On each occasion sampled cows were between 7 days before their predicted calving date and 42 days after calving (as sampling was also used to study metabolic parameters in peri-parturient cows; Fall et al., in press). (HRSV), is an enveloped, negative-stranded RNA computer virus classified in the genus of the family (Stott and Taylor, 1985). Although it is a major cause of respiratory disease in young calves and has a considerable economic impact (Van der Poel et al., 1994, Valarcher and Taylor, 2007), cattle of all ages can be infected with BRSV, and severe morbidity and mortality has been explained in adult animals (Elvander, 1996). Outbreaks of these viral infections usually occur in the autumn and winter months and a humoral immune response persists for at least a 12 months following natural or experimental contamination. Epidemiological and experimental studies suggest that antibody levels correlate with immunity (Alenius et al., 1991, Schrijver et al., 1996, Tr?vn et al., 2001). Both BRSV and BCV facilitate secondary pulmonary bacterial infection, which typically necessitates considerable antibiotic use (H?gglund et al., 2007). One of the aims of organic farming is usually to reduce the use of antibiotics through the provision of optimal husbandry, nutrition and biosecurity but it is currently unclear whether organic management is more successful than conventional management Rabbit polyclonal to YSA1H in reducing the risk or prevalence of herd contamination with these viruses. This study set out to compare the JDTic serological prevalence of BCV and BRSV contamination in dairy cows managed under organic and standard management systems and to investigate potential risk factors associated with these infections. Materials and methods Selection of herds and animals Determined herds experienced more than 40 cows, were enrolled in the Swedish Standard Milk Recording Plan (SOMRS) and were located in the Uppland, S?dermanland, ?sterg?tland, and Sm?land regions of South-East Sweden. Selected organically managed herds experienced produced milk in accordance with organic requirements for at least 2 years previous to the study. Of the 52 eligible organic farms, 24 were willing to participate and, of these, 20 were randomly selected. Of the 156 eligible conventionally-managed farms, 32 agreed to participate and 20 were randomly selected. All 40 study herds were free of bovine viral diarrhoea virus (BVDV) as defined by The National Control Program (Lindberg and Alenius, 1999). All 40 herds were visited on two occasions C in the Spring of 2005 and 2006. On each occasion JDTic sampled cows were between 7 days before their predicted calving date and 42 days after calving (as sampling was also used to study metabolic parameters in peri-parturient cows; Fall et al., in press). If the number of such animals in a herd was 12, all were sampled. If the herd contained 12 eligible animals, 12 were randomly selected for sampling using a random number table. A total of 699 serum samples were taken from 624 cows in the 40 herds. At the 2005 sampling, 169 cows were sampled on conventional farms and 169 on the organic farms. At the 2006 sampling, 189 animals were sampled in the conventional herds and 172 in the organic herds. By chance 75 cows were sampled at both sampling times. Herd and animal data were collected via the SOMRS system and from farmer questionnaires at each sampling time. Data relating to diseases that required veterinary intervention on these premises were retrieved from the national animal disease recording database. Sample collection and antibody testing Blood JDTic sampling was via the tail vein into 10?mL Vacutainers without anticoagulant. Samples were transported at room temperature within 4?h to a laboratory where they were centrifuged at 2000for 10?min to produce serum and were then stored at ?20?C. All sera were tested using commercially available indirect.