Defra

Main menu

• Contact us
• Access to information
• News
• Site A-Z
• Search

Section navigation

Disease control & eradication

Legislation

Other TSEs (inc. Scrapie)

Cattle disposal schemes

Publications

Public health issues

Science & research

Statistics

Other useful links

BSE site directory

BSE FAQ

BSE general Q&A

Glossary

Contacts

Links

BSE: Disease control & eradication - the feed ban - born after the July 1988 ban (BAB) cases

[back to The feed ban]

The July 1988 ban on feeding ruminant-derived protein to ruminants (e.g. cattle, sheep, goats and deer) in Great Britain, significantly reduced the number of cattle exposed to BSE infection. There was a marked decrease in the number of confirmed BSE cases born after the July 1988 ban (BAB cases). The prolonged incubation period of BSE delayed the corresponding effect on the annual confirmation rate by approximately five years. Detailed investigations of the initial BAB cases indicated that the most likely source of infection in these cases was the continued use of feed manufactured before the 1988 ban. In November 1994, GB implemented an EU-wide ban on the feeding of mammalian protein to ruminants.

Reasons for BAB cases

By autumn 1994 the decline in the epidemic, which commenced in early 1993, was occurring more slowly in the northern and eastern regions of England in which the proportion of pigs relative to cattle was highest. At that time pig and poultry feed could legitimately contain ruminant meat and bone meal (MBM), and in such regions there was an increased risk of cross contamination of ruminant feed with MBM, either in the feed mill, during transport, or on farm. Samples of cattle feed taken on a farm in August 1994 were shown to contain ruminant MBM, demonstrating that such cross-contamination could occur. A 1994 case-control study looked closely at possible causes of BSE in BAB animals. This study found no statistical significance of horizontal or vertical transmission of BSE in BAB cases and concluded that a food borne source of infection was the most likely explanation.

The continued presence of BSE infectivity in MBM suggested failings in the Specified Risk Material (SRM), then called Specified Bovine Offals (SBO), controls. The most likely source of this problem came from the practice of splitting bovine skulls. Until August 1995, when the practice was banned, bovine skulls could be split to remove the brain for disposal as SBO, allowing the remaining bone to be sent for rendering to meat and bone meal. Brain material sometimes remained in the skull, providing a significant route by which infectivity could enter MBM. Other SBO may have been inadequately separated from non-SBO material, providing another potential route of infection. Research has since shown that some of the rendering systems in use until December 1994 had little effect on BSE infectivity. Current research indicates that 1 milligram (one thousandth of a gram) of unprocessed brain from a clinically affected cow, fed to calves, can cause infection and eventually disease.

Prevention of Cross Contamination

In August 1995, the controls on the handling of SBOs were strengthened to further protect animal health. They required that the whole skull (with the exception of the tongue) be disposed of as an SBO and that rendering plants use dedicated lines for the processing of SBO tissues. In April 1996 the use of mammalian MBM was banned in all feed for livestock, fish and equine animals. This was not as a result of fears that non-ruminant species may catch BSE by oral exposure, but to remove any possible risk of cross-contamination of cattle rations in feed mills, during transport or on farms with MBM intended for other species. A Voluntary Feed Recall Scheme, launched in June 1996, encouraged removal of residual stocks of mammalian MBM from UK farms, feed mills and feed merchants. The VFR Scheme offered free collection and disposal of residual stocks of feed. From 1 August 1996 it became an offence (except in very tightly defined and controlled circumstances) to hold mammalian MBM on farms or in feed mills and premises where livestock feed is used, produced, prepared or stored.

BSE: Disease Control & Eradication - The Feed Ban - Born After the Reinforced Ban (BARB) Cases

Additional measures to prohibit the feeding of mammalian MBM to all farmed livestock have been in place in the United Kingdom since 1 August 1996. This is regarded as the date the reinforced feed ban became effective. BSE cases born after July 1996 are referred to as born after the reinforced ban (BARB) cases. The State Veterinary Service carries out a detailed epidemiological investigation into all BARB cases in Great Britain.

Incidence

The tables below contain details for the cases in animals born after the reinforced feed ban of August 1996 that have been confirmed during the last 12 months, in Great Britain and in Northern Ireland. Details of previous cases are available in a separate table.

A comparison of the number of BSE cases born before and after the 1996 feed ban provides evidence of its impact:

• At the end of August 2005 in Great Britain, there were over 44 000 BSE cases in cattle born between July 1988 and July 1996, but only 110 BARB cases born between August 1996 and August 2005;
• At the end of August 2005 in Northern Ireland, there were almost 600 BSE cases in cattle born between January 1989 and July 1996, but only 16 BARB cases born between August 1996 and August 2005.·

There have been over 184 000 BSE cases in the UK in total.

Most BARB cases are detected by active surveillance and the majority of those detected by active surveillance have been emergency slaughtered animals presented to the Over Thirty Month Scheme (OTMS) for disposal.

Reasons for BARB Cases

The UK prohibited the use of mammalian MBM in all feed for livestock, fish and equine animals in April 1996. In December 2000 the European Union decided to prohibit the feeding of processed animal protein (PAP) to all farmed animals from January 2001. The ten new Member States joining the EU in 2004 may not have implemented full BSE controls until after January 2001.

One possible reason for BARB cases is the contamination of cattle feed ingredients with mammalian MBM handled, stored and transported outside the UK, prior to the 2001 EU-wide ban. This hypothesis comes from a detailed analysis of epidemiological data on the first 59 cases which has been considered by the EU's Scientific Steering Committee and more recently by the European Food Safety Authority. There is also evidence from epidemiological investigations into BARB cases that some cases result from the persistence of infection in feed stores beyond the dates of the official feed ban.

In November 2004, Defra appointed an independent expert, Professor William Hill FRS of the University of Edinburgh to carry out an independent review of the Department’s work on BARB cases in the UK.

Professor Hill published his review in July 2005. Professor Hill’s review concludes that the UK controls in place to eliminate BSE in cattle are soundly based. The review confirms that the elimination of food-borne sources is key to the eradication of BSE. It recommends that risk-based controls and monitoring should be maintained on animals and feed. The report is available (177 KB) and the Defra response is available here (55KB).

Public Health

The main public health control is the removal of Specified Risk Material (SRM) in abattoirs. This removes over 99% of infectivity from any cattle infected with BSE. However, all healthy cattle aged over 30 months and all emergency slaughtered cattle aged over 24 months must be BSE tested with negative results before they can be sold for human consumption. In March 2005, the UK started culling and incinerating the cohorts of all BSE cases, where the cohort animals were born after July 1996. A cohort is defined as a group of bovine animals born 12 months either side of the BSE case, or reared with it in the first year of their lives. i.e. cattle potentially exposed to the same feed during the period of greatest susceptibility to BSE.

Multiple Cases and the South West Wales Cluster

Eleven herds in Great Britain have generated a total of 24 BARB cases. These include two triple BARB cases (Pembrokeshire and Wiltshire) and nine paired BARB cases (Cornwall, Devon, Dorset, Somerset, Shropshire, Ceredigion and Orkney). Most of these natal herds are located in South West/ West England or South West Wales. The historic management of two of the three Ceredigion paired BARB case herds is such that these two herds can be regarded together as generating one quadruple BARB case: the two natal herds, are based at two premises. The four BARBs were moved to a third premises at approximately 2-months of age for rearing as a single unit, and remained there until approximately 30-months of age, when they returned to their natal premises.

21/24 of the multiple cases succumbed to BSE in their natal herds. 19/24 of the multiple cases have been detected by active surveillance. At least 11/13 of the subsequent BARB cases were cohorts of the index cases. 6/13 of the subsequent BARB cases were detected through the cohort cull which commenced in March 2005.

These findings support a common feed source during the first 12 months of life in each of the affected herds. A statistical analysis of the number of multiple BARB cases, carried out in 2005, provides evidence that BARB cases do not all occur by chance.

There is also an epidemiologically significant cluster of 8 BARB cases born between 1 August 1997 and 31 July 1998 in South West Wales. These cases include the quadruple BARB case and one of the paired BARB cases, and all the animals received feed from two local feed mills.

In 2005, another herd in South West Wales experienced a BSE case born in October 2001. The subsequent cull of the cohorts of this case detected two further cases born in September 2001 and May 2002. Detailed epidemiological investigations of the herd of origin suggested that these three cases were the result of infected feed from a local mill retained in a feed bin. The feed bin had been in use for adult cattle since September 1998, but was moved and filled with calf rearer feed in late July 2002. One or more bulk consignments of imported feed contaminated with infective material, supplied in 1998/99 to several local feed mills, is believed to have produced the South Wales BARB clusters.

A report of the feed investigations into herds generating the cluster of BARB cases in South West Wales and into herds experiencing multiple BARB cases is available below:

• Report on Extended feed investigations into herds generating a cluster of BSE cases born after July 1996 in South West Wales & into herds experiencing multiple BSE cases born after July 1996. (112 KB);
• Appendix 1: UK BSE cases in animals born after the reinforced feed ban of 31 July 1996. (20 KB);
• Appendix 2: Details of multiple BARB BSE cases in Great Britain. (51 KB).

A full report of the epidemiological investigations into the three Pembrokeshire BARB cases born in 2001 and 2002 is available below:

• Final report on BSE confirmed in an animal born on 3 October 2001 & 2002 cohort animals born on 28 September 2001 & 1 May 2002 in Pembrokeshire herd. (56 KB).

Persistence of the BSE Agent in Feed Stores

There is evidence from the epidemiological investigations into the herds experiencing multiple BARB cases that some of these cases may have resulted from the persistence of infection in farm feed bins beyond the dates of the official feed ban. We believe that the current risk of BSE infection to cattle as a result of the persistence of the BSE agent in farm feed bins, from feed produced before either the 1996 UK feed ban or the 2001 EU feed ban, is extremely low. Nevertheless we recommend that cattle keepers clean out feed bins routinely and very thoroughly, particularly those feed bins which were in use before August 1996 and have not been cleaned out since. This is especially important for herds in the areas where herds have experienced multiple BARB cases, and any herds which have experienced homebred BSE cases. The design of many feed bins is such that specialist contractors and/or equipment may be required to minimise the health and safety risks of cleaning the inside of feed bins.

Position in Other Member States

The European Union imposed an EU-wide ban on the feeding of mammalian protein to ruminants in 1994, and an EU-wide ban on the feeding of processed animal protein (PAP) to all farmed animals from January 2001.

Most other EU Member States have experienced cases born in or after 1996. By the end of 2004, some Member States reported a higher prevalence of such cases (cases per million adult cattle) than the UK.

Some EU Member States have also had one or more BSE cases confirmed in cattle born in 2000, 2001 and 2002.

Page last modified: 3 October, 2008
Page last reviewed: 10 September, 2006

Top of the page