brains from three categories of old dairy cows: animals reported on the suspicion of having neurological disease; animals in poor condition at slaughter; healthy animals randomly selected in the abattoir. No evidence of transmissible spongiform encephalopathy was seen in several sections from each of a total of 1019 brains. We conclude that, for most practical purposes, Argentina may be considered to be free from BSE.     

Geographical BSE risk assessment and its impact on disease detection and dissemination

Bovine Spongiform Encephalopathy (BSE) rapidly evolved into an issue of major public concern particularly when, in 1996, evidence was provided that this disease had crossed the species barrier and infected humans in the UK with what has become known as "variant Creutzfeldt Jakob Disease" (vCJD). The aim of this paper is to describe the European Geographical BSE risk assessment (GBR) that was successfully used for assessing the qualitative likelihood that BSE could be present in a country where it was not yet officially recognized. It also discusses how this can lead to risk-based and therefore preventive management of BSE at national and international levels. The basic assumption of the GBR method is that the BSE agent is initially introduced into a country's domestic cattle production system through the importation of contaminated feedstuffs or live cattle. This is referred to as an "external challenge". The ability of the system to cope with such a challenge is, in turn, referred to as its "stability": a stable system will not allow the BSE agent to propagate and amplify following its introduction, while an unstable system will. The BSE-status of a country assessed by this system was used by the European Commission as the basis for trade legislation rules for cattle and their products. The GBR was an invaluable tool in evaluating the potential global spread of BSE as it demonstrated how a disease could be transferred through international trade. This was shown to be a critical factor to address in reducing the spread and amplification of BSE throughout the world. Furthermore, GBR resulted in the implementation of additional measures and management activities both to improve surveillance and to prevent transmission within the cattle population.     

Development of discrimination markers between Japanese domestic and imported beef

In the meat industry, correct labeling of beef origins or breed is required to assure quality and safety. This paper describes the development of discrimination markers between Japanese domestic and imported beef from the United States (US) and Australia (AUS) based on a bovine 50K single nucleotide polymorphism (SNP) array using a total of 110 samples: Japanese Black (n = 50), Japanese Holstein (n = 50) and US cattle (n = 10). Genotyping information revealed 1081 SNPs as candidate markers that were polymorphic only in US cattle. The genotyping results by PCR – restriction length polymorphism in Japanese Black (n = 300) and Holstein cattle (n = 146) revealed that 11 SNPs had alleles specific to US cattle. Their allelic frequencies in US cattle (n = 108) ranged from 0.097 to 0.250 with an average of 0.178 and the combined identification probability of US cattle was 0.987. In addition, we also verified the applicability of these US‐specific markers to AUS cattle. Their allelic frequencies in AUS cattle (n = 280) ranged from 0.063 to 0.224 with an average of 0.137 and the combined identification probability of AUS cattle was 0.963. In conclusion, a set of these markers could be useful for discriminating between Japanese domestic and imported beef and would contribute to identify origins and prevent falsified labeling of beef.     

Area-level risks for BSE in British cattle before and after the July 1988 meat and bone meal feed ban

In this paper we investigate area-level risk factors for BSE for the cattle population present in Great Britain between 1986 and 1997. By dividing this population into two birth cohorts, those born before the July 1988 ban on feeding ruminant-derived meat and bone meal to ruminants and those born after, second-order regional influences are distinguished from the strong first-order south-to-north gradient of area-level BSE risk using Bayesian hierarchical models that account for structured (spatially correlated) and unstructured heterogeneity in the data. For both cohorts area-level risk of BSE was increased by a more southerly location and greater numbers of dairy cattle, relative to non-dairy cattle. For the cohort of cattle born after the July 1988 ban on feeding ruminant-derived meat and bone meal area-level BSE risk was additionally associated with greater numbers of pigs, relative to cattle. These findings support the role of low level cross-contamination of cattle feed by pig feed as an influence on BSE incidence risk as the epidemic evolved. Prior to the 1988 meat and bone meal ban unexplained BSE risk was relatively uniformly distributed across the country whereas after the ban there were spatially aggregated areas of unexplained risk in the northern and eastern regions of England suggesting that local influences allowed BSE control measures to be less-successfully applied in these areas, compared with the rest of the country. We conclude that spatially localised influences were operating in divergent ways during the two phases of the epidemic.     

Impact of BSE on livestock production system

The small number of BSE cases diagnosed in Italy from January 2001 to 12 September 2001 (a total of 28, one every 9000 head) does not allow for a statistical analysis of the relationship between this disease and the livestock systems. However, some indications can be noted: (a) only dairy cattle, which represent three-quarters of the cattle raised in Italy, are involved; (b) 58% of the cases belong to medium-large farms that breed 27% of all head; (c) 13 out of 28 cases are 5-year-old animals and 26 out of 28 are between 5 and 7 years of age; (d) 15 of 28 cases come from Lombardia, where 27% of Italian dairy cattle are raised. The following factors may have affected the livestock system: (1) trends of beef meat consumption; (2) changes in livestock management; (3) changes in animal feeding; (4) possible effects on selection. A strong decline in beef meat consumption (4 kg/year) has been observed in the UK and other European countries since 1996 (the year of the discovery of the relationship between BSE and nvCJD). In Italy, from January 2001 the consumption of beef meat has declined as well as slaughter: a drop of 31% in the total slaughtered head in the period January-February, a drop of 14% in January-May. A fall in the price of calves has promoted, in some dairy farms, the start of the production of light beef less than one year old (advantages in the marketing of meat favour this initiative), a phenomenon which is not yet well established. Traceability and certification of meat have improved, thanks to breeders' associations and interprofessional agreements. The breeders associations have also started insurance initiatives against BSE risks. In Italy the employment of plant protein meals would increase the total feedstuff consumption by about 7%. Direct effects of BSE could slow down the genetic progress (GP) of cattle populations within breed and country. Indirect effects on GP may also happen as a consequence of an increase in the replacement rate (rr). This increase in rr reduced the generation interval and will therefore proportionally increase GP. Some important questions for the livestock production system are: Does the vertical transmission of BSE exist? Is there a genetic basis favouring the disease and is it inheritable? Are in vivo diagnostic tests possible? Are vaccination schemes against BSE possible and useful or is it better to pursue eradication?     

Where does BSE in the Netherlands come from?

It is only in the last 5 years that the Netherlands has been confronted with cases of bovine spongiform encephalopathy (BSE). The cases diagnosed to date have not been clearly linked to imports from the United Kingdom. This article describes the various possible explanations for the Dutch cases. The risk factors involved, have either a connection with imported BSE, local origin of BSE, or both. These factors can also be divided into introductory risk and propagation risk, terms that were also used in an EU risk assessment study. Research at ID-Lelystad since the early 1990s and at IKC-Ede has tried to assess the relative importance of the various risk factors, the results of which are discussed in this paper. The paper does not deal with the specifics of the cases diagnosed to date, because of the absence of an in-depth epidemiological investigation, but provides a general assessment of the risk factors that might have played a role. Important factors have been, in addition to the initial imports of cattle and meat and bone-meal from the UK, the continuing imports from other countries with covert BSE and the cross-contamination within the animal feed production lines. Emphasis is on the period of the early and mid-1990s, the period in which most calves with diagnosed BSE were born.     

Micronutrients affecting adipogenesis in beef cattle

Beef marbling is an important trait of meat quality and beef marbling influences the tenderness and flavor of beef, which contributes directly to the value of beef especially in the Japanese market. The lipid content of beef depends on the strain, sex, diet and fattening period of the animal. Japanese Black cattle (Wagyu) are well‐known for their ability to produce marbling beef and this is a popular strain in Japan. The development of beef marbling was closely associated with an increase in the number of adipocytes, that is, adipocyte differentiation in the skeletal muscle. This review article describes our experiment and related reports on micronutrients, especially vitamins and minerals, affecting adipogenesis in beef cattle. We pursue the possibility that manipulating the level of dietary micronutrients may become a new technique to promote beef marbling.     

Animal-derived feeds as possible vectors for bovine spongiform encephalopathy (BSE) in Germany. 1. Comparative risk assessment for a single animal food of animal origin

The occurrence of BSE cases in Germany after the ban of meat and bone meal for ruminant feed in 1994 requires a detailed investigation of animal derived feedstuffs regarding their specific risks as vectors for the disease. Accepting the theory that BSE is a prion transmitted disease, the theoretical infectious potential was calculated for animal derived feedstuffs. This calculation was based on the assumption, that risk material (brain, spinal cord) of one clinically diseased cattle was rendered in the process as established in Germany (133 degrees C, 3 bar, 20 min) or, alternatively, that one diseased animal was slaughtered resulting in normal processing of the by-products for human food production. From this risk assessment it became obvious that meat and bone meal was one, but probably not the most important source for the spreading of BSE. Taking into account the high sensitivity of calves it can be speculated that certain products, e.g. from bone processing (bone meal) and fat melting (mixed animal fats), commonly used for the formulation of milk replacers, might have been more important as pathways. As it can't be excluded retrospectively that infected meat and bone meal was imported from the UK, this non-calculable influence may have been related to the significance of the other products. The calculation model underlines that efficient removal of specified risk material (brain, spinal cord) and adequate processing (133 degrees C, 3 bar, 20 min) or alternatively other equivalent treatments of fats are prerequisites for minimising the risk of feed borne transmission of BSE by animal derived feedstuffs. The epidemiological consequences are part of a subsequent paper.     

我国肉牛生产现状及未来展望

肉牛产业是我国畜牧业和肉类生产的重要组成部分。中国牛肉产量位居世界第三,且随着中国经济的快速发展,牛肉消费随着人均国内生产总值的增加而增加,但中国国内的肉牛产业未能跟上消费增长,使中国成为其他国家牛肉的净进口国。此外,尽管需求不断增长,但产量几乎没有增长。近年来,牛肉生产增速放缓,导致牛肉价格大幅上涨。国内牛肉生产和消费受到肉牛库存不足的制约。中国肉牛产业面临着许多技术问题,包括传统养殖的转变、饲养和管理制度、牛品种的遗传改良等。中国肉牛产业的长期、可持续发展是中国面临的重要课题。     

Prediction of nitrogen excretion in feces and urine of beef cattle offered diets containing grass silage

Data from 286 beef cattle, obtained in total diet digestibility assessments, were used to examine effects of dietary and animal factors on N excretion in feces and urine and to develop prediction equations for N excretion in beef cattle. The animals used were mainly from beef breeds, at various ages (from growth to finishing) and live BW (153 to 580 kg), and offered diets containing grass silage at production feeding levels. Dietary forage proportion ranged from 199 to 1,000 g/kg of DM and dietary CP concentration from 108 to 217 g/kg of DM. Linear and multiple regression techniques were used to examine relationships between the efficiency of N utilization and dietary and animal variables with the experimental effects removed. The statistical analysis indicated that N excretion was related positively (P < 0.001) to live BW and intakes of DM, N, and ME, and negatively (P < 0.001) to dietary forage proportion. The prediction equation for N excretion, developed using N intake alone, produced a large r2 (0.898) and a small SE (12.3). Addition of live BW and forage proportion as supporting predictors to this relationship only marginally increased R2 to 0.915 and reduced SE to 11.2. Nitrogen excretion was less well related to live BW (r2 = 0.771, SE = 18.5) than to N intake. Addition of N intake as a proportion of DMI or ME intake to the relationship between live BW and N excretion increased R2 to 0.824 and reduced SE to 16.2. The internal validation of these equations revealed that using N intake as the primary predictor produced a very accurate prediction of N excretion. In situations where data on N intake are not available, prediction equations based on live BW and dietary N concentration together can produce a relatively accurate assessment of N excretion. A number of mitigation strategies to reduce N excretion in feces and urine in beef cattle are discussed, including manipulation of dietary N concentration, diet quality, and level of feeding. The prediction equations and mitigation strategies developed in the current study provide an approach for beef producers to quantify N excretion against production and to develop their own mitigation strategies to reduce N excretion.     

中国肉牛产业链分析及肉牛企业发展探讨

随着经济的快速发展,居民消费水平持续上升,我国的肉类消费结构正在逐渐升级,人们对牛肉的消费需求开始不断增加。然而,近年来国内牛肉的产量增幅不大,且供需缺口巨大,这为肉牛产业迎来了新的发展机遇。因此,中国肉牛企业应当瞄准市场需求,不仅能够弥补国内牛肉供应市场的短板,而且可为企业创造较高的经济效益。基于此,本文从肉牛产业链中的养殖业、食品加工业和牛肉消费市场3个层面对国内肉牛产业链现状和发展前景进行了分析,并结合企业自身的发展,探讨中国现代化、规模化、标准化的肉牛企业的发展方向。     

How the surveillance system may bias the results of analytical epidemiological studies on BSE: prevalence among dairy versus beef suckler cattle breeds in France

Until recently, epidemiological studies on Bovine Spongiform Encephalopathy (BSE) were based on Mandatory Reporting Systems (MRS) of clinically suspect bovines only, but rapid diagnostic tests were validated in 1999 and are used for targeted surveillance in Switzerland, France and other countries, as a complementary and secondary tool. Data on 30491 cattle issued from a French pilot program targeted at cattle having died on the farm, subjected to euthanasia or sent for emergency slaughter, did not show any significant difference in BSE risk between dairy and beef suckler breeds. The data also revealed that part of the clinical cases of BSE escaped the MRS, which permitted to detect more dairy than beef suckler affected cattle compared to the targeted surveillance in the same period (from August to December 2000) and region (Bretagne, Pays de la Loire and Basse Normandie regions). Analyzing together the data of the targeted surveillance and mandatory reporting system programs with a non-conditional logistic regression, we found that the odds of a dead cow being a BSE case among all dead cattle was 3.2 times higher for dairy breeds compared to beef suckler breeds. This confirmed British findings but points out to the fact that considering either MRS or targeted surveillance data alone may possibly create biases in epidemiological studies on BSE.     

Biosecurity practices of beef cow-calf producers

OBJECTIVE: To evaluate biosecurity practices of cow-calf producers. DESIGN: Cross-sectional survey. SAMPLE POPULATION: 2,713 cow-calf operations were used in phase 1 of the study, and 1,190 cow-calf operations were used in phase 2. PROCEDURE: Producers were contacted for a personal interview between Dec 30, 1996 and Feb 3, 1997 regarding their management practices. Noninstitutional operations with 1 or more beef cows were eligible to participate in the study. Producers who participated in the first phase of the study and who had > or = 5 beef cows were requested to continue in the study and were contacted by a veterinarian or animal health technician who administered further questionnaires. All contacts for the second phase of the study were made between Mar 3, 1997 and Apr 30, 1997. Additional data on use of various vaccines, testing of imported cattle for brucellosis, Mycobacterium paratuberculosis, bovine viral diarrhea, and tuberculosis as well as potential for feed contamination were collected during the second phase of the study. RESULTS: Producers commonly engaged in management practices that increased risk of introducing disease to their cattle such as importing cattle, failing to quarantine imported cattle, and communal grazing. Producers inconsistently adjusted for the increased risk of their management practices by increasing the types of vaccines given, increasing the quarantine time or proportion of imported animals quarantined, or increasing testing for various diseases in imported animals. CONCLUSIONS AND CLINICAL RELEVANCE: Cow-calf herds are at risk for disease exposure from outside sources when cattle are introduced to the herd, and producers do not always adjust management practices such as vaccination schedules and quarantine procedures appropriately to minimize this risk. Veterinary involvement in education of producers regarding biosecurity risks and development of rational and economical biosecurity plans is needed.     

A quantitative assessment of the risk of exposure to bovine spongiform encephalopathy via meat-and-bone meal in Japan

The feeding of meat-and-bone meal (MBM) derived from cattle infected with bovine spongiform encephalopathy (BSE) is a major source of BSE infection. The risks of BSE infection via MBM in Japan were examined quantitatively to estimate infectivity to cattle via MBM derived from a single clinically infected animal being rendered. Three routes of exposure were modeled: (i) feeding cattle concentrates containing MBM as an ingredient, (ii) feeding cattle concentrates contaminated with MBM from non-ruminant feed at feed plants and (iii) directly feeding MBM in supplemental form to cattle on farms. The effectiveness of measures designed to restrict the feeding of ruminants with ruminant MBM (feed restriction) as well as differences in the risk of exposure among regions were examined using the model.

The model revealed that the median total infectivity fed to dairy cattle via MBM derived from one infected animal was approximately 0.49 cattle oral ID₅₀ (5th percentile = 0.43 ID₅₀, 95th percentile = 0.54 ID₅₀). This value was reduced by 55% after the addition of MBM to cattle concentrates was restricted in 1996. The risk of exposure in dairy cattle was twice that in beef cattle. Comparisons of regional differences in exposure risk indicated that the risk was highest in a region where 14 of the 20 BSE cases reported to date were born. Our model suggested that the routes of exposure via MBM were unlikely to result in increased propagation of BSE in Japan. Furthermore, despite some regional variation, the risk of exposure declined further after the feed restriction was imposed in 1996.     

关于中国畜牧生产结构与肉牛经济的几个问题

中国畜产品生产指标1999年比1990年高出105.1个大师傅发点，人均高出87.1个百分点，而世界相应指灵敏仅分别高出17.4和3.4个百分点。中国畜牧业产值占大农业总产值已达30%，显示整个畜牧业的高速增长，肉牛生产是畜牧业中的重要组成部分，发展迅速，牛肉总产量占全国总产肉量比例由1982年的1%增长到8.43%，超过了500万t，中国畜种组成中猪，鸡比例大高，在生产结构战略调整中应大力发展养牛业，肉牛数量占总牛头数90%，80%的肉牛分布在农区，中国农区肉牛业将是不同于北美精料型，澳洲草原型的第三种类型，有自己的特点，二十年来，中国牛肉产量年递增率平均达9.1%-24.97%，而世界同期仅为1.02%。按中国情况，2005年，牛肉总产将达到650万t，可超过世界第二大牛肉生产国的巴西；而到2016年，中国牛肉总产可望达1000万t。中国牛肉的基本市场仍在国内，发展肉牛仍是广大农民增收的一个门类。     

Review on the epidemiology and dynamics of BSE epidemics

The paper describes how the comprehensive surveillance of bovine spongiform encephalopathy (BSE) and studies carried out on these data has enhanced our knowledge of the epidemiology of BSE. Around 7, 000 BSE cases were detected through the screening of about 50 million cattle with rapid tests in Europe. It confirmed that the clinical surveillance had a poor capacity to detect cases, and also showed the discrepancy of this passive surveillance efficiency between regions and production types (dairy/beef). Other risk factors for BSE were being in a dairy herd (three times more than beef), having a young age at first calving (for dairy cattle), being autumn-born (dairy and beef), and being in a herd with a very high milk yield. These findings focus the risk on the feeding regimen of calves/heifers. Several epidemiological studies across countries suggest that the feedborne source related to meat and bone meal (MBM) is the only substantiated route of infection - even after the feed ban -, while it is not possible to exclude maternal transmission or milk replacers as a source of some infections. In most European countries, the average age of the cases is increasing over time and the prevalence decreasing, which reflects the effectiveness of control measures. Consistent results on the trend of the epidemic were obtained using back-calculation modelling, the R(0) approach and Age-Period-Cohort models. Furthermore, active surveillance also resulted in the finding of atypical cases. These are distinct from previously found BSE and classified in two different forms based on biochemical characteristics; their prevalence is very low (36 cases up to 1st September 2007), affected animals were old and some of them displayed clinical signs. The origin and possibility of natural transmission is unknown.     

西门塔尔与蒙古牛育成母牛屠宰对比试验报告

[目的]为了进一步说明肉牛杂交改良效果和经济效益。[方法]对西门塔尔（西门塔尔牛×蒙古牛杂交F2代）与蒙古牛育成母牛进行了本次屠宰对比试验。[结果]宰前活重、屠体重、净肉重的P值分别为0.000、0.000和0.001,两组差异极显著（P〈0.01）。[结论]西门塔尔育成母牛较蒙古牛育成母牛产肉性能提高较大,而近一段时间牛肉肉价一直处于较高的水平,改良牛会产生更高,更明显的收益。     

肉牛冷冻胚胎洲际引种试验

从加拿大分两批引进夏洛来和西门塔尔良种肉牛胚胎共３４枚,解冻后我国荷斯坦受体母牛,“借腹怀胎”生产人用种牛后代,以代替引进活牛。将进口保存液和自制保存液对移植妊娠率的影响进行比较,结果进口保存液（５３．３％）优于自制保顾液（２１．２％）,将不同营养状况受体牛对移植妊娠率的影响比较,结果营养良好埂优于营养较差乾;将进口冷冻胚胎“借腹怀胎”生产肉用 牛与直接进口活种牛的成本进行比较,结果前者显著低于后     

Meat and potential risks

By the term "meat" the consumer understands muscle meat, that is skeletal muscle. The german regulations, the "Leits?tze für Fleisch und Fleischerzeugnisse" as well as the Codex Alimentarius define meat in a much broader sense to include all edible parts of slaughtered or shot warm-blooded animals (skeletal muscles, fat, heart, gut, liver etc). Therefore, a differentiated procedure is required when the risk of BSE transmission by meat has to be estimated. This must be based on knowledge of occurrence, amount, and persistence of BSE agents in the organs of animals. The risk evaluation has to include further factors: differences between animal species, age of the animal at the time of slaughter, the possibility of contamination during the slaughtering and cutting process, and--as far as meat products are concerned--the processing technology. To date there are no indications for the existence of transmissible spongiform encephalopathy in pigs, poultry and fish, even though BSE has been transmitted to pigs experimentally by intracranial administration. Muscle meat of these species can be considered safe. Muscle meat of experimentally infected cattle in the preclinical stage and even of animals with clinically manifest BSE has not shown infectivity in homologous and autologous bioassays performed so far. This finding justifies the assumption that the risk of BSE exposure by the consumption of beef can be classified as extremely low. Nevertheless, the absence of a proof of infectivity can at present not be equated with absence of BSE agents. This is because of the limits of sensitivity of the bioassays and because muscle meat does contain non-muscle tissue such as connective tissue collagen, nerve and lymph tissue and blood vessels.