Volume 5: Animal Health, 1989-96
6. Breeding
Early consideration of cattle breeding and BSE
MAFF's advice to veterinary surgeons
The Southwood Working Party consider maternal transmission
The Tyrrell Consultative Committee's recommendation

6.6 As part of its efforts to learn more about BSE, MAFF was concerned to determine the routes by which it might be transmitted. A number of different experiments were planned to test whether BSE could be transmitted maternally. These included (see vol. 2: Science for discussion of the experiments):

1. analysis of pedigree data;
2. long-term cohort study;
3. embryo transfer study; and
4. infectivity of placenta, intestine and milk.

6.7 However, as MAFF informed various breeding industry representatives during a meeting on 13 July 1987, 'research is being undertaken into the transmissibility of the condition although because of the nature of the problem it is unlikely that any results would be available in the short term'. ¹ Indeed, results were not anticipated for several years. In the meantime, however, MAFF was under pressure to provide advice to veterinarians and farmers on breeding in light of BSE.

MAFF's advice to veterinary surgeons

6.8 On 14 April 1988, during a Minister's meeting on BSE, it was agreed that BSE should continue to be handled in a low profile manner. It was decided that a short article should appear in the Veterinary Record. ² In his written answer to a Parliamentary Question on 28 April 1988, Mr Donald Thompson, the Parliamentary Secretary (Commons), stated that farmers and veterinarians were receiving advice, based on the current state of knowledge about the disease, via Veterinary Investigation Centres (VICs). He said that the latest advice would appear in that week's Veterinary Record. ³

6.9 A short article entitled 'Ministry sets up BSE study and issues advice' appeared in the Veterinary Record on 30 April 1988, announcing the establishment of the Southwood Working Party (see vol. 4: The Southwood Working Party, 1988-89), and setting out MAFF advice on BSE. On breeding, it advised:

In the light of experiences with possibly similar diseases in other animals and in the present state of knowledge on BSE it is recommended that the progeny of affected cows should not be retained for breeding purposes. ⁴

6.10 The status of this advice is not clear. Its appearance in the Veterinary Record suggests that MAFF intended it to be advice to veterinary practitioners, rather than advice to farmers. However, there was no reference to the advice when MAFF officials contemplated issuing similar advice to farmers in 1990. The practical impact of this advice is similarly unclear. During oral evidence, some farmers said that despite being aware of the Veterinary Record advice, they continued to breed from the offspring of affected cows, with no subsequent problems in their progeny. Other farmers said they were not aware of the advice. ⁵ However, in a memorandum submitted to the Agriculture Select Committee in June 1990, the British Veterinary Association (BVA) stated that 'we have no doubt that many prudent livestock farmers have avoided breeding from the infected lines - this is the advice they have been given by their veterinary surgeons'. ⁶

The Southwood Working Party consider maternal transmission

6.11 The Southwood Working Party's Report was published in February 1989. See vol. 4: The Southwood Working Party, 1988-89 for a full account of the Working Party's work. In its report, the Working Party qualified its estimations of future infections in cattle by saying:

No allowance has been made either for new infections arising from maternal transmission: insufficient time has elapsed to determine whether maternal transmission occurs in BSE and if so at what incidence. Given the age distribution of the BSE cases at the onset of clinical signs and therefore the number of offspring which survive the minimum incubation period, the occurrence of maternal transmission, should it occur, is unlikely to be witnessed until 1990.

Though maternal transmission would increase the number of cases on its own it would probably be insufficient to sustain BSE in the national cattle population because it is likely that the number of offspring per case which will reach a susceptible age and produce their own offspring will be less than one. ⁷

6.12 Although the Working Party urged that all necessary resources be made available to allow the successful completion of maternal transmission studies already underway, it did not make any recommendation on breeding from the progeny of BSE-affected animals. ⁸

The Tyrrell Consultative Committee's recommendation

6.13 The Tyrrell Consultative Committee on Research was established to advise MAFF and the Department of Health (DH) on needs and priorities in research on transmissible spongiform encephalopathies (see vol. 11: Scientists after Southwood for a full account of its work). It presented an Interim Report to MAFF and DH in June 1989, which was published in February 1990.

6.14 In its report, the Committee noted that 'knowledge about whether or not maternal transmission can take place is essential for the agricultural industry and for users of its products, such as the manufacturers of biological pharmaceuticals'. It therefore gave a formal controlled study on possible vertical transmission the highest research priority. ⁹