Information released on 20 July 2005

Summary of information requested
Details of the 1992 experiment described in section 92, volume 1 of the 'BSE Inquiry and Conclusions' where a single quantity of infective material weighing 1 gram was fed to cattle which then developed BSE. In particular, who carried out these experiments, how many cattle were infected, what quantity of material was fed to the other cattle and how many cattle developed BSE.

Details of the results from a separate trial carried out in 1998 at Drayton Research Centre with 300 steer cattle which was due to last five years.

Information released
The 1992 experiment in question is referred to in the BSE inquiry (MAFF/Defra project code SE1918). This study is commonly called the 'Attack Rate Study'.

In this experiment 40 calves, aged approximately four months of age, were orally challenged with BSE infected brain homogenate. The calves came from BSE-free herds.

The study is summarised below. An interim report on this study is on target to be published in 2006.

Attack Rate Study
Oral dose given Number that died of BSE/ number of calves in the group
300g (as three doses of 100g) 10/10
100g 10/10
10g 7/10
1g 7/10

The project is also briefly mentioned in the European Commission Report 'Update of the opinion on TSE infectivity distribution in ruminant tissues' (Section 111.1.1).

Trials started in 1998 at Drayton (MAFF/Defra project code SE1736). The study intended to provide material from both live and dead animals to enable the evaluation of potential diagnostic tests. As such it is not in itself a publishable experiment.

This study involved 100 (90 steers and 10 heifers) calves infected with 100g of BSE positive brain material, 100 infected with 1g and 100 unexposed animals. Materials from this study is stored at the VLA (TSE Archive), and distributed to research groups around the world.

Approximately 20 live animals remain in the study, these being the few females that were put to calf to enable the collection of milk.

Further information