Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2010
Publication Date: 11/1/2011
Citation: Pithua, P., Godden, S.M., Wells, S.J., Stabel, J.R. 2011. Evaluation of the risk of paratuberculosis in adult cows fed Mycobacterium avium subsp paratuberculosis DNA-positive or -negative colostrum as calves. American Journal of Veterinary Research. 72(11):1456-1464. 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 compared the efficacy of feeding “clean” colostrum and colostrum containing MAP to neonatal calves on the incidence of disease in once they reached the age of maturity. This study demonstrated that feeding colostrum containing MAP organisms did not impact the level of MAP infection in older animals. This information suggests that colostrum may not be a critical factor in the spread of paratuberculosis to young animals.
Technical Abstract: Objective - Estimate the risk of MAP infection in Holstein calves associated with ingestion of MAP DNA positive (vs negative) colostrum at birth. Animals - 205 Holstein heifer calves born in 12 commercial dairy herds. Procedure - Every calf born was separated from its dam within 30 to 60 minutes of birth and fed raw colostrum. For each calf, samples of the colostrum fed were collected and tested for presence of MAP DNA using a nested PCR of the target gene ISMAP02. Calves were classified into exposed (n = 69) and unexposed (n, 136) groups if fed colostrum positive or negative for MAP DNA. Each calf was tested for MAP infection at 30, 42, and 54 months of age using a serum ELISA and bacterial fecal culture tests. Logistic regression modeling with herd random effect was used to evaluate the association between exposure to MAP DNA positive colostrum and the risk of MAP infection. Results - Risk of MAP infection was not different between group (exposed vs unexposed) when serum ELISA (HR = 2.63, P = 0.24), bacterial fecal culture (HR = 1.45, P = 0.45) and either one or both diagnostic test (parallel interpretation; HR = 1.29, P = 0.63). Conclusions and Clinical Relevance - Heifer calves fed MAP DNA positive colostrum were at no greater risk of MAP infection as compared to heifer calves fed MAP DNA negative colostrum. This result contradicts findings from other studies and is inconclusive. (Am J Vet Res 2010; XXX-XXX)