Location: Infectious Bacterial Diseases ResearchTitle: Effect of feeding heat-treated colostrum on cell-mediated immune response to Mycobacterium avium subsp. paratuberculosis in neonatal dairy calves Author
|Shoyama, F - University Of Minnesota|
|Taya, J - Universidad De Sao Paulo|
|Wells, S - University Of Minnesota|
|Cheeran, M - University Of Minnesota|
|Sreevatsan, S - University Of Minnesota|
|Godden, S - University Of Minnesota|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2018
Publication Date: 6/4/2018
Citation: Shoyama, F.M., Taya, J.L., Wells, S.J., Stabel, J.R., Cheeran, M.C., Sreevatsan, S., Godden, S.M. 2018. Effect of feeding heat-treated colostrum on cell-mediated immune response to Mycobacterium avium subsp. paratuberculosis in neonatal dairy calves. Meeting Abstract. 113/58.
Technical Abstract: Background: Dairy calves can acquire Mycobacterium avium subsp. paratuberculosis (MAP) infection through the consumption of contaminated milk and colostrum. Heat treating (HT) colostrum (60 °C for 60 min) may be one management strategy to reduce risk of MAP infection via colostrum. We hypothesized that dairy calves fed HT colostrum at birth would have a reduced likelihood of a positive CMI test, suggesting a lower exposure/infection rate to MAP, as compared to calves fed fresh (FR) colostrum. Methods: A convenience sample of five Midwest Holstein dairy herds with confirmed Johne’s disease were selected. 250 newborn calves were enrolled and randomized to be fed either FR or HT colostrum within 2 h of birth. Heparinized venous blood samples were collected from calves at 4weeks and 4mos of age. Cells were stimulated with whole-cell sonicated MAP antigen, Concanavalin A (positive control) and PBS (negative control). Bovigam® ELISA assay was used to measure IFN-' levels in antigen-stimulated plasma. The results were expressed as optical density of T-cell responses of the sample and categorized as positive or negative for MAP exposure after normalization with PBS. FR and HT colostrum samples were tested for MAP on culture and by direct PCR for the IS900. Logistic regression models, accounting for random effect of calf within herd, were used to investigate the association between CMI test results (Pos/Neg) at 4wks and 4mos of age and the following risk factors: a) fed HT or FR colostrum, b) fed MAP-neg or MAP-pos colostrum. Results: CMI results were available for 223 calves (HT=111, FR = 112). The proportion of calves fed MAP-pos colostrum was significantly lower for calves fed HT (7.2%) versus FR (37.5%) colostrum (P=0.008). The odds of a negative CMI test did not differ between calves fed HT or FR colostrum at 4wks (HT = 87.4%; FR = 92.0%; OR = 0.58, 95% CI: 0.16, 2.08, P value=0.3) or at 4mos (HT = 91.9%; FR = 94.6%; OR: 0.68, 95% CI: 0.13,3.58, P value=0.55). The odds of a neg CMI test did not differ among calves fed MAP-Pos vs MAP-Neg colostrum at 4wks (MAP Pos = 94.0%; MAP Neg = 88.4%; P value=0.35) or at 4mos (MAP Pos = 96.0%; MAP Neg = 92.5%; P value=0.73). Conclusions: While feeding HT colostrum decreased the risk of feeding MAP-Pos colostrum to calves, treatment had no effect on CMI-positivity in dairy calves at 4wks and 4mos of age. Similarly, feeding MAP-Pos (vs MAP-Neg) colostrum had no association with CMI-positivity at both ages. These results raise the question of whether or not the CMI test is an appropriate test to indicate MAP exposure/infection in calves of this age due to the immaturity of the calf on immunological responses. Furthermore, the low number of IFN-' positive calves (4wks = 24; 4mos = 15) suggests that calf exposure was low, regardless of colostrum treatment.