Author
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Stabel, Judith |
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Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/31/2008 Publication Date: 9/1/2008 Citation: Stabel, J.R. 2008. Pasteurization of Colostrum Reduces the Incidence of Paratuberculosis in Neonatal Dairy Calves. Journal of Dairy Science. 91(9):3600-3606. Interpretive Summary: 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 Mycobacteriuma avium subsp. paratuberculosis, 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 colostrums 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 whether it prevents disease in adult dairy cows. This study demonstrated that pasteurization of colostrum before feeding to calves is beneficial in reducing the level of infection. This information provides a useful management tool for dairy producers in allaying the spread of infectious disease to their calves and improving their health. Technical Abstract: Feeding colostrum from infected dams to neonatal calves is one mode of transmission of paratuberculosis (Johne’s disease). Recent studies have demonstrated improved morbidity and mortality rates in calves fed colostrum replacers or pasteurized colostrum. In the present study, the potential benefits of feeding pasteurized colostrum were demonstrated in calves born to dams naturally infected with Mycobacterium avium subsp. paratuberculosis. Calves were separated at birth from their dams and randomly allocated into a group fed either their dam’s colostrum (DC; n = 6), followed by feeding the dam’s milk for 3 weeks and then milk replacer; or into a group fed pooled pasteurized colostrum (PC; n = 5), followed by milk replacer. At 6 weeks of age, calves were weaned onto calf starter and housed and fed in a similar manner throughout the rest of the study. Blood and fecal samples were taken at birth and monthly throughout the 12-month study. Calves were necropsied at the end of the study and 25 tissue sites were sampled from each animal and cultured for M. avium subsp. paratuberculosis. Sixteen of the 25 tissue sites were positive for calves across both treatment groups, with 14 of the 16 tissue sites positive for DC calves and 9 of the 16 tissue sites positive for calves fed the pasteurized colostrum (PC). The degree of colonization within a tissue was low and was variable for calves within treatment groups. Fecal shedding was minimal during the study with 2 calves from each treatment group shedding negligible amounts of M. avium subsp. paratuberculosis during the 12-month study. As a measure of the early immune response to infection, blood obtained from calves was stimulated in vitro with M. avium subsp. paratuberculosis antigen preparations and IFN-gamma secretion was measured. Antigen-specific IFN-gamma was consistently higher throughout the study in calves fed nontreated colostrum and milk from their naturally infected dams (DC; Abs450nm = 0.95 ± 0.19) as compared to calves fed pooled pasteurized colostrum (PC; Abs450nm = 0.43 ± 0.10) from noninfected donors. These results indicate that feeding a source of clean colostrum to neonatal calves may reduce their exposure to M. avium subsp. paratuberculosis. |
