Volume 5: Animal Health, 1989-96
2. The ruminant feed ban, 1989-96
The chronological account
The period prior to the identification of the first BAB

The period prior to the identification of the first BAB

Development of the ELISA test

2.51 As discussed earlier in paragraphs 2.14-2.15, at the time when the RFB was under consideration, there was concern within MAFF that it would not be enforceable in the absence of a reliable test to detect ruminant protein in animal feedstuffs. It was hoped that a test would become available soon after the RFB came into force. The Enzyme Linked ImmunoSorbent Assay (ELISA) test was a technique subsequently developed to detect ruminant protein in feedstuffs. The underlying technique of the test is discussed in vol. 2: Science. In this chapter we explain the development of the test and the effect its delay had on the RFB's development.

2.52 On 15 January 1989 Dr Richard Cawthorne, Head of Veterinary Investigation Section at Tolworth, minuted Dr Peter Dawson, Head of Veterinary Investigation Service, to update him on the progress of techniques to detect animal protein in feedstuffs. He explained that the ELISA test had been developed at the Agriculture and Food Research Council (AFRC) Meat Research Institute in Bristol, and that following two meetings in the second half of 1988, 'AFRC have been appraised of MAFF's needs and collaborative development work has continued on the development of the ELISA technique'. There were still a number of problems to be resolved, such that it was not 'presently well enough advanced to be of routine diagnostic value'. Dr Cawthorne thus presented two options. If the need for the test was urgent, MAFF could work with AFRC to produce a commercial package. This would be costly, but a test could be available within three to four months. However, AFRC would retain intellectual property rights to the work and MAFF would have to purchase the test kit from AFRC. Alternatively, MAFF could initiate its own programme of research and development at Worcester VIC. It was estimated that this work would take between 12 and 18 months. Dr Cawthorne said that the necessary equipment, facilities and expertise were available. ¹

2.53 By 21 February 1989 Mr Meldrum had elected to develop an ELISA test within MAFF, with Mr Mike Ansfield, a Senior Scientific Officer at Worcester Veterinary Investigation Centre (VIC), leading the project. ² In a statement to the Inquiry, Mr Meldrum said that this was due to 'Redundancies at the AFRC and other difficulties'. ³

2.54 Mr Ansfield prepared a project proposal with a development work timetable, which was forwarded to Dr Cawthorne on 6 April 1989. It was anticipated that by December 1989 MAFF would have available 'a technique or techniques that will give maximum sensitivity to antigens in processed protein within the limitations of the antisera provided'. ⁴

2.55 In a statement to the Inquiry, Mr Ansfield said it was explained to him that the:

. . . purpose of the work was to find a method for the detection of species of ruminant origin in processed material for animals because of the increased incidence of BSE at that time. ⁵

2.56 On 21 July 1989 Mr Ansfield informed Mr Allsup, Senior Veterinary Investigation Officer at Worcester VIC, that Mr A R Hunter, Deputy Regional Veterinary Officer, had told him over the telephone that Mr Meldrum was 'inquiring of the stage of the BSE project, and that he wanted the results "yesterday"'. Mr Ansfield told Mr Hunter that the project was going to plan. ⁶

2.57 Mr Ansfield provided progress reports to Mr Allsup on 21 August and 29 September 1989, describing various aspects of the project work. Neither of the reports mentioned any significant problems or delays. ⁷

2.58 The first problem with the ELISA test was raised following the 29 September report, when difficulties were encountered with the extraction of gelatine from feed. Mr Ansfield explained to Mr Allsup the avenues that were being pursued to overcome this problem on 13 November 1989. ⁸ Mr Ansfield reported on 17 January 1990 that progress was being made in overcoming the obstacles. ⁹

2.59 Mr Ansfield said in a statement to the Inquiry that:

I do not recall, during the early development of this test, receiving any written communication declaring the urgency or priority of the task, but my telephone conversations with Mr A R Hunter and occasionally Dr R Cawthorne gave credence to the importance of the work . . . ¹⁰

Dissemination of information

2.60 MAFF issued a Food Facts leaflet on 9 January 1990 entitled, 'Government Action on BSE'. It listed 'wide-ranging measures' taken by the Government, including the ruminant feed ban (RFB). It noted:

The use of ruminant-based protein as food for cattle, sheep and other ruminants was banned from 18 July 1988. Research shows this to be the most likely cause of BSE.

There is no scientific justification to extend the ruminant food ban to pigs and poultry. The Southwood Report acknowledged the importance of the feed ban for ruminants, but did not recommend that it be extended to pigs and poultry. ¹¹

2.61 By early March 1990 MAFF had begun work on an advisory leaflet on BSE to be distributed to farmers. ¹² A draft of this leaflet, entitled, 'Bovine Spongiform Encephalopathy (BSE): Advisory Notes for farmers', was submitted to Mr John Gummer, the Minister of Agriculture, on 11 April 1990. He decided that it should be submitted to SEAC for comment. ¹³ In the event, at its meeting on 1 May 1990, SEAC's attention was directed to the leaflet's advice on breeding from the offspring of affected cattle (see Chapter 6 and vol. 11: Scientists After Southwood), and it therefore did not consider the leaflet's content about the RFB. ¹⁴

2.62 Also in May, a draft 'Leaflet for Consumers' was circulated within MAFF and sent to the Department of Health (DH) for consultation. It summarised the Government's knowledge of BSE and the action taken. It concluded:

The most likely cause of BSE was the feeding to cattle of compound rations which contained protein material derived from sheep, some of which were infected with scrapie.

The practice of feeding ruminant protein to ruminants, including cattle, sheep and deer, was banned in July 1988 so the source has been cut off. ¹⁵

2.63 Mr Gummer sent this advice by letter to Lady Wilcox, Chair of the National Consumer Council. He hoped that Lady Wilcox would bring the advice to the attention of interested organisations, and informed her that he would be releasing the text of the letter to the press. ¹⁶

2.64 MAFF's Advisory Note to farmers was released in June 1990. It stated:

Scrapie infected sheep are thought to be the origin of BSE, not by direct contact on the farm but, most probably through the feeding of contaminated meat-and-bone meal. Since then, BSE infected material will also have passed through the rendering system, allowing recycling of the disease to cattle.

The use of ruminant protein (ie from animals such as sheep, cattle, and deer) in ruminant diets was banned in July 1988 to cut off this source of transmission. ¹⁷

2.65 On the future of the disease the Advisory Note recorded:

Cutting off the main source of infection to cattle through feed should cause the number of reported cases to fall from 1992/3 - in other words some 4 years after the introduction of the feed ban. Much will depend on whether or not infection can spread from cow to calf, or more importantly from animal to animal (cow to cow, calf to calf). At the time of writing it is still too early to detect evidence of such spread because all cases reported so far will potentially have had access to contaminated feed. ¹⁸

Dose

2.66 Mr John Wilesmith, Head of the CVL's Epidemiology Department, attended a UKASTA meeting on BSE on 10 April 1990, where he provided an update on the BSE epidemic. Various BSE issues were discussed. He advised that the CVL was 'totally satisfied' that the feeding of infected MBM was the cause of BSE. Mr Wilesmith also outlined points of epidemiological interest and noted that it 'was also considered that the higher the dose the shorter the incubation period' (see vol. 3: The Early Years, 1986-88 for discussion on early perceptions about infective dose). ¹⁹

Rumoured UKASTA ban on all meat and bone meal

2.67 On 22 May 1990 Mr Hill, Private Secretary to Mr David Maclean, Parliamentary Secretary, minuted Mr Gummer about a conversation he had with Mr Bob Harrison of UKRA. Mr Harrison informed Mr Hill that he believed UKASTA intended to exclude all MBM from animal feed as from 1 June 1990. Mr Hill had asked Mr Lowson to 'confirm the rumours and to advise on the next step'. ²⁰

2.68 Mr Lebrecht, Principal Private Secretary to Mr Gummer, replied on the same day that if the rumour was confirmed, Mr Gummer would like Mr Maclean 'to take the matter up with UKASTA and try to steer them off this course'. ²¹

2.69 In the event, Mr Lowson's investigations revealed that UKASTA had not changed its position. Their advice to members remained that they should not incorporate MBM that contained specified bovine offal (SBO) in their feed. ²²

Further work on the ELISA test

2.70 Meanwhile, work on the development of the ELISA test continued. On 3 April 1990 Mr Ansfield reported to Mr Allsup that sample extraction was at the 'next stage of development', using the gelatine extraction processes he had previously described. ²³

2.71 Mr Ansfield provided a full update for Dr Cawthorne on 24 May 1990. He predicted that:

If the concentration procedure is successful I will be able to assess the most suitable immunoassay within a month to six weeks.

I have discussed validation times with the CVL, Weybridge and in their opinion validation of ELISA, which I expect to be the most sensitive assay, will take at least to the end of the year. This time includes a period at the CVL which would be essential to expediate validation. ²⁴

2.72 The use of commercially available meat species identification kits was a possibility considered at various points in the development of the ELISA test. Early in 1990 Mr Ansfield had tested one such kit, but it was incapable of detecting meat species in material cooked for 40 minutes at 121ºC. The producers of the kit informed Mr Ansfield that an improved version would soon be available, and on 19 June 1990 Mr Ansfield sought Mr Hunter's approval to purchase and test the new kit. The aim of the testing would be to establish its detection limits. Mr Ansfield advised that 'I will be looking at our own antisera with a view to perfecting our own immuno-assay by the end of the year'. ²⁵

2.73 During oral evidence, Dr Brian Cooke confirmed that the kit Mr Ansfield had tested was of limited value. He stated that it gave 'an awful lot of false results; and we rapidly concluded that we could put no reliance on it whatsoever'. ²⁶

Report of the Agriculture Select Committee

2.74 The House of Commons Agriculture Select Committee decided on 16 May 1990 to undertake an inquiry into BSE, 'to gather the relevant evidence and present the House with an early assessment of the available facts'. ²⁷

2.75 Mr Gummer gave evidence to the Committee on 23 May 1990. He assured them that MAFF had a continuing programme looking at ways in which it could improve the control of animal feedstuffs. He said:

[W]hat we did was in advance of the knowledge being there we did the ban on feeding ruminant animal protein to ruminants which I believed to be right. I have a natural sympathy with the argument that there is something odd about that and something which we should not follow, although it is perfectly true that many animals have been fed animal protein for centuries, going back to the Romans, but not cows in these circumstances and that is why we stopped it. ²⁸

2.76 Mr Raymond Bradley, Coordinator of BSE research at the CVL, gave evidence to the Committee on behalf of the CVL, noting that:

. . . since the ruminant feed ban in 1988, and having removed the source of infection, the infectivity rate of cattle is now falling down in an equivalent fashion to how the epidemic was rising at an earlier point in its course. Thus animals which were born after July 1988 are in fact coming into the slaughterhouse now as prime-beef animals. These animals will not have been fed the incriminated protein, thus infection or infectivity within them will be absent. We have to concede there are the possibilities of maternal transmission . . . ²⁹

2.77 In its report, which was published on 10 July 1990, the Agriculture Select Committee said:

The most obvious loopholes have already been closed. Since 18 July 1988, the feeding of animal protein derived from ruminants to cattle and other ruminant animals has been prohibited under the Bovine Spongiform Encephalopathy Order 1988. This legislation, if strictly applied, should arrest the presumed cause of the disease in cattle: cases will continue to be reported because of the disease's prolonged incubation period. ³⁰

2.78 The Agriculture Select Committee recommended that the Government establish an expert committee to examine the whole range of animal feeds and advise how the industries that produced them should be regulated. ³¹ The Lamming Committee was subsequently established in early 1991 (see paragraph 2.143).

MAFF issues instructions to the SVS in the event that BABs are discovered

2.79 On 5 July 1990 Mr Wilesmith met Dr Cooke and Miss Judith Nelson of UKASTA's Feed Committee, to discuss various BSE issues. It was noted that the RFB would have been in operation for two years on 18 July 1990. However, it was estimated that actual feeding of ruminant derived protein to ruminants would have effectively stopped two months after the date of the ban, after farmers had used up existing supplies. It was noted that the youngest animal to have been identified with BSE was 22 months of age. The note of the meeting recorded that:

If it were now to be diagnosed in such young animals it would mean that the disease could be transmitted by means other than through animal feedingstuffs. ³²

2.80 Animal Health Circular 90/58 was issued on 20 July 1990. It instructed veterinary officers (VOs) that when giving details of suspect BSE cases, they should draw attention to any animal born after 18 July 1988. VOs were also to record details of each animal's dam, such as breed, age, origin (homebred or purchased), present whereabouts (still in herd or sold elsewhere), whether still alive and whether the dam was ever a suspect or confirmed BSE case. ³³

2.81 Mr Wilesmith explained in a statement to the Inquiry that these measures 'enabled us to make an initial assessment of the risk of maternal transmission and, following the complete pathological examination, to determine whether there was any change in the pattern of lesion distribution which could be indicative of a different route of infection'. ³⁴

The Bovine Spongiform Encephalopathy (No. 2) Amendment Order 1990

2.82 The Bovine Spongiform Encephalopathy (No. 2) Amendment Order 1990 (the Order) introduced the animal SBO ban on 25 September 1990. ³⁵ The purpose of this ban was to extend the prohibition on the use of SBO from human food to feed intended for all animals and poultry (see Chapters 3 and 4).

2.83 The animal SBO ban was introduced by an amendment to article 8 of the Bovine Spongiform Encephalopathy (No. 2) Order 1988, which implemented the ruminant feed ban. The new article 8 provided:

(1) No person shall knowingly sell or supply for feeding to ruminating animals any feedingstuff in which he knows or has reason to suspect any animal protein has been incorporated.

(2) Subject to paragraph (5) below, no person shall feed to a ruminating animal any feedingstuff in which he knows or has reason to suspect that any animal protein has been incorporated.

(3) No person shall knowingly sell or supply for feeding to animals or poultry any specified bovine offal or any feedingstuff which he knows or has reason to suspect contains specified bovine offal or animal protein which is derived from any specified bovine offal.

(4) Subject to paragraph (5) below, no person shall feed to an animal or poultry any specified bovine offal or any feedingstuff which he knows or has reason to suspect contains specified bovine offal or animal protein which is derived from any specified bovine offal.

(5) The prohibitions in paragraphs (2) and (4) above shall not apply to the feeding of specified bovine offal or a feedingstuff to an animal or poultry for research purposes under the authority of a licence issued by a veterinary inspector and in accordance with any conditions subject to which the license is issued. ³⁶

2.84 The first two paragraphs retained the ruminant feed ban, and the second two introduced the new animal SBO ban (see Chapters 3 and 4). However, to accommodate the animal SBO provisions, the definition of 'animals' was extended from ruminating animals to 'any kind of mammal except man, and any kind of four footed beast which is not a mammal'. ³⁷

2.85 'Animal protein' was defined in the Order as any protein material derived from a 'carcase'. For the purposes of 'animal protein', 'carcase' meant the carcass, or part of the carcass, of an 'animal'. Therefore, the new Order had the unintended effect of extending the ruminant feed ban to ban the feeding of any animal protein to ruminants.

2.86 As explained in a note prepared by the Animal Health and Veterinary Group for the Lamming Committee, this oversight had little practical consequence. This was because no rendering plant was producing MBM for incorporation into ruminant feeds. ³⁸ Nevertheless, this error was subsequently amended. ³⁹

2.87 The introduction of the animal SBO ban had further relevance to the RFB. Before its introduction, compounders could legitimately include protein derived from SBOs in animal feed for non-ruminants (mainly pigs and poultry). Many feedmills produced such feed using the same lines as those used to manufacture feed for ruminants, with an associated risk of cross-contamination. Mr Meldrum noted that:

Therefore, the protection of cattle and other ruminants from the agent of BSE was firstly afforded by the ruminant protein ban of 18th July, 1988 and, secondly, by the SBO ban of September 1990. ⁴⁰

ELISA test progress

2.88 On 1 November 1990 Mr Ansfield reported to Mr Allsup 'considerable progress' on the development of the ELISA test. The test was capable of detecting extracts from bovine and ovine material at a dilution of 1/400, which was 'a sensitivity far greater than the current commercial kit available'. Further 'fine tuning' was required, but the test was not cross-reacting with other species, so was specific to ruminant protein. The test could not distinguish between bovine and ovine material and work so far suggested that this would not be possible. Mr Ansfield said that he felt 'confident that validation will be carried out before the end of the year and the test will then be available for use'. ⁴¹ Dr Cawthorne relayed this information to Mr Meldrum on 8 November 1990. Mr Meldrum told Dr Cawthorne that he should 'keep up the pressure to obtain validation by the end of this year'. ⁴²

UKASTA's concerns about cross-contamination

2.89 According to Mr Meldrum, when the RFB was introduced MAFF did not foresee that cross-contamination in feedmills could pose practical difficulties - see vol. 3: The Early Years, 1986-88 for a discussion on whether cross-contamination was foreseen. In a statement to the Inquiry, he pointed out that cross-contamination was not an issue raised by industry representatives during meetings to discuss the proposed feed ban in 1988. Further, given the knowledge that some cross-contamination could occur at feedmills and given the views on infective dose expressed by Mr Wilesmith (see paragraph 2.66):

. . . if I, or indeed any of the other MAFF or industry representatives, had known at that time that the infective dose was really so low as to lead to cross-contamination problems, the issue would have been pursued, as indeed it was at a later stage as a result of the investigations into BABs and the use of the ELISA test in the field. ⁴³

2.90 A note of a meeting with the cattle industry on 28 June 1988 records Mr Meldrum as saying that 'feed compounding mills presented, at worst, only a low contamination risk'. ⁴⁴

2.91 However, MAFF's attention was drawn to cross-contamination in feedmills when Dr Danny Matthews, SVO in the Notifiable Diseases Section, attended a meeting of the UKASTA Scientific Committee on 14 November 1990 to discuss a number of BSE issues. Various questions were put to him. In response to a question on genetic susceptibility, the note of the meeting records:

It was considered that the BSE agent had adapted to the host and not that the host had changed to become more susceptible to the agent. There was no change in the cattle; the change had been in the challenge, i.e the dosage rate of the infected material which would have increased over the past few years. A dose-related response had been seen; the bigger the dose the greater the chance of BSE developing. ⁴⁵

2.92 On the issue of cross-contamination, the note of the meeting records:

UKASTA pointed out that, with the use of special detection kits, Trading Standards Officers could detect very low levels of meat and bonemeal in ruminant rations because of either the possibility of cross-contamination in the feed mill or because traces could be present in tallow which was still permitted for use in ruminant rations. Compounders could, therefore, be faced with the possibility of prosecution by Trading Standards Officers. Also, if a compounder sold a dairy feed to a farmer who subsequently had a case of BSE and traces of ruminant animal protein were found in the feedingstuff a court could find the compounder legally responsible. In the light of these considerations, compounders might feel that they had no option but to review their policy on the use of meat and bone meal altogether. ⁴⁶

2.93 It was concluded that:

Mr Meldrum should be made aware of the concern arising from possible cases of cross-contamination of a dairy feed with small traces of monogastric ration and/or the detection of meat and bonemeal in tallow used in ruminant feedingstuffs. ⁴⁷

2.94 Accordingly, on 15 November 1990 Dr Matthews reported the outcome of the meeting to Mr Meldrum, and highlighted UKASTA's concern about cross-contamination:

. . . knowing that there will always be some risk of cross contamination at the mill, for whatever reason and usually only in trace amounts, they fear that they will be accused by cattle owners of introducing disease . . . In addition, Trading Standards officers around the country have been showing increasing interest in their practices. They therefore fear that use will be made of developing ELISA techniques to detect small amounts of ruminant contaminant in feed for ruminants, leading eventually to prosecution. ⁴⁸

2.95 Dr Matthews explained the concern about cross-contamination in a statement to the Inquiry:

References . . . to cross-contamination relates to the concerns of feed manufacturers that a sensitive test to look for evidence of contamination with ruminant protein might be capable of detecting trace amounts of protein that they might only be able to prevent by the total exclusion of meat and bone meal from all their products. At this time the purpose of the development of the ELISA Test was to assist in enforcing the Ruminant Feed Ban. I do not recall any concerns within MAFF at that time that cross contamination of feed was or might be taking place such as to undermine the effectiveness of the Ruminant Feed Ban. ⁴⁹

2.96 Dr Matthews further explained his difficulty in establishing when MAFF first became concerned about cross-contamination:

I was not party to all discussions amongst senior officials, and in other parts of MAFF, on many aspects of BSE policy. I can therefore only report on issues of which I have personal knowledge. I regret that I cannot therefore identify with any precision when MAFF or myself first became concerned about the issue of cross-contamination. I have equal difficulty in identifying with any precision when I "first became concerned" that relevant cross-contamination might have occurred. The impression given from the questions posed is that such concern may have occurred as a single event, but I believe that . . . the process was one of gradually increasing concern as alternative routes of exposure were eliminated. ⁵⁰

ELISA test produces 'accurate and reproducible results'

2.97 On 14 December 1990 Mr Ansfield informed Mr Allsup that minor changes had been made to the ELISA test and that it produced 'accurate and reproducible results'. He said:

I therefore confirm that the sandwich ELISA for speciation of animal species in processed meal incorporating a concentration procedure can detect ruminant protein at a minimum concentration of 1 in 200 for ovine and 1 in 400 for bovine. ⁵¹

2.98 MAFF now had a test that could accurately detect bovine and ovine material in MBM. It still needed to assess whether the ELISA test could accurately detect these amongst the multitude of other ingredients within compound feed, which was the finished product ultimately fed to cattle. Mr Hunter asked Mr Ansfield to carry out this work, and on 24 January 1991 Mr Ansfield told Mr Winkler, SVO at Worcester VIC, that he had obtained 27 different compound feeds for this purpose. He advised that it was his 'intention over the next 2-3 months' to incorporate MBM and then test the samples and ascertain limits of detection for bovine and ovine material. ⁵²