TSEs: The case for the relaxation of sheep controls

A NSA report assessing the current situation regarding ovine TSE controls and making recommendations for progress towards the relaxation of relevant regulations. Please direct any questions to enquiries@nationalsheep.org.uk.

Click here for comments from other industry organisations supporting NSA's stance on TSEs.

Contents

  1. Introduction
  2. Current ovine TSE controls
  3. A comparison of cattle and sheep controls
  4. Costs of present controls on the industry
  5. Alternatives and potential amendments to TSE controls in sheep
  6. NSA recommendations
  7. Download this report and/or a summary of this report

1. Introduction

Transmissible Spongiform Encephalopathies (TSEs) are a group of degenerative fatal diseases affecting the brain. TSEs include scrapie in sheep and goats, Bovine Spongiform Encephalopathy (BSE) in cattle and Creutzfeldt–Jakob Disease(CJD) in humans.

Scrapie exists in two similar but unrelated forms: classical and atypical. Classical scrapie is contagious between sheep. Lateral transmission of classical scrapie occurs naturally, possibly through consumption of or exposure to infected placentas. Infection may also be transmitted to lambs through the milk of infected ewes. Classical scrapie is seen most commonly in animals aged between two and five. Atypical scrapie (Nor98) is a spontaneously occurring, sporadic, degenerative brain condition of older sheep and goats (generally over five years of age).

Regulations for the monitoring of ovine TSEs were brought in as a related precaution alongside BSE controls following the BSE crisis of the mid-1990s, as it was feared BSE might cross species from cattle to sheep and that BSE may present in sheep in the form of scrapie. The practice of feeding meat and bone meal in ruminant rations, and potentially feeding infected material, was identified as a potential risk to human health. Following the BSE crisis the feeding of mammalian protein to ruminants was prohibited, with strict controls set in place. 

In the field, over nine million samples have been taken by 2014 across all EU member states and not a single case of BSE being transmitted naturally to sheep has ever been found. In laboratory conditions it was found to be possible to infect sheep with BSE, although this was achieved only by feeding fresh infected brains, something never practised. In addition, BSE infection of sheep achieved under laboratory conditions showed that contamination was not just restricted to Specified Risk Material (SRM) with up to 30% of infectivity distributed through edible parts of the sheep carcase, including in young sheep. Yet TSE controls only require that SRM material be removed from sheep over 12 months of age (as defined by the emergence of the first permanent incisors), suggesting it was accepted that any risk of BSE crossing species naturally was low.

The similarities between BSE and scrapie characteristics led to theories that scrapie could be a risk to human health. Extensive research has shown BSE and scrapie to be unrelated diseases and found no evidence of a human health risk from ovine TSEs. Scrapie is a long standing and naturally occurring disease of sheep that is a challenge for sheep productivity rather than any risk to human health.

On 1st March 2013 the requirement to test healthy slaughtered cattle for BSE ceased for all animals born in EU states (except Romania and Bulgaria). As BSE testing requirements are being relaxed, the rules regarding ovine TSE monitoring, which were originally introduced as a parallel precaution to these requirements, must also be reviewed. These regulatory practices create inconvenience and confusion, are costly to the sheep industry, the government and the national economy, and undermine confidence in sheep farming.

2. Current ovine TSE controls: Removal of Specified Risk Material (SRM)

Regulation (EC) No. 999/2001 of the European Parliament requires the removal of SRM from the carcases of UK sheep slaughtered for human consumption, in order to prevent this tissue entering the human food chain. Theoretically, SRM includes those tissues which might potentially harbour detectable TSE infectivity. The parts of UK sheep presently specified as SRM vary between sheep aged under 12 months and sheep aged over 12 months (as defined by the emergence of the first permanent incisors).

  • For sheep of all ages: the spleen and ileum
  • For sheep aged over 12 months or with a permanent incisor erupted through the gum: the skull (including the brain and eyes), tonsils and spinal cord

It is an offence in the UK to remove the spinal cord except by splitting the whole vertebral column or removing a section of the whole vertebral column including the spinal cord. Other EU states only require the removal of as much SRM as possible, while in the UK 100% SRM removal is compulsory; the UK is therefore gold plating European law.

Current ovine TSE controls: UK TSE Testing Programme

Regulation (EC) No. 999/2001 of the European Parliament requires that EU member states perform active surveillance of TSEs in sheep, goats and cattle. The UK must test the following quotas of sheep annually:

  • 10,000 sheep which die or are killed other than for human consumption (fallen stock) aged over 18 months
  • 10,000 sheep which are slaughtered for human consumption aged over 18 months

The UK must also test sheep from scrapie infected flocks (see table).
The 10,000 fallen stock samples are obtained from carcases chosen for testing randomly at animal by-products plants and on routine inspections by Animal Health and Veterinary Laboratories Agency (AHVLA). The Government arranges and funds the collection, testing and destruction of animals chosen for sampling.

Current ovine TSE controls: Compulsory Scrapie Flocks Scheme (CSFS)

Regulation (EC) No. 1915/2003 of the European Union imposes compulsory controls on sheep flocks found to be infected with scrapie. In flocks where there is a confirmed case of classical scrapie the following options are available:-

  • Genotyping of the flock and killing of sheep with susceptible genotypes
  • Whole flock killing (this is an exceptional measure)

The UK Government funds the implementation of the CSFS domestically. In flocks where a case of atypical scrapie is confirmed it is possible to opt for monitoring rather than culling.

3. A comparison of cattle and sheep controls: Overview of regulations for cattle

In the UK the requirement to test healthy slaughtered cattle for BSE ended on 1st March 2013. This applies to cattle born in EU Member States (except Bulgaria and Romania) – see table below. Opinion published by the European Food Safety Authority (EFSA) in December 2010 indicates that change to the testing regime is likely to have a minimal impact on the potential for animals with classical BSE entering the food chain. The Spongiform Encephalopathy Advisory Committee (SEAC) has also advised that in the short-term there is likely to be an insignificant additional risk to human health as a result of making this change.

Clearly it is considered that this relaxation of BSE controls will not present a significant increase in the human health risk associated with BSE.

A comparison of cattle and sheep controls: Comparison with regulations for sheep

Ovine TSE controls were originally introduced alongside BSE testing regulations as a precautionary measure, due to concern over the potential transfer of BSE to sheep and a possible relation between BSE and scrapie. There is currently no evidence of the natural occurrence of BSE in sheep or that BSE and scrapie are related. There is also no evidence of a risk to human health from ovine TSEs. Cattle are susceptible to the natural contraction of BSE, the disease strongly linked to variant CJD in humans. In light of these facts, it is logical that as the relaxation of BSE regulations for cattle is not considered a significant human health risk, a relaxation of ovine TSE controls would constitute an even lesser risk, if any.

A comparison of cattle and sheep controls: The decline in scrapie cases

Confirmed cases of scrapie in the UK have declined substantially over the last decade - see graph below. The drop in cases of classical scrapie has been credited to the implementation of a selective breeding programme aimed at reproducing genotypes resistant to classical scrapie and the culling of susceptible genotypes. Although atypical scrapie can be contracted by genotypes resistant to classical scrapie, atypical scrapie is not transmitted naturally between individuals and emerges only sporadically in a flock.

4. Costs of present controls on the industry: Costs of carcase splitting

The removal of the spinal cord from sheep aged over 12 months or with a permanent incisor erupted through the gum is currently undertaken in the UK through the process of carcase splitting, in which carcases are halved lengthways down the vertebral column. The costs associated with this, according to information gathered by NSA, include:-

  • Slower slaughter line speeds: Carcase splitting increases the time taken to process an animal on the slaughter line, resulting in slowing slaughter lines by in excess of 50%. Assuming the cost of running an average slaughter line is £700 per hour and the throughput without splitting is 500 lambs per hour, this effect increases the cost of this part of the slaughter process per carcase from £1.40 to over £2.80. The slowing of slaughter lines by splitting leads to an estimated annualised increased cost to processors of approximately £262,000. Although this cost is borne by the processor directly, it is passed to farmers through lower carcase values.
  • Devaluation of the carcase: Splitting devalues the carcase, as spinal cord removal represents a clear identification of a carcase as coming from an older animal. Buyers also prefer ‘whole’ carcases as splitting limits butchery options. The consequent devaluation of carcases through splitting is estimated at 40%, so based on an assumed average un-split carcase value of £80, this is a value reduction of £32 per split carcase. Assuming 14 million lambs are slaughtered each year, and 5% (700,000) of those are split, the annual average lost opportunity cost of carcase splitting is approximately £22.4 million. This cost is borne by farmers through lower carcase values. The devaluation of carcases caused by splitting also limits opportunities for the export of UK sheep meat (see below).
  • Checking for teeth in live markets: There is a cost to live markets of checking for teeth in sheep which pass through them to establish whether they will require splitting. Identifying sheep with visible permanent incisors enables live markets to direct sheep towards suitable buyers. According to Eblex, 2.156 million old season lambs (commonly defined as lambs aged between a year and two years, having no more than one pair of permanent incisors) passed through British auction markets in 2012. Assuming a cost of checking for teeth of 30p per old season lamb, the total cost to British auction markets of tooth checking in 2012 was £646,800.

Without considering its effect on the export potential and domestic competitiveness of UK sheep meat, the estimated total yearly cost of carcase splitting to the UK sheep industry is approximately £23,308,800.

Costs of present controls on the industry: Cost to exports by association

Implementation of strict ovine TSE controls diminishes the reputation of UK sheep meat on the export market. The enforcement of stringent rules around scrapie gives the impression to potential importers that UK sheep are not healthy animals that produce safe, high quality meat, thereby reducing international demand for UK sheep meat. This effect is enhanced by the popular association of scrapie with BSE. As mentioned above, the export potential of UK sheep meat is also reduced by the practice of splitting carcases. It is difficult to put a figure on this disadvantage, however export demand is growing and the UK is not optimising its contribution to export values.

5. Alternatives and potential amendments to TSE controls on sheep: Spinal cord removal by suction

Elsewhere in the EU, notably in France, the spinal cord of older sheep is removed by sucking SRM from the carcase, thereby removing the necessity to split the carcase and avoiding the associated devaluation suffered by split carcases. Removal by suction has costs of its own, however, including:-

  1. The capital cost of the equipment for processors, estimated at £8,000-£12,000 per unit (Source: Eblex, 2012). This cost is likely to prove too great to allow the successful introduction of spinal cord removal by suction in the UK.
  2. Continued reduction in slaughter line speed. Indications are that alternative systems of spinal cord removal are no quicker than splitting.
  3. Continued carcase devaluation. The carcase damage involved in removal of the spinal cord by suction can be seen as an indicator of an older animal in the same way as that caused by splitting; although they remain whole, carcases which have undergone removal by suction therefore continue to suffer devaluation.

In addition, suction equipment is not reliably able to thoroughly remove all the SRM from a carcase so would require an end to the gold plating applied to the current EU legislation by the Food Standards Agency.

Alternatives and potential amendments to TSE controls on sheep: Carcase splitting at emergence of the second pair of permanent incisors

Domestic regulations currently require carcases to be to split if the animal is over 12 months old or a single permanent incisor has emerged. Lambs’ incisors generally emerge in pairs and the emergence of just a single incisor is unlikely. The eruption of a lamb’s first incisors is unpredictable and can occur at varying points in development and so their emergence therefore cannot provide an accurate measure of an animal’s age, and an animal aged significantly under 12 months may have its first set of incisors. As the earliest onset form of scrapie does not commonly occur until two years of age, the current splitting of carcases aged 12 months and potentially younger is unnecessary. Upland farmers grazing some of our most iconic indigenous breeds are particularly badly hit by the 12-month/first incisor rule. The hard terrain of upland areas often results in lambs taking longer to reach killing weights, but grazing this type of sheep in less favoured area has environmental, social, health and economic benefits that go beyond the direct farming economy and should therefore be supported (Click here for NSA’s The Complementary Role of Sheep in Less Favoured Areas report for the full range of benefits provided by sheep grazing in upland areas of the UK.)

Introducing the splitting of carcases where a second set of permanent incisors have emerged or the animal has reached 24 months of age would prevent the splitting of carcases too young to be at risk of scrapie, while ensuring that the spinal cord would still be removed from all sheep of the age commonly susceptible to the disease.

Alternatively, a precedent has already been set with sheep identification rules that the end of June following the year of birth marks the 12-month age for all lambs regardless of when precisely they were born in the year previous. Using the end of June as a cut off-date, after which all carcases would be split, would reduce the time and cost of checking for teeth. It would also be far more transparent and farmers, markets and abattoirs would all be very clear on where they stood.

6. NSA recommendations: The NSA makes the following recommendations, as a matter of priority:-

  1. The EU Commission should, with urgency, give its attention to the European Food Safety Authority (FSA) report on Scientific Opinion on BSE/TSE Infectivity in Small Ruminant Tissues published in 2010 and act on the recommendations it contains, including its suggestions for the improvement of data collection and risk assessment in this area. Read the report at www.efsa.europa.eu/en/efsajournal/doc/1875.pdf.
  2. TSE controls for sheep should be relaxed and the practice of carcase splitting ended. There is no evidence that BSE can be transferred to sheep in non-laboratory conditions, feed controls no longer allow mammalian protein to be fed to ruminants. and there is no evidence of any link between scrapie and degenerative brain disease in cattle or humans. In spite of this, carcase splitting continues to incur huge costs to the sheep industry and reduce the competitiveness of UK sheep meat domestically and on the world market.
  3. As an immediate measure we would recommend one of two alternatives be adopted for determining when carcases have to be split and SRM removed: a) the 12-month age limit for carcase splitting should be interpreted as being the end of June following the year of birth rather than using visible permanent incisor eruption. This would reduce the time and cost of checking for teeth. There is already a precedent for this system of age identification being used for the EID tagging of slaughter lambs; b) or the age at which sheep are required to be split should be increased to 24 months or where a second pair of permanent incisors has emerged. As the earliest onset form of scrapie does not commonly occur until two years of age, the current splitting of carcases aged twelve months and potentially younger is unnecessary. Either alternative would result in a dramatic fall in the number of lambs being split and would take considerable uncertainly away from farmers, as emergence of the first incisors (which almost always erupt as a pair) is unpredictable and can occur at varying ages and points in development, meaning carcases which are not older animals are therefore sometimes identified as older and unfairly devalued as a result.
  4. The Food Standards Agency (FSA) should cease insisting on 100% SRM removal in UK abattoirs when other EU Member States only require the removal of as much SRM as possible. The UK is gold plating a European requirement and the burden on abattoirs could be reduced without any changes being made to the law.
  5. Scrapie testing in sheep should continue in order to further improve the health status and productivity of sheep.  Scrapie is a long standing and naturally occurring disease of sheep that is a challenge for sheep productivity (rather than any risk to human health) and so the UK TSE Testing Programme and Compulsory Scrapie Flocks Scheme (CSFS) should continue as Government-funded services.

7. Download this report and/or a summary of this report below.

Downloads

Scroll to the bottom of the page to download a summary of this report and a printable PDF of the full report.
Scroll to the bottom of the page to download a summary of this report and a printable PDF of the full report.