4d.Progress report.
This report serves to document research conducted under a specific cooperative agreement between ARS and the RGA’s Veterinary Service. Additional details of research can be found in the report for the parent project plan 0210-22310-002-00D, International Cooperative Programs. Dairy production in the Azores represents one of the largest sectors of the economy; producers need to continue increased production trends and expansion of markets for Azorean dairy products, as called for under the 1995 Agreement on Cooperation and Defense between the United States and Portugal. The RGA’s veterinary service and University of Azores, with technical support from USDA, seek to mitigate problems in the Azorean dairy production system by establishing a health monitoring system of the herd, extension programs for farmers on dairy and human health issues related to milk production and a common research agenda in bovine genomics related to disease resistance. Investigators conducted an epidemiological study to determine the prevalence of dairy herds in Terceira island, Azores – Portugal, with positive antibody levels of Bovine Viral Diarrhoea Virus (BVDV), of Bovine Herpesvirus 1 (BHV.
1)and of Neospora caninum, and investigate the significance of the associations between the level of antibodies and herd size. Antibodies from the mentioned agents were detected and quantified through the enzyme-linked immunosorbent assay (ELISA) in bulk milk samples from 799 herds, totalling 21,178 dairy cows. A structured survey of the milk herders was made to collect relevant data to interpret the results achieved by this study. The prevalence of herds with BVDV, Neospora caninum and BHV 1 positive antibody levels was respectively 97%, 64% and 55%, showing a high exposure to the mentioned infectious agents. An analysis of the geographical locations of the dairy herds with positive antibody levels confirmed that these are distributed quite homogenously around the whole island. The high occurrence of co-infections between BVDV, BHV 1 and Neospora caninum was confirmed. The proportion of herds with antibodies from the three agents simultaneously were detected higher (P < 0.05) than the proportion of herds with only one or two of the infectious agents detected, about 35.7%. Herd size was not associated with the level of antibodies in bulk milk samples (P > 0.05).