Submitted to: Journal of the American Veterinary Medical Association
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/29/2009
Publication Date: 1/1/2011
Citation: Pithua, P., Wells, S.J., Godden, S.M., Stabel, J.R. 2011. Evaluation of the association between fecal excretion of Mycobacterium avium subsp paratuberculosis and detection in colostrum and on teat skin surfaces of dairy cows. Journal of the American Veterinary Medical Association. 238(1):94-100. 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 Mycobacterium avium subsp. paratuberculosis (MAP), in either the feces or milk of infected dams, bedding or cohabitation with other infected animals. This pathogen may spread to calves through colostrum from 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 or feeding “clean” colostrum from uninfected cows is an economical alternative to commercial colostrums products. This study evaluated the presence of MAP in colostrum and on teat surfaces of infected cows by PCR. This study demonstrated an overall significant positive association between detection of MAP in feces and detection of MAP DNA in colostrum. This information suggests that colostrum management may be a critical factor in the spread of paratuberculosis to young animals.
Technical Abstract: Objective—To evaluate the association between fecal excretion of Mycobacterium avium subsp paratuberculosis (MAP) by dairy cows in the periparturient period and detection of MAP DNA in colostrum specimens and on teat skin surfaces. Design—Cross-sectional study. Animals—112 Holstein cows. Procedures—Fecal specimens were collected within 48 to 72 hours prior to parturition, and colostrum and teat swab specimens were collected immediately after parturition. Detection of MAP in fecal specimens was performed via microbial culture, and detection of MAP DNA in colostrum and teat swab specimens was achieved via a PCR assay targeting the genetic element ISMAP02. Logistic regression was used to model the relationship between MAP fecal shedding status and detection of MAP DNA in colostrum or teat swab specimens. Population attributable fractions for the proportion of colostrum and teat swab specimens containing MAP DNA were also calculated. Results—The odds of detecting MAP DNA in colostrum or teat swab specimens in cows with MAP-positive (vs negative) fecal specimens were 2.02 and 1.87 respectively. Population attributable fractions estimates suggested that withholding colostrum from MAP-positive cows could reduce the odds of exposing calves to MAP in colostrum by 18.2%. Not permitting natural suckling by calves could reduce the odds of exposing calves to MAP on the teat surfaces of MAP-positive cows by 19.5%. Conclusions and Clinical Relevance—Results underscored the need for strict adherence to practices that limit contact of calves with adult cows from the time of birth and promote hygienic colostrum handling to avoid possible contamination with MAP during colostrum harvest, storage, or feeding.