British Cattle Research Articles

Estimating risk over time using data from targeted surveillance systems: Application to bovine tuberculosis in Great Britain

For infections that are typically asymptomatic, targeted surveillance systems (whereby individuals at increased risk are tested more frequently) will detect infections earlier on average than systems with random testing or in systems where all individuals are tested at the same intervals. However, estimating temporal trends in infection risk using data from such targeted surveillance systems can be challenging. This is similarly a problem for targeted surveillance to detect faults of individual industrial components. The incidence of bovine tuberculosis (TB) in British cattle has been generally increasing in the last thirty years. Cattle herds are routinely tested for evidence of exposure to the aetiological bacteria Mycobacterium bovis, in a targeted surveillance programme in which the testing interval is determined by past local TB incidence and local veterinary discretion. The UK Department for Environment, Food and Rural Affairs (Defra) report the monthly percentage of tests on officially TB-free (OTF) herds resulting in a confirmed positive test for M. bovis (i.e. the percentage of tested herds with OTF status withdrawn), which contains substantial fluctuations (three years apart) within the increasing trend. As the number of herds tested changes over time, this cyclic trend is difficult to interpret. Here we evaluate an alternative to the Defra method in which we distribute each incident event across the period at risk to infer the underlying trends in infection incidence using a stochastic model of cattle herd incidence and testing frequencies fitted to data on the monthly number of herds tested and number of these with OTF status withdrawn in 2003–2010. We show that for an increasing underlying incidence trend, the current Defra approach can produce artefactual fluctuations whereas the alternative method described provides more accurate descriptions of the underlying risks over time.

Effects of changes in external production conditions on economic values of traits in Continental and British beef cattle breeds

Future production conditions for beef cattle may become increasingly extensive due to human population growth, climate change and competition for resources, which may limit the amount of concentrates available for beef production. Therefore, the effect of more extensive production conditions on economic values (EV) in beef cattle breeding goals was investigated. Using a deterministic bio-economic model, two alternative production conditions were analysed in two breed groups (Continental and British): (1) entirely roughage-based (RB) and (2) minimum use of concentrates (MC). Three harvested roughage qualities (early, medium and late cut) were included in both scenarios, resulting in a total of 12 situations. Performance of bulls, surplus heifers and replacement heifers was assumed to vary considerably between the situations, while the performance of suckler cows was assumed to be constant. EV were estimated for seven functional traits: herd life of cow (HL), age at first calving, calving interval, stillbirth (S), twinning rate (T), calving difficulty, limb and claw disorders (LC), and for seven production traits: birth weight (BW), carcass weight (CW), carcass conformation, carcass fat, growth rate from birth to 200 days (weaning), growth rate from 200 to 365 days and growth rate from 365 days to slaughter. HL was the economically most important trait followed by CW in all situations, while S, T, LC and BW were of little economic importance. Little re-ranking for the traits was found between situations. The functional traits were more important than or equally important to the production traits for early cut roughage, but had decreasing importance as roughage quality was reduced, and vice versa for the production traits. Even so, functional traits were of higher economic importance for the Continental breed group compared to the British breed group. Small differences between the EV estimated for the RB and MC situations were observed. A sensitivity analysis for roughage price showed increased importance of production traits following an increased roughage price. Substitution of subsidies with settling prices that covers production costs in the profit equation led to increased importance of carcass weight, age at first calving and calcing interval while the importance of herd life of cow was reduced. Overall, the results suggest that changed external productions conditions have minor to moderate effects on future breeding objectives for beef cattle.

Effect of nutritional regimen including limit feeding and breed on growth performance, carcass characteristics and meat quality in beef cattle

McGregor, E M., Campbell, C. P., Miller, S. P., Purslow, P. P. and Mandell, I. B. 2012. Effect of nutritional regimen including limit feeding and breed on growth performance, carcass characteristics and meat quality in beef cattle. Can. J. Anim. Sci. 92: 327–341. The effects of nutritional management regimen and breed on growth performance, carcass attributes, and meat quality were evaluated in 68 British (BRIT) and Continental (CONT) crossbred steers, managed on one of three nutritional regimens: (1) ad libitum access to a 77% corn diet (ALGRAIN), (2) limit feeding initially of the 77% corn diet, followed by ad libitum access to the 77% corn diet (LFGRAIN), and (3) limit feeding initially of a 90% haylage diet, followed by ad libitum access to the 77% corn diet (LFHAYL). Nutritional regimen by breed interactions (P<0.02) were present for average daily gain, dry matter intake (DMI), gain to feed, and shear force. LFHAYL regimen decreased gains to a greater extent for BRIT steers than CONT steers managed on ALGRAIN or LFGRAIN. Feed intakes were similar across nutritional regimens for CONT steers, while DMI was depressed in BRIT on LFHAYL as compared with steers started on ALGRAIN or LFGRAIN. Gain to feed was greater in BRIT cattle on LFGRAIN vs. ALGRAIN, while gain to feed was similar in CONT started on grain (ALGRAIN, LFGRAIN). Shear force was lower for beef from LFHAYL BRIT vs. beef from BRIT on ALGRAIN or LFGRAIN, while the converse was true for CONT. Limit feeding of a high-energy diet may be appropriate for cattle of British background to reduce feed input costs, while ensuring tenderness.

Ten‐minute chat

Former practitioner Andrew Praill is president of the British Cattle Veterinary Association and a member of the BVA Board.

Comparing Badger (Meles meles) Management Strategies for Reducing Tuberculosis Incidence in Cattle

Bovine tuberculosis (bTB), caused by Mycobacterium bovis, continues to be a serious economic problem for the British cattle industry. The Eurasian badger (Meles meles) is partly responsible for maintenance of the disease and its transmission to cattle. Previous attempts to manage the disease by culling badgers have been hampered by social perturbation, which in some situations is associated with increases in the cattle herd incidence of bTB. Following the licensing of an injectable vaccine, we consider the relative merits of management strategies to reduce bTB in badgers, and thereby reduce cattle herd incidence. We used an established simulation model of the badger-cattle-TB system and investigated four proposed strategies: business as usual with no badger management, large-scale proactive badger culling, badger vaccination, and culling with a ring of vaccination around it. For ease of comparison with empirical data, model treatments were applied over 150 km2 and were evaluated over the whole of a 300 km2 area, comprising the core treatment area and a ring of approximately 2 km. The effects of treatment were evaluated over a 10-year period comprising treatment for five years and the subsequent five year period without treatment. Against a background of existing disease control measures, where 144 cattle herd incidents might be expected over 10 years, badger culling prevented 26 cattle herd incidents while vaccination prevented 16. Culling in the core 150 km2 plus vaccination in a ring around it prevented about 40 cattle herd breakdowns by partly mitigating the negative effects of culling, although this approach clearly required greater effort. While model outcomes were robust to uncertainty in parameter estimates, the outcomes of culling were sensitive to low rates of land access for culling, low culling efficacy, and the early cessation of a culling strategy, all of which were likely to lead to an overall increase in cattle disease.

Simulating the impact of badger culling on bovine tuberculosis in cattle

IT is now 15 years since the Krebs report on bovine tuberculosis (TB) in cattle and badgers highlighted the need for a rigorous scientific trial to quantify the role of...

Emerging skin conditions in cattle

There are various common skin conditions seen in British cattle which practioners are able to diagnose and treat; however, there are emerging and other conditions that they may have little...

When Contexts Meet

The article discusses three versions of context. First, UK Government legislation, the British Cattle Tracing System (CTS), as a context that frames and guides good farming practices to promote accountability for cattle movements and to control disease. It describes how the legislative context creates particular constructions of farmers, cows, and good and bad farming practices. Second, the article creates context as the local farm-based practices of cattle movement and monitoring. Differences and similarities between the legislative requirements and the farm-based practices are discussed. The farming practices are primarily practices of responsibility and care that are embodied, relational, collective, and responsive. The article draws upon feminist insights into responsibility and accountability that accountability is mundane practices of touch, regard, looking back, and becoming with. Thereby, the article creates a third context in which local farming practices, legislation, and feminism meet and interact with one another. Within this “meta-context” of interferences between contexts, accountability is revisioned as the very condition of farm-based practices of care and responsibility. At the same time, the article revisions context as emergent in interferences and enacts alternative versions of farmers, cows, and good and bad practices.

Localized reactive badger culling increases risk of bovine tuberculosis in nearby cattle herds

Human and livestock diseases can be difficult to control where infection persists in wildlife populations. Control of bovine tuberculosis (bTB) in British cattle is complicated by the maintenance of Mycobacterium bovis (the causative agent of bTB) in badgers, acting as reservoirs of infection. Although over 20 000 badgers were culled to control bTB between 1975 and 1997, the incidence of bTB in cattle has substantially increased in parts of Great Britain in recent decades. Our case-control study, involving 1208 cattle herds, provides further evidence of the detrimental effect of localized reactive badger culling in response to the disclosure of a confirmed bTB herd breakdown in cattle. The presence of any reactive badger culling activity and increased numbers of badgers culled in the vicinity of a herd were associated with significantly increased bTB risk, even after adjusting for other important local risk factors. Such findings may partly explain why some earlier localized approaches to bTB control were ineffective.

A Preliminary Study of Genetic Factors That Influence Susceptibility to Bovine Tuberculosis in the British Cattle Herd

Associations between specific host genes and susceptibility to Mycobacterial infections such as tuberculosis have been reported in several species. Bovine tuberculosis (bTB) impacts greatly the UK cattle industry, yet genetic predispositions have yet to be identified. We therefore used a candidate gene approach to study 384 cattle of which 160 had reacted positively to an antigenic skin test (‘reactors’). Our approach was unusual in that it used microsatellite markers, embraced high breed diversity and focused particularly on detecting genes showing heterozygote advantage, a mode of action often overlooked in SNP-based studies. A panel of neutral markers was used to control for population substructure and using a general linear model-based approach we were also able to control for age. We found that substructure was surprisingly weak and identified two genomic regions that were strongly associated with reactor status, identified by markers INRA111 and BMS2753. In general the strength of association detected tended to vary depending on whether age was included in the model. At INRA111 a single genotype appears strongly protective with an overall odds ratio of 2.2, the effect being consistent across nine diverse breeds. Our results suggest that breeding strategies could be devised that would appreciably increase genetic resistance of cattle to bTB (strictly, reduce the frequency of incidence of reactors) with implications for the current debate concerning badger-culling.

Considering risk assessment up close: The case of bovine spongiform encephalopathy

Risk assessment studies often adopt a quantitative approach and analyse decisions or judgements in relation to risk at one specific point in time. These studies certainly have their merits but their preponderance in the literature on risk has been to the exclusion of qualitative studies that seek to examine judgements of subjects over an extended period of time. I seek to redress this imbalance by examining how scientists assessed risk in the context of a significant public health problem in the UK: the emergence of bovine spongiform encephalopathy (BSE) in cattle. This disease first emerged in British cattle in 1986. Yet over 20 years on, its implications for human health are still being assessed by scientists. In this paper, I examine the reasoning strategies that scientists employed to make risk assessments in relation to BSE in the period between 1986 and 1996. Two arguments in particular (analogical argument and the argument from ignorance) were the mainstay of scientific reasoning in the period under investigation. The rational standing of these arguments varied over time in relation to evidence that was emerging from experimental and other studies. It is argued that it is not possible to capture the factors which are necessary to understanding scientific risk assessments in relation to BSE within the type of quantitative, static study that is typically pursued within research on risk.

Local Cattle and Badger Populations Affect the Risk of Confirmed Tuberculosis in British Cattle Herds

BackgroundThe control of bovine tuberculosis (bTB) remains a priority on the public health agenda in Great Britain, after launching in 1998 the Randomised Badger Culling Trial (RBCT) to evaluate the effectiveness of badger (Meles meles) culling as a control strategy. Our study complements previous analyses of the RBCT data (focusing on treatment effects) by presenting analyses of herd-level risks factors associated with the probability of a confirmed bTB breakdown in herds within each treatment: repeated widespread proactive culling, localized reactive culling and no culling (survey-only).Methodology/Principal FindingsNew cases of bTB breakdowns were monitored inside the RBCT areas from the end of the first proactive badger cull to one year after the last proactive cull. The risk of a herd bTB breakdown was modeled using logistic regression and proportional hazard models adjusting for local farm-level risk factors. Inside survey-only and reactive areas, increased numbers of active badger setts and cattle herds within 1500 m of a farm were associated with an increased bTB risk. Inside proactive areas, the number of M. bovis positive badgers initially culled within 1500 m of a farm was the strongest predictor of the risk of a confirmed bTB breakdown.Conclusions/SignificanceThe use of herd-based models provide insights into how local cattle and badger populations affect the bTB breakdown risks of individual cattle herds in the absence of and in the presence of badger culling. These measures of local bTB risks could be integrated into a risk-based herd testing programme to improve the targeting of interventions aimed at reducing the risks of bTB transmission.

Gene flow in a national cross-breeding beef population

Future progress in genetic improvement and the monitoring of genetic resources in beef cattle requires a detailed understanding of the population under selection. This study examines the gene flow in the UK beef population with an uncommon breeding structure involving interaction between the beef and dairy populations. British Cattle Movement Service records were used as the primary source of information, and these data were triangulated with UK government statistics, other industry information sources and existing literature to build up a profile of the UK beef industry. Estimates were made of the breed composition of suckler cows, breeding bulls and the prime slaughter population. Cross-bred animals made up 85% and 94%, respectively, of the commercial beef breeding cow and prime slaughter populations. Holstein/Friesian (through cross-breeding) made up the largest proportion of genes in both these populations with 33% and 28%, respectively. The next five most popular breeds were specialist beef breeds: Limousin (22% and 18%), Charolais (11% and 6%), Simmental (9% and 11%), Angus (7% and 8%) and Belgian Blue (6% and 6%). Combined, the top seven beef breeds accounted for 94% of beef genetics in the prime slaughter population, and 80% of this came from non-native breeds. The influence of dairy breeds in the commercial beef breeding population was highlighted by the fact that 44% of replacement commercial beef breeding females were sourced from beef-sired crosses in the dairy herd, and in total 74% of all maternal grand dams of prime slaughter animals were Holstein/Friesian. The use of selection index technology was also investigated by analysing breeding bull sale results, with the correlation between the terminal sire index and sale price of young breeding bulls being generally moderate but significant, ranging from 0.21 to 0.38 across the major beef breeds. The most influential source of genetics in the commercial suckler beef herd was natural service breeding bulls. These were mostly sourced from pedigree breeders, and accounted for 47.8% of the genetics in the prime beef population. Artificial insemination sires were responsible for 16.6% of prime beef genetics, with the remaining 35.6% coming from dairy breeds, 95% of which was Holstein/Friesian.

Ten‐minute chat

Andy Biggs is a cattle practitioner at Vale Veterinary Centre in Devon. He is an international mastitis consultant and has been president of the Western Counties Veterinary Association and the British Cattle Veterinary Association.

Origins and genetic diversity of New World Creole cattle: inferences from mitochondrial and Y chromosome polymorphisms

The ancestry of New World cattle was investigated through the analysis of mitochondrial and Y chromosome variation in Creoles from Argentina, Brazil, Mexico, Paraguay and the United States of America. Breeds that influenced the Creoles, such as Iberian native, British and Zebu, were also studied. Creoles showed high mtDNA diversity (H = 0.984 +/- 0.003) with a total of 78 haplotypes, and the European T3 matriline was the most common (72.1%). The African T1a haplogroup was detected (14.6%), as well as the ancestral African-derived AA matriline (11.9%), which was absent in the Iberian breeds. Genetic proximity among Creoles, Iberian and Atlantic Islands breeds was inferred through their sharing of mtDNA haplotypes. Y-haplotype diversity in Creoles was high (H = 0.779 +/- 0.019), with several Y1, Y2 and Y3 haplotypes represented. Iberian patrilines in Creoles were more difficult to infer and were reflected by the presence of H3Y1 and H6Y2. Y-haplotypes confirmed crossbreeding with British cattle, mainly of Hereford with Pampa Chaqueño and Texas Longhorn. Male-mediated Bos indicus introgression into Creoles was found in all populations, except Argentino1 (herd book registered) and Pampa Chaqueño. The detection of the distinct H22Y3 patriline with the INRA189-90 allele in Caracú suggests introduction of bulls directly from West Africa. Further studies of Spanish and African breeds are necessary to elucidate the origins of Creole cattle, and determine the exact source of their African lineages.

Global geographies of innovation diffusion: the case of the Australian cattle industry

The geographies and histories of the introduction of cattle breeds to Australia in the period since white settlement are documented as an example of the diffusion of agricultural innovations. Three phases of development are identified: a colonial expansion phase from the late eighteenth to the early twentieth century during which a number of primarily British cattle breeds were imported by the colonial settlers; an innovative phase in the mid twentieth century when both governments and private interests sought to produce or import new breeds deemed to be better adapted to Australian environments; and a multifunctional phase in recent decades. In this final phase, government deregulation and new technologies, such as the long distance transport of genetic packages, have facilitated the importation and development of many new cattle breeds in Australia. While this has produced a significant rise in the total number of breeds represented nationally, many recent and historic breeds currently exhibit extremely small numbers and a few generally well‐established breeds such as Holstein, Hereford and Angus still dominate the national herd. This study of changing breed types and introductions provides some evidence of post‐productivism and of a multifunctional transition in that several cattle breeds favoured by hobby farmers and boutique breeders are now represented, but the aggregate numbers for these breeds remain small and the numbers for several of the traditional (or colonial) breeds are currently in decline. Overall, it is apparent that Australia's cattle industry retains a strongly productivist ethos and that, particularly given the country's very great environmental variation, its levels of breed diversity remain low.

Postal survey of contacts between cattle farms on the Isle of Lewis

The British Cattle Movement Service (BCMS) database contains an unprecedented quantity of data on the movement of cattle within the UK. These data may be used to construct models of...

Big issues on the agenda at the BCVA congress

Climate change, cost and responsibility sharing, vectorborne disease, dairy cow welfare and bovine TB were all discussed at the British Cattle Veterinary Association (BCVA) congress, held in Southport from November 26 to 28, 2009. Suzanne Jarvis reports.

Herd and individual animal risks associated with bovine tuberculosis skin test positivity in cattle in herds in south west England

The aim of this study was to investigate the cattle—exposure factors associated with the risk of a bovine animal reacting to a bovine tuberculosis (bTB) skin test at a whole herd test. There were 148 study farms enrolled. These were located in six counties of the south west of England in an area considered endemic for bovine tuberculosis (bTB): 24% were restocked after foot and mouth disease (FMD) in 2001; all farms were located within the Randomised Badger Culling Trial (RBCT) area. Data on cattle on these farms were sourced from the bTB Vetnet database from 1996 to 2004 and from the British Cattle Movement Scheme database. Individual animal records were created that included data on whether or not an animal became a reactor at a full-herd bTB test between 1 June 2001 and 19 August 2004, their prior exposure to cattle with bTB (defined by presence at a bTB test where at least one reactor was detected), whether the animal was homebred, the farm history of bTB and the farm restocking status. Data from 144 farms were used, 4 farms had no data.Cattle were more likely to react to the bTB skin test when they had been present at a previous bTB herd test (or tests) where other cattle had reacted to the skin test. This positively correlated with age and the number of bTB tests an animal had had. Cattle on restocked farms were less likely to react to the skin test compared with cattle on continuously stocked farms. These results highlight the likely importance of exposure to infected cattle at a previous test as a source of infection to cattle that subsequently became reactors and suggest that there was a lower risk of exposure to bTB to cattle in newly formed herds.

Congenital tremor and hypomyelination associated with bovine viral diarrhoea virus in 23 British cattle herds

This paper presents data from 23 British herds investigated between 1991 and 2007 where neurological disease in calves was caused by bovine viral diarrhoea virus (BVDV) infection. A variety of...