This thesis described the role of raw bovine colostrum feeding programs and
natural nursing practices in the transmission of Mycobacterium avium subsp.
paratuberculosis (MAP), and the efficacy of commercially available colostrum
replacement products in preventing MAP transmission, additional to their effect on
production and longevity performance outcomes. Incidences of fecal excretion of MAP
by calves following natural exposure were also evaluated.
Calves fed CR (vs MC) had a lower risk of MAP infection when the serum ELISA
(HR = 0.474, P = 0.081), bacterial fecal culture (HR = 0.572, P = 0.076) or both test
combinations (HR = 0.559, P = 0.056) were used to define MAP status of study cohorts,
suggesting that MC could be an important vehicle by which calves become exposed to
MAP within hours following birth, and that CR feeding programs may be an effective
management tool for use in dairy herds in a Johne’s disease control effort.
From birth-to-54 months of follow-up, risk of death (HR = 1.22, P = 0.17), culling
(HR =1.01, P = 0.95), and death and/or culling (HR = 1.1, P = 0.61) event outcomes did
not significantly differ between groups (CR vs MC). Similarly there were no significant
differences between groups (CR vs MC) with respect to the risk of death (HR = 1.22, P =
0.46), culling (HR =1.01, P = 0.98), and death and/or culling (HR = 1.05, P = 0.85) event
outcomes when only heifers that entered the lactating herd (period from first calving date
to 54 months of age) were considered. Feeding CR (vs MC) had no significant effect on
age at first calving (P = 0.34), number of breedings per conception in the first (P = 0.83)
and second (P = 0.32) lactations respectively, and calving-to-conception intervals in the
first (P = 0.7) and second (P = 0.21) lactations, respectively. Considering the milk yield
outcome, feeding CR (vs MC) significantly (P = 0.02) decreased first lactation milk by
429 kg, although there were no significant effects of feeding CR (vs MC) on second
lactation (P = 0.18) and lifetime milk yields (P = 0.5), respectively.
Risk of MAP infection was not significantly different between groups of calves that
ingested MAP DNA positive colostrum (vs MAP DNA negative colostrum) when the
serum ELISA (HR = 0.74, P = 0.65), bacterial fecal culture (HR = 0.92, P = 0.85) or both
test combinations (HR = 0.82, P = 0.65) were used to define MAP status of study (HR = 0.74, P = 0.65), bacterial fecal culture (HR = 0.92, P = 0.85) or both
test combinations (HR = 0.82, P = 0.65) were used to define MAP status of study cohorts, suggesting lack of an added risk of MAP infection associated with ingesting
MAP DNA positive raw colostrum by Holstein calves. This finding contradicted several
other reports which seem to provide evidence in support of colostrum as a possible early
vehicle by which calves get exposed to MAP in infected herds.
Cows that were fecal culture positive were significantly more likely to have
detectable MAP in their colostrum (OR =2.02 , P < 0.001) and teat skin (OR =1.87 , P =
0.008) compared with fecal culture negative cows with the population attributable
fraction estimates for exposure for each of the latter outcomes being 18% and 19.5%,
Finally, MAP was not recovered from fecal samples collected between 1-to-90 d of
age and tested using the sedimentation bacterial culture method suggesting that the calves
studied did not excrete detectable levels of MAP in feces following natural exposure.
University of Minnesota Ph.D. dissertation. June 2009. Major: Veterinary Medicine. Advisors: Scott J Wells and Sandra M Godden. 1 computer file (PDF); ix 145 pages.
Efficacy of interventions and role of raw colostrum feeding programs in the transmission of Mycobacterium avium subsp. paratuberculosis..
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