1a.Objectives (from AD-416)
The objective of this study is to evaluate the effectiveness of feeding heat-treated colostrum to calves in herds infected with Mycobacterium avium subsp. paratuberculosis (MAP). Since MAP is shed into the milk of infected dams, feeding colostrum from naturally infected dams can be a potential source for transmission of infection to neonatal calves. Pasteurization has proven effective in the destruction of viable MAP in colostrum and waste milk on-farm. However, little is known about the long-term effects of feeding pasteurized colostrum on the general health of the calf. Even less data are available documenting effects of feeding pasteurized colostrum on MAP infection in calves. We will receive colostrum samples from naturally infected dams from each of the selected herds within the study and determine the presence of MAP within the samples in order to evaluate the potential exposure of the neonates to the bacterium.
1b.Approach (from AD-416)
Colostrum samples will be collected on the day of calving from cows on the study. Up to 600 colostrum samples will be frozen and shipped on ice to the NADC for processing. DNA will be extracted from the colostrum samples by a standard protocol used in the laboratory and then RT-PCR will be performed for the identification of a unique target gene for MAP (ISMap02). The RT-PCR method will include the use of a probe and a standard curve generated by a plasmid control that will allow for semi-quantitation of the MAP bacterium in the colostrum. The goal of the study is to identify colostrum samples that are positive for the MAP bacterium and utilize this information to determine if heat-treatment of colostrum will reduce the risk of transmission of MAP infection to neonatal calves.
This collaborative research project between ARS, the National Animal Disease Center (NADC) and the University of Minnesota encompasses measures to ensure animal health through the control and management of the disease by improving our understanding of the infection process for neonatal calves. Morbidity and mortality in neonatal calves is a major concern for dairy producers. Evidence suggests that calves can become infected shortly after birth by exposure to pathogens such as MAP, Salmonella, and Mycoplasma in either the feces or milk of infected dams, bedding or cohabitation with other infected animals. These pathogens may be spread to calves through colostrum from sick or infected cows. Some producers have opted to feed colostrum replacers to their calves to avoid the potential spread of disease. However, this is an additional expense that some producers cannot afford. Pasteurization of colostrum is an economical alternative to commercial colostrums products, however, little is known about its effectiveness in destroying pathogens or on the immunoglobulin content. This project has the specific objective to evaluate the effectiveness of feeding heat-treated colostrum to calves in herds infected with Mycobacterium avium subsp. paratuberculosis (MAP) on the general health of the calf and on the incidence of paratuberculosis in the herd. Approximately 200 of the 600 samples have been collected and received by the NADC for processing. DNA extraction and RT-PCR analyses for these samples has been completed and data records have been sent to the collaborator. In addition, further validation of the methodology was demonstrated in a blinded study designed to evaluate the sensitivity and specificity of the technique as well reproducibility in 2 laboratories. This information provides a useful management tool for dairy producers in allaying the spread of infectious disease to their calves and improving their health. Progress will be monitored by the associated parties via phone calls, e-mails and/or meetings every 2-3 months.