BACKGROUND
livestock identification and tracing legislation
the movement of animals within the united kingdom  is vital to the economics of the livestock industry, but carries with it the risk of transmitting infectious diseases across substantial geographic distances  <cit> .
over the last sixty years, the uk government has introduced increasingly detailed legislation relating to the identification and tracing of cattle.
a requirement to identify cattle was first introduced in  <dig>  as part of the effort to eradicate bovine tuberculosis .
in  <dig>  the movement of animals  order  <dig>  required farmers to keep a record of all movements of bovines on or off their premises, and to store these records for three years  <cit> .
in  <dig>  in response to concerns over bovine spongiform encephalopathy , tighter controls were introduced.
the bovine animals  order  <dig> required farmers to record the births of all calves and the identity of their dam, and to keep those records for ten years.
dairy cattle were required to be marked and recorded within  <dig> hours of birth, and other cattle within  <dig> days.
the movement of animals  amendment order  <dig> extended the period for which movement records had to be kept to  <dig> years.
the european economic community issued council directive 92/102/eec in  <dig>  which required  movements of cattle to be recorded including origin and destination of the cattle concerned; cattle also had to be identified with an ear tag bearing a code of no more than  <dig> characters.
in the uk, this was implemented by the bovine animals  order  <dig>  that order also required cattle farmers to register their holding with their local animal health office, and introduced the ear tag allocation system to ensure that every bovine animal had a unique identity.
in  <dig>  the ministry of agriculture, fisheries, and food  considered that implementing a computerised cattle traceability system  was necessary to enable the lifting of the export ban on british beef  <cit> .
accordingly, the cts was established in september  <dig>  during the autumn of  <dig>  the "cattle count 2000" exercise was carried out, to register cattle born or imported before the first of july  <dig> , and to confirm the location of cattle born between then and the twenty-seventh of september  <dig> .
cattle passports issued since  <dig> september  <dig> take the form of chequebook-style passports .
these consist of: a front page with details of the animal's eartag, breed, date of birth, and genetic dam, as well as the passport's issue  date; a short summary of previous holdings the animal has been on prior to the passport being issued; movement summary pages into which details of movements of the animal are entered; detachable movement cards by which movements may be reported to the cts; and a back cover for reporting the animal's death.
as of january  <dig>  it has been a legal requirement to report all movements of bovine animals to the cts.
the british cattle movement service  is responsible for running the cts.
the rapid analysis and detection of animal-related risks project  was started in  <dig> by the department for environment food and rural affairs  to collect veterinary surveillance data from different sources in the uk.
it is being developed and released in phases between  <dig> and  <dig>  phase  <dig> took place in march  <dig>  and contained information on the uk cattle population as well as data on salmonella cases.
the cattle movement data contained within radar are supplied by the bcms  <cit> .
cattle movements are reported to the bcms by the holdings at both ends of the movement: i.e.
an "off" record is created at one holding, and an "on" record at the other.
part of radar phase  <dig> has been to turn unpaired movements into a life history for each animal.
first, duplicate movement records are discarded, as are movements before the birth date, or after the death date .
a record of the animal's life history is then generated, consisting of a series of stays at locations , as can best be described by the extant movement records  <cit> .
these movement data have been used as the basis for a broad range of epidemiological models  <cit> , as well as a smaller body of work on the demographics of the uk cattle industry  <cit> .
movement control legislation
movements of bovines since  <dig> have not occurred in an unchanging regulatory environment.
there have been movement restrictions in the face of specific disease outbreaks: nationwide during the  <dig> foot and mouth disease epidemic and more locally during the smaller  <dig> epidemic; and from september  <dig> onwards to tackle bluetongue.
additionally, regulations have been introduced to try and make the uk cattle herd less susceptible to disease transmission.
a six-day standstill period was introduced on  <dig> august  <dig> by the disease control  order 2003; this meant that if any sheep, goats, cattle or pigs were moved onto a farm, then no sheep, goats, or cattle could be moved off that farm for  <dig> days.
as an attempt to control the spread of btb, pre-movement testing of bovines was introduced in a phased manner by the tuberculosis  order  <dig>  the tuberculosis  order  <dig>  the tuberculosis  order  <dig>  and the tuberculosis  order  <dig>  bovines on a farm with a 1- or 2-year btb testing interval in england and wales being moved must have been tested for btb within  <dig> days.
in scotland, animals must additionally be tested 60- <dig> days post-movement.
previous work
some other previous work on related questions based on radar data has been published.
defra's farming statistics team have published several "cattle books" containing descriptive statistics on the size, location, breed make-up, and so on of the uk cattle herd.
the most recent of these described the cattle herd in  <dig>  with population statistics such as number and ages of cattle, their breeds and geographic distribution captured as at  <dig> june  <dig>   <cit> .
statistical analyses of bcms movement data have highlighted biases in the reporting of birth dates  <cit> , and the fact that certain classes of movements  are under-reported  <cit> .
two seasonal peaks in movement volume are observed in the spring and autumn, and most movements of livestock occur during the working week, with a peak on wednesdays  <cit> .
while most animals only move a short distance, there are a small number of animals that move much further.
mitchell and colleagues described the mean distance moved as  <dig> km, and the maximum as  <dig> km  <cit> , while christley and colleagues considered february  <dig>  and found the median movement distance to be  <dig> km, and the maximum  <dig> km  <cit> .
the requirement to record the birth, death, and movements of cattle exists across the eu; various member states' data have been employed by researchers interested in agricultural economics or epidemiology.
for example, in  <dig>  most cattle moved within portugal were young beef stock, and most of the cattle were found in the north of the country; movements in the south of the country were less frequent, but tended to be substantially larger  <cit> .
natale and colleagues constructed a static network model of the italian cattle herd based on movements recorded in  <dig>  as well as considering the types of holdings that participated in movements, and the distances of movements.
they used disease simulation to suggest that targetting movement restrictions to affect central  farms could be a useful disease control tool in the event of an outbreak  <cit> .
in sweden, nöremark and colleagues have considered data on cattle and pigs together; similarly to the uk, they found peaks in cattle movements in the spring and autumn, reporting bias in dates, and that most movements of cattle and pigs occurred over a relatively short distance, with a few much longer movements  <cit> ; they went on to perform network analyses of these movement data, and considered the types of holding that were of greatest epidemiological significance within the network  <cit> .
this article
in this article, radar data for the past decade are used to illustrate the demographics of uk cattle, and to consider trends in movement patterns across that decade.
this long-term approach is in contrast to previous authors who have typically concentrated on a single year, or a few years at most.
the distribution of number of movements, their timings, and the types of holding involved in movement cattle are analysed, as well as the number of cattle in the uk, and the ages and locations at which they die.
since livestock movements are important for the spread of infectious diseases, the frequency and distance cattle move are analysed, as well as how frequently contacts between farms recur.
RESULTS
movement numbers, timing, and holding types
the extract from radar supplied by defra contained movements of bovines in the uk up to  <dig> april  <dig>  the radar livestock movements table contains  <dig> , <dig> records, representing the movements of  <dig> , <dig> distinct animals between  <dig>  distinct locations.
the number of movements in each month of  <dig> to  <dig> is plotted in figure  <dig>  the large spike in the autumn of  <dig> is an artifact of cattle count  <dig>  when previously unregistered cattle were registered, and movements from their birth locations to their then-current ones inferred.
the quality of pre- <dig> movement data remains questionable, however.
the number of movements beginning and leaving premises of different types in  <dig> and  <dig> is shown in table 1; note that births and deaths  will not appear in these figures.
"count" indicates the number of holdings of that type.
the first column contains the source holding type.
holding type abbreviations are defined in table  <dig>
italic numbers show where the observed number was greater than the expected number, bold numbers show where the observed number was less than the expected number, and numbers in normal type show where the observed number was within  <dig> movement of the expected number the first column contains the source holding type.
holding type abbreviations are defined in table  <dig>
livestock numbers and ages
radar contains data on  <dig> , <dig> animals , of which  <dig> , <dig> have a birth date but no death date, giving an upper bound on the number of cattle alive in the uk at the time the data were provided.
the ages at which cattle die are shown in figure 2; the peaks are at  <dig> days, around  <dig> months, around  <dig> months, and around  <dig> months.
table  <dig> shows the number of animals that died on each holding type; 99% of deaths occur on animal holdings or at red meat slaughterhouses.
figures  <dig> and  <dig> show the ages at which cattle die on red meat slaughterhouses and animal holdings, respectively.
frequency and distance of movements
the distribution of number of times an animal moves in its life is shown in figure  <dig>  the x-axis has been truncated at 15; the largest number of moves in a lifetime according to radar is  <dig>  the distributions are shown for all cattle, as well as beef and dairy cattle.
the distribution of distances animals move in their life is shown, using a log scale, in figure  <dig>  again subdivided into beef and dairy cattle.
the x-axis has been truncated at  <dig>  km; the greatest distance moved in the life of a single animal according to radar is  <dig>  km.
the relationship between the number of times an animal moved in its life and the total distance it moved in its life is examined in figure 7; coloured hexagonal binning has been used to illustrate the density of animals across the figure  <cit> .
spearman's rank correlation coefficient ρ =  <dig> , p <  <dig>  × 10- <dig>  showing a weak but statistically significant correlation between distance moved in life and number of movements in life.
the distribution of length of time animals spend on a particular holding is shown in figure  <dig>  the x-axis is truncated at  <dig> days , and the y-axis is logarithmic; the longest stay of an animal on a location according to radar was  <dig> days .
the peaks are at around  <dig> months, and around  <dig> months.
changes in movement patterns over the past decade
the distances of movements across the years 1999- <dig> are shown in figure 10; the box and whisker plots show the median and interquartiles  and the central ninety-five percentiles , whilst the blue line indicates the mean.
the change in movement batch sizes across the same time period is shown in figure  <dig>  the in- and out-degrees of farms taking a single static network for each year are shown in figure  <dig>  the number of cattle moved onto and off farms in a year is shown in figure  <dig>
discussion
movement numbers, timing, and holding types
the foot and mouth disease epidemics in  <dig> and  <dig> are both noticeable as a drop in movement volume in figure  <dig>  even at the height of the  <dig> epidemic, however, there was still a certain amount of movement going on; licenses were granted for movements within the infected area, from the uninfected area to the infected area, and within the uninfected area.
as would be expected, the vast majority of movements involve agricultural holdings, markets, and slaughterhouses.
table  <dig> shows that agricultural holdings are net exporters of animals, the numbers of animals entering and leaving markets are roughly the same, and that slaughterhouses are net importers of animals.
since animals are born on farms, pass through markets, and die at slaughterhouses, these figures are reassuringly predictable.
comparing tables  <dig> and  <dig> shows that there were substantially fewer movements between animal holdings in 2008- <dig> than would be expected by chance; the majority of this difference is explained by the greater number of movements from animal holdings to markets and slaughterhouses, and from markets to animal holdings.
similarly, there is very little movement of animals from market to market, animals instead moving to or from animal holdings.
as well as being an interesting insight into the structure of the cattle industry in the uk, these figures would be valuable for constructing an economic model of livestock movements, which in turn might be a useful technique for predicting future patterns of livestock movement in the uk.
livestock numbers and ages
figures  <dig>   <dig>  and  <dig>  and table  <dig> provide some insight into the mortality of british cattle.
table  <dig> shows unremarkably that the majority of cattle deaths occur at red meat slaughterhouses; also that animal holdings and red meat slaughterhouses account for nearly all  cattle deaths between them.
in the light of concerns about the risk bse posed to human health, the fresh meat  regulations  <dig> were introduced on  <dig> march  <dig>  they banned cattle that were over thirty months old from entering the human food chain; instead the animals were slaughtered, and farmers paid compensation under the over thirty months slaughter scheme.
this ban was relaxed on  <dig> november  <dig>  when older cattle were again eligible to enter the human food chain, provided they tested negative for bse.
the effect of this so-called "over thirty month rule"  is clear to see in figures  <dig> and  <dig> -- there is a substantial spike in the number of cattle dying at thirty months old.
figure  <dig> shows the distribution of ages of animals dying at red meat slaughterhouses.
there is a substantial peak at around a week of age, particularly among dairy cattle; male dairy calves are worth very little, so some are slaughtered at a young age to save the cost of rearing them; rennet may also be extracted from the abomasums of calves.
animals are typically slaughtered for veal at around  <dig> months of age; it is clear from figure  <dig> that this remains a insignificant beef product in the uk.
intensively reared beef is produced from beef and dairy animals of around  <dig> months of age; these animals are fed cereals and concentrates and so come to slaughter weight faster than more extensively-reared animals, and the peaks in figure  <dig> at around  <dig> days are due to this type of beef production.
finally, extensive beef suckler systems where beef cattle are reared more slowly on grass result in animals reaching slaughter weight at around  <dig> months; they result in the step in the number of beef cattle dying at around  <dig> days old.
while figure  <dig> shows the relative importance of different beef rearing regimes, figure  <dig> shows the ages at which animals die on farms, generally representing a loss to the farmer.
as would be expected, the majority of losses occur in young animals, succumbing to disease early in their life, although there is a small peak at  <dig> months, again probably due to the otm scheme.
frequency and distance of movements
figures  <dig> and  <dig> show the distributions of the number of times an animal moves in its life, and the distances over which animals are moved, respectively.
the extreme x-values in these figures should be treated with some caution -- it seems unlikely that an animal would travel  <dig>  km  in its lifetime, for example, although pedigree animals may be taken to many showgrounds during their lives.
figure  <dig> shows that most animals move only a few times during their lifetimes; a single move  is most common.
dairy animals are more likely to make two moves during their lifetimes than beef animals; this is most likely due to male dairy calves moving once to a fattening unit, and thence to slaughter.
figure  <dig> shows that while around 18% of animals move less than a kilometre during their life, there is then a very broad spread of distances travelled, with dairy cattle moving less far than beef cattle.
this pattern of most animals moving only a few times, and for a short distance has been described before in the uk  <cit> , though the longer-term analysis presented here shows a higher proportion of animals moving only once in their lifetime.
research on cattle movements in italy, portugal and sweden has shown that most movements are short-range , suggesting that this may be a common pattern across at least western europe  <cit> .
this is the first analysis to consider the total distance animals move in their lifetimes and its relationship to the number of times animals move.
there is a weak  but statistically significant correlation between the number of times an animal is moved in its life, and the total distance it moves, as illustrated in figure  <dig>  intuitively, animals that are moved more frequently would be expected to move further in their lifetimes, so it is a little surprising that this correlation is not stronger.
the duration of livestocks' stays on holdings is shown in figure  <dig>  around 34% of all recorded stays are transient, i.e.
the animal leaves the holding on the same day as it arrived there; these will be stays on markets.
the effects of the otm scheme are evident again, with a noticeable rise in stays of around  <dig> months.
from the point of view of understanding how cattle are moved, and potentially predicting future movement patterns, an interesting question is how habitual farmers are; if they are very habitual in their movement patterns, then one could reasonably assume that a farm will send its cattle to the same market next year that it did this year.
figure  <dig> enables this question to be addressed; it shows the number of times a movement occurs as a cumulative frequency distribution.
nearly a third of movements occur between  <dig> and  <dig> times, so some repetition of movements should be incorporated into any model of the uk cattle industry, but only to a limited extent.
changes in movement patterns over the past decade
given that the regulatory regime regarding animal movements has changed substantially in the recent past, particularly since the  <dig> fmd epidemic, it is worthwhile to try and assess what effect these changes have had on the movement of animals.
figures  <dig>   <dig>   <dig>  and  <dig> do this, on a yearly basis.
what is striking about these figures is how little has changed since  <dig> overall, in contrast to work by robinson and christley which considered movements in the period  <dig> to early  <dig>  <cit> .
the availability of data for a longer period of time shows that while there was an increase in cattle movement in the period they studied , that increase has not continued.
issues with the cts
the cts was not set up with the intention that it might be useful as a control system for epidemic diseases such as fmd; the  <dig> fmd outbreak in the uk and subsequent enquiries have led to changes in the collection of data, and the scope of such data.
specifically, the uk government has attempted to increase reporting of cattle movements by electronic means, and has introduced schemes to collect details on batch movements  of sheep, pigs, and goats  <cit> .
not all movements of cattle are required to be reported to radar.
specifically, movements to shared grazing lands are not required to be reported, and neither are movements between holdings that have been "linked".
the latter process is meant to allow farmers to move livestock between nearby holdings without the administrative burden of having to report the movements, but it has been abused by some farmers, who have "linked" holdings which are far away from each other  <cit> .
given the original purpose of cts, it is perhaps unsurprising that such movements need not be reported, but they may represent a substantial epidemiological risk.
a national audit office report noted that some keepers may be tempted to avoid the extra work associated with reporting animal movements, and that furthermore there may be financial advantages to deliberately contravening the identification and tracking requirements ; some examples of detected fraud were illustrated, although there is little idea as to the scale of the problem  <cit> .
defra has conducted a review of the livestock movement controls.
in addition to issues regarding abuse of "linked" holdings, the review concluded that the current regulations are overly complex and should therefore be simplified.
it additionally recommends that abattoirs should report the premises of departure of animals arriving at them, and that markets and collection centres should report the source and destination of animals passing through them, by electronic means.
regarding shared grazing lands, it suggests that a single land management unit should be formed consisting of the common land and any in-bye land to which cattle on the shared grazing have free access; movements into and out of this area would have to be reported, and would induce a standstill period.
it also advocates greater regulation of dealers and traders, specifically that those which hold livestock for mixing and sorting purposes be treated as collection centres , and that cts investigate movements of animals where a few days have passed between an "off" movement and the subsequent "on" movement, to attempt to determine whether the animals concerned stayed at an intermediate premises  <cit> .
in  <dig>  defra consulted on proposals to simplify the livestock movement rules and holding identifiers in england, although no changes have yet been proposed as a result of that consultation.
problems remain, however.
the current regulations are complex, which leads to errors in reporting, and are somewhat open to abuse.
furthermore, the data are not collected nor stored in a manner ideally suited to contact-network-based studies .
how important the delay between movements and their reporting to radar is in terms of intervention during an outbreak is an unanswered question; during the brief  <dig> fmd outbreak, livestock movement data were not available to researchers until the outbreak was over.
the importance of movements that are not required to be reported to radar in contact networks is unknown, and difficult to quantify nationally; a study in the outer hebridies showed that shared grazing land was a significant source of unreported contact between different keepers' cattle  <cit> .
CONCLUSIONS
radar's data provide an unprecedented opportunity for research into the life, movements, and death of uk cattle.
this article has concentrated on the demographics of cattle and their movements.
the cattle movement data may also be used to construct a contact network of uk cattle farms; this large-scale network is one of the best-characterised epidemiological networks available, making it a useful tool for research into the relevance of contact networks for epidemiology  <cit> .
there are some apparent similarities between the uk cattle herd's movement patterns and those of other european countries: there are seasonal peaks in movement volumes in spring and autumn, and most animals have only a few short movements in their lives, while a few cover much more substantial differences.
it would be worthwhile to consider the similarities and differences between different european countries' livestock movements patterns, particularly from the point of view of infectious diseases moving across the continent.
it is interesting to note that despite the significant changes to livestock movement regulations in the last decade, figures  <dig>   <dig>   <dig>  and  <dig> show that the overall pattern and volume of livestock movements have not changed a great deal since  <dig>  despite this, the disease susceptibility of the uk cattle herd  has fluctuated substantially during this period .
therefore, whilst demographic studies such as this are interesting in their own right, care must be taken when employing coarse measures of livestock movements for epidemiological problems.

 livestock identification and tracing legislation the movement of animals within the united kingdom is vital to the economics of the livestock industry, but carries with it the risk of transmitting infectious diseases across substantial geographic distances. over the last sixty years, the uk government has introduced increasingly detailed legislation relating to the identification and tracing of cattle. a requirement to identify cattle was first introduced in as part of the effort to eradicate bovine tuberculosis. in the movement of animals order required farmers to keep a record of all movements of bovines on or off their premises, and to store these records for three years. in in response to concerns over bovine spongiform encephalopathy, tighter controls were introduced. the bovine animals order required farmers to record the births of all calves and the identity of their dam, and to keep those records for ten years. dairy cattle were required to be marked and recorded within hours of birth, and other cattle within days. the movement of animals amendment order extended the period for which movement records had to be kept to years. the european economic community issued council directive 92/102/eec in which required movements of cattle to be recorded including origin and destination of the cattle concerned; cattle also had to be identified with an ear tag bearing a code of no more than characters. in the uk, this was implemented by the bovine animals order that order also required cattle farmers to register their holding with their local animal health office, and introduced the ear tag allocation system to ensure that every bovine animal had a unique identity. in the ministry of agriculture, fisheries, and food considered that implementing a computerised cattle traceability system was necessary to enable the lifting of the export ban on british beef. accordingly, the cts was established in september during the autumn of the "cattle count 2000" exercise was carried out, to register cattle born or imported before the first of july, and to confirm the location of cattle born between then and the twenty-seventh of september. cattle passports issued since september take the form of chequebook-style passports. these consist of: a front page with details of the animal's eartag, breed, date of birth, and genetic dam, as well as the passport's issue date; a short summary of previous holdings the animal has been on prior to the passport being issued; movement summary pages into which details of movements of the animal are entered; detachable movement cards by which movements may be reported to the cts; and a back cover for reporting the animal's death. as of january it has been a legal requirement to report all movements of bovine animals to the cts. the british cattle movement service is responsible for running the cts. the rapid analysis and detection of animal-related risks project was started in by the department for environment food and rural affairs to collect veterinary surveillance data from different sources in the uk. it is being developed and released in phases between and phase took place in march and contained information on the uk cattle population as well as data on salmonella cases. the cattle movement data contained within radar are supplied by the bcms. cattle movements are reported to the bcms by the holdings at both ends of the movement: i.e. an "off" record is created at one holding, and an "on" record at the other. part of radar phase has been to turn unpaired movements into a life history for each animal. first, duplicate movement records are discarded, as are movements before the birth date, or after the death date. a record of the animal's life history is then generated, consisting of a series of stays at locations, as can best be described by the extant movement records. these movement data have been used as the basis for a broad range of epidemiological models, as well as a smaller body of work on the demographics of the uk cattle industry. movement control legislation movements of bovines since have not occurred in an unchanging regulatory environment. there have been movement restrictions in the face of specific disease outbreaks: nationwide during the foot and mouth disease epidemic and more locally during the smaller epidemic; and from september onwards to tackle bluetongue. additionally, regulations have been introduced to try and make the uk cattle herd less susceptible to disease transmission. a six-day standstill period was introduced on august by the disease control order 2003; this meant that if any sheep, goats, cattle or pigs were moved onto a farm, then no sheep, goats, or cattle could be moved off that farm for days. as an attempt to control the spread of btb, pre-movement testing of bovines was introduced in a phased manner by the tuberculosis order the tuberculosis order the tuberculosis order and the tuberculosis order bovines on a farm with a 1- or 2-year btb testing interval in england and wales being moved must have been tested for btb within days. in scotland, animals must additionally be tested 60- days post-movement. previous work some other previous work on related questions based on radar data has been published. defra's farming statistics team have published several "cattle books" containing descriptive statistics on the size, location, breed make-up, and so on of the uk cattle herd. the most recent of these described the cattle herd in with population statistics such as number and ages of cattle, their breeds and geographic distribution captured as at june. statistical analyses of bcms movement data have highlighted biases in the reporting of birth dates, and the fact that certain classes of movements are under-reported. two seasonal peaks in movement volume are observed in the spring and autumn, and most movements of livestock occur during the working week, with a peak on wednesdays. while most animals only move a short distance, there are a small number of animals that move much further. mitchell and colleagues described the mean distance moved as km, and the maximum as km, while christley and colleagues considered february and found the median movement distance to be km, and the maximum km. the requirement to record the birth, death, and movements of cattle exists across the eu; various member states' data have been employed by researchers interested in agricultural economics or epidemiology. for example, in most cattle moved within portugal were young beef stock, and most of the cattle were found in the north of the country; movements in the south of the country were less frequent, but tended to be substantially larger. natale and colleagues constructed a static network model of the italian cattle herd based on movements recorded in as well as considering the types of holdings that participated in movements, and the distances of movements. they used disease simulation to suggest that targetting movement restrictions to affect central farms could be a useful disease control tool in the event of an outbreak. in sweden, nöremark and colleagues have considered data on cattle and pigs together; similarly to the uk, they found peaks in cattle movements in the spring and autumn, reporting bias in dates, and that most movements of cattle and pigs occurred over a relatively short distance, with a few much longer movements; they went on to perform network analyses of these movement data, and considered the types of holding that were of greatest epidemiological significance within the network. this article in this article, radar data for the past decade are used to illustrate the demographics of uk cattle, and to consider trends in movement patterns across that decade. this long-term approach is in contrast to previous authors who have typically concentrated on a single year, or a few years at most. the distribution of number of movements, their timings, and the types of holding involved in movement cattle are analysed, as well as the number of cattle in the uk, and the ages and locations at which they die. since livestock movements are important for the spread of infectious diseases, the frequency and distance cattle move are analysed, as well as how frequently contacts between farms recur.  movement numbers, timing, and holding types the extract from radar supplied by defra contained movements of bovines in the uk up to april the radar livestock movements table contains, records, representing the movements of, distinct animals between distinct locations. the number of movements in each month of to is plotted in figure the large spike in the autumn of is an artifact of cattle count when previously unregistered cattle were registered, and movements from their birth locations to their then-current ones inferred. the quality of pre- movement data remains questionable, however. the number of movements beginning and leaving premises of different types in and is shown in table 1; note that births and deaths will not appear in these figures. "count" indicates the number of holdings of that type. the first column contains the source holding type. holding type abbreviations are defined in table italic numbers show where the observed number was greater than the expected number, bold numbers show where the observed number was less than the expected number, and numbers in normal type show where the observed number was within movement of the expected number the first column contains the source holding type. holding type abbreviations are defined in table livestock numbers and ages radar contains data on, animals, of which, have a birth date but no death date, giving an upper bound on the number of cattle alive in the uk at the time the data were provided. the ages at which cattle die are shown in figure 2; the peaks are at days, around months, around months, and around months. table shows the number of animals that died on each holding type; 99% of deaths occur on animal holdings or at red meat slaughterhouses. figures and show the ages at which cattle die on red meat slaughterhouses and animal holdings, respectively. frequency and distance of movements the distribution of number of times an animal moves in its life is shown in figure the x-axis has been truncated at 15; the largest number of moves in a lifetime according to radar is the distributions are shown for all cattle, as well as beef and dairy cattle. the distribution of distances animals move in their life is shown, using a log scale, in figure again subdivided into beef and dairy cattle. the x-axis has been truncated at km; the greatest distance moved in the life of a single animal according to radar is km. the relationship between the number of times an animal moved in its life and the total distance it moved in its life is examined in figure 7; coloured hexagonal binning has been used to illustrate the density of animals across the figure. spearman's rank correlation coefficient ρ =, p < × 10- showing a weak but statistically significant correlation between distance moved in life and number of movements in life. the distribution of length of time animals spend on a particular holding is shown in figure the x-axis is truncated at days, and the y-axis is logarithmic; the longest stay of an animal on a location according to radar was days. the peaks are at around months, and around months. changes in movement patterns over the past decade the distances of movements across the years 1999- are shown in figure 10; the box and whisker plots show the median and interquartiles and the central ninety-five percentiles, whilst the blue line indicates the mean. the change in movement batch sizes across the same time period is shown in figure the in- and out-degrees of farms taking a single static network for each year are shown in figure the number of cattle moved onto and off farms in a year is shown in figure discussion movement numbers, timing, and holding types the foot and mouth disease epidemics in and are both noticeable as a drop in movement volume in figure even at the height of the epidemic, however, there was still a certain amount of movement going on; licenses were granted for movements within the infected area, from the uninfected area to the infected area, and within the uninfected area. as would be expected, the vast majority of movements involve agricultural holdings, markets, and slaughterhouses. table shows that agricultural holdings are net exporters of animals, the numbers of animals entering and leaving markets are roughly the same, and that slaughterhouses are net importers of animals. since animals are born on farms, pass through markets, and die at slaughterhouses, these figures are reassuringly predictable. comparing tables and shows that there were substantially fewer movements between animal holdings in 2008- than would be expected by chance; the majority of this difference is explained by the greater number of movements from animal holdings to markets and slaughterhouses, and from markets to animal holdings. similarly, there is very little movement of animals from market to market, animals instead moving to or from animal holdings. as well as being an interesting insight into the structure of the cattle industry in the uk, these figures would be valuable for constructing an economic model of livestock movements, which in turn might be a useful technique for predicting future patterns of livestock movement in the uk. livestock numbers and ages figures and and table provide some insight into the mortality of british cattle. table shows unremarkably that the majority of cattle deaths occur at red meat slaughterhouses; also that animal holdings and red meat slaughterhouses account for nearly all cattle deaths between them. in the light of concerns about the risk bse posed to human health, the fresh meat regulations were introduced on march they banned cattle that were over thirty months old from entering the human food chain; instead the animals were slaughtered, and farmers paid compensation under the over thirty months slaughter scheme. this ban was relaxed on november when older cattle were again eligible to enter the human food chain, provided they tested negative for bse. the effect of this so-called "over thirty month rule" is clear to see in figures and -- there is a substantial spike in the number of cattle dying at thirty months old. figure shows the distribution of ages of animals dying at red meat slaughterhouses. there is a substantial peak at around a week of age, particularly among dairy cattle; male dairy calves are worth very little, so some are slaughtered at a young age to save the cost of rearing them; rennet may also be extracted from the abomasums of calves. animals are typically slaughtered for veal at around months of age; it is clear from figure that this remains a insignificant beef product in the uk. intensively reared beef is produced from beef and dairy animals of around months of age; these animals are fed cereals and concentrates and so come to slaughter weight faster than more extensively-reared animals, and the peaks in figure at around days are due to this type of beef production. finally, extensive beef suckler systems where beef cattle are reared more slowly on grass result in animals reaching slaughter weight at around months; they result in the step in the number of beef cattle dying at around days old. while figure shows the relative importance of different beef rearing regimes, figure shows the ages at which animals die on farms, generally representing a loss to the farmer. as would be expected, the majority of losses occur in young animals, succumbing to disease early in their life, although there is a small peak at months, again probably due to the otm scheme. frequency and distance of movements figures and show the distributions of the number of times an animal moves in its life, and the distances over which animals are moved, respectively. the extreme x-values in these figures should be treated with some caution -- it seems unlikely that an animal would travel km in its lifetime, for example, although pedigree animals may be taken to many showgrounds during their lives. figure shows that most animals move only a few times during their lifetimes; a single move is most common. dairy animals are more likely to make two moves during their lifetimes than beef animals; this is most likely due to male dairy calves moving once to a fattening unit, and thence to slaughter. figure shows that while around 18% of animals move less than a kilometre during their life, there is then a very broad spread of distances travelled, with dairy cattle moving less far than beef cattle. this pattern of most animals moving only a few times, and for a short distance has been described before in the uk, though the longer-term analysis presented here shows a higher proportion of animals moving only once in their lifetime. research on cattle movements in italy, portugal and sweden has shown that most movements are short-range, suggesting that this may be a common pattern across at least western europe. this is the first analysis to consider the total distance animals move in their lifetimes and its relationship to the number of times animals move. there is a weak but statistically significant correlation between the number of times an animal is moved in its life, and the total distance it moves, as illustrated in figure intuitively, animals that are moved more frequently would be expected to move further in their lifetimes, so it is a little surprising that this correlation is not stronger. the duration of livestocks' stays on holdings is shown in figure around 34% of all recorded stays are transient, i.e. the animal leaves the holding on the same day as it arrived there; these will be stays on markets. the effects of the otm scheme are evident again, with a noticeable rise in stays of around months. from the point of view of understanding how cattle are moved, and potentially predicting future movement patterns, an interesting question is how habitual farmers are; if they are very habitual in their movement patterns, then one could reasonably assume that a farm will send its cattle to the same market next year that it did this year. figure enables this question to be addressed; it shows the number of times a movement occurs as a cumulative frequency distribution. nearly a third of movements occur between and times, so some repetition of movements should be incorporated into any model of the uk cattle industry, but only to a limited extent. changes in movement patterns over the past decade given that the regulatory regime regarding animal movements has changed substantially in the recent past, particularly since the fmd epidemic, it is worthwhile to try and assess what effect these changes have had on the movement of animals. figures and do this, on a yearly basis. what is striking about these figures is how little has changed since overall, in contrast to work by robinson and christley which considered movements in the period to early. the availability of data for a longer period of time shows that while there was an increase in cattle movement in the period they studied, that increase has not continued. issues with the cts the cts was not set up with the intention that it might be useful as a control system for epidemic diseases such as fmd; the fmd outbreak in the uk and subsequent enquiries have led to changes in the collection of data, and the scope of such data. specifically, the uk government has attempted to increase reporting of cattle movements by electronic means, and has introduced schemes to collect details on batch movements of sheep, pigs, and goats. not all movements of cattle are required to be reported to radar. specifically, movements to shared grazing lands are not required to be reported, and neither are movements between holdings that have been "linked". the latter process is meant to allow farmers to move livestock between nearby holdings without the administrative burden of having to report the movements, but it has been abused by some farmers, who have "linked" holdings which are far away from each other. given the original purpose of cts, it is perhaps unsurprising that such movements need not be reported, but they may represent a substantial epidemiological risk. a national audit office report noted that some keepers may be tempted to avoid the extra work associated with reporting animal movements, and that furthermore there may be financial advantages to deliberately contravening the identification and tracking requirements; some examples of detected fraud were illustrated, although there is little idea as to the scale of the problem. defra has conducted a review of the livestock movement controls. in addition to issues regarding abuse of "linked" holdings, the review concluded that the current regulations are overly complex and should therefore be simplified. it additionally recommends that abattoirs should report the premises of departure of animals arriving at them, and that markets and collection centres should report the source and destination of animals passing through them, by electronic means. regarding shared grazing lands, it suggests that a single land management unit should be formed consisting of the common land and any in-bye land to which cattle on the shared grazing have free access; movements into and out of this area would have to be reported, and would induce a standstill period. it also advocates greater regulation of dealers and traders, specifically that those which hold livestock for mixing and sorting purposes be treated as collection centres, and that cts investigate movements of animals where a few days have passed between an "off" movement and the subsequent "on" movement, to attempt to determine whether the animals concerned stayed at an intermediate premises. in defra consulted on proposals to simplify the livestock movement rules and holding identifiers in england, although no changes have yet been proposed as a result of that consultation. problems remain, however. the current regulations are complex, which leads to errors in reporting, and are somewhat open to abuse. furthermore, the data are not collected nor stored in a manner ideally suited to contact-network-based studies. how important the delay between movements and their reporting to radar is in terms of intervention during an outbreak is an unanswered question; during the brief fmd outbreak, livestock movement data were not available to researchers until the outbreak was over. the importance of movements that are not required to be reported to radar in contact networks is unknown, and difficult to quantify nationally; a study in the outer hebridies showed that shared grazing land was a significant source of unreported contact between different keepers' cattle.  radar's data provide an unprecedented opportunity for research into the life, movements, and death of uk cattle. this article has concentrated on the demographics of cattle and their movements. the cattle movement data may also be used to construct a contact network of uk cattle farms; this large-scale network is one of the best-characterised epidemiological networks available, making it a useful tool for research into the relevance of contact networks for epidemiology. there are some apparent similarities between the uk cattle herd's movement patterns and those of other european countries: there are seasonal peaks in movement volumes in spring and autumn, and most animals have only a few short movements in their lives, while a few cover much more substantial differences. it would be worthwhile to consider the similarities and differences between different european countries' livestock movements patterns, particularly from the point of view of infectious diseases moving across the continent. it is interesting to note that despite the significant changes to livestock movement regulations in the last decade, figures and show that the overall pattern and volume of livestock movements have not changed a great deal since despite this, the disease susceptibility of the uk cattle herd has fluctuated substantially during this period. therefore, whilst demographic studies such as this are interesting in their own right, care must be taken when employing coarse measures of livestock movements for epidemiological problems. 
despite reservations about the accuracy of these data, they represent a large and valuable body of information about the demographics of the uk cattle herd and its contact structure. in this article, a range of demographic data about uk cattle, and particularly their movements, are presented, as well as yearly trends in the patterns of movements. despite a substantial number of regulatory interventions during the last decade, movement patterns show no clear trend since the observed patterns in the repeatability of movements, the types of holdings involved in movements, the distances and frequencies of cattle movements, and the batch sizes involved give an insight into the structure of the uk cattle industry, and could act as the basis for a predictive model of livestock movements in the uk. there is no clear trend to movement patterns in the uk since a clear seasonal pattern is evident in the number of movements of cattle, as are the reductions in movement volume due to foot and mouth disease outbreaks in and the distribution of ages of cattle at their time of death is multimodal, and the impact of the over thirty months rule is marked. most animals move only a short distance and a few times in their life. most movements occur between agricultural holdings, markets, and slaughterhouses, and there is a non-random pattern to the types of holdings movements occur between.
 the united kingdom government has been recording the births, deaths, and movements of cattle for the last decade. despite reservations about the accuracy of these data, they represent a large and valuable body of information about the demographics of the uk cattle herd and its contact structure. in this article, a range of demographic data about uk cattle, and particularly their movements, are presented, as well as yearly trends in the patterns of movements.  a clear seasonal pattern is evident in the number of movements of cattle, as are the reductions in movement volume due to foot and mouth disease outbreaks in and the distribution of ages of cattle at their time of death is multimodal, and the impact of the over thirty months rule is marked. most movements occur between agricultural holdings, markets, and slaughterhouses, and there is a non-random pattern to the types of holdings movements occur between. most animals move only a short distance and a few times in their life. most movements between any given pair of holdings only occurred once in the last years, but about a third occurred between and times in that period. there is no clear trend to movement patterns in the uk since  despite a substantial number of regulatory interventions during the last decade, movement patterns show no clear trend since the observed patterns in the repeatability of movements, the types of holdings involved in movements, the distances and frequencies of cattle movements, and the batch sizes involved give an insight into the structure of the uk cattle industry, and could act as the basis for a predictive model of livestock movements in the uk. 