Vet. Res. 38 (2007) 505-516
DOI: 10.1051/vetres:2007011

Case-control study on feed risk factors for BSE cases born after the feed ban in France

Nathalie Jarrige^a, Christian Ducrot^b, Géraldine Cazeau^a, Eric Morignat^a, Claude La Bonnardière^c and Didier Calavas<sup>a

a</sup>  Unité Épidémiologie, AFSSA Lyon, 31 avenue Tony Garnier, 69364 Lyon Cedex 07, France
^b  Unité d'Épidémiologie Animale, UR346, INRA, Centre de Theix, 63122 Saint-Genès-Champanelle, France
^c  Unité de Virologie et Immunologie Moléculaires, UR892, INRA, Centre de Jouy-en-Josas, 78350 Jouy-en-Josas, France

(Received 7 July 2006; accepted 5 January 2007 ; published online 11 April 2007)

Abstract - In France, after the ban on meat and bone meal (MBM) in cattle feeding in June 1990, cases of Bovine Spongiform Encephalopathy (BSE) have continued to be detected in bovines born after that ban (called BAB cases). A case-control study was therefore carried out to determine the way these cases were contaminated. A multivariate conditional model was built adjusting for the production type of the animals and taking into account the herd size. The results confirmed that feeding cattle with proprietary concentrates was at risk for BSE, with an adjusted odds ratio of 6.8 (2.5; 18.7) for the consumption of less or three different proprietary concentrates and 17.6 (5.7; 54.8) for more than three, when comparing with no consumption of proprietary concentrates, considering feeding of bovines before the age of two. The results suggest that cross-contaminations by MBM in bovine concentrates have occurred after 1990. To a lesser extent, on-farm cross-contaminations, i.e. consumption by cattle of feedstuffs initially dedicated to other animals and which could legally contain MBM, have probably also existed, since the presence on farms of poultry fed purchased feed involved an increased risk of BSE with an odds ratio of 1.8 (1.1; 3.0). The use of milk replacers, which often incorporates animal fats, was also at risk with an odds ratio of 1.8 (1.0; 3.1).

Key words: BSE / cross-contamination / cattle feeding / proprietary concentrates / France

Corresponding author: n.jarrige@lyon.afssa.fr

© INRA, EDP Sciences 2007