GENOMIC AND IMMUNOLOGICAL CHARACTERISTICS OF JOHNE'S DISEASE
Location: Infectious Bacterial Diseases Research Unit
Title: Evaluation of Control Points in Youngstock and Adult Dairy Cow Management to Control Transmission of Mycobacterium avium subsp. paratuberculosis
| Godden, S - UNIV. OF MN |
| Wells, S - UNIV. OF MN |
| Gardner, I - UC-DAVIS |
| Fetrow, J - UNIV. OF MN |
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 7, 2008
Publication Date: December 7, 2008
Citation: Godden, S., Wells, S., Gardner, I., Fetrow, J., Stabel, J.R. 2008. Evaluation of Control Points in Youngstock and Adult Dairy Cow Management to Control Transmission of Mycobacterium avium subsp. paratuberculosis [abstract]. Conference of Research Workers in Animal Diseases. p. 82.
Complete a series of controlled on-farm trials to critically evaluate the efficacy and cost-benefit of commonly recommended management practices for reducing the transmission of Mycobacterium avium subsp. paratuberculosis (Map) in infected herds.
Objective 1. Evaluate the effect of maternity pen management (individual vs. group pens) on Map transmission in newborn calves. In 2005 pregnant cows from three Minnesota herds with clinical Johne’s disease and seroprevalence for Map > 10% were systematically allocated to calve in either individual cow maternity pens or a multiple cow maternity housing area. 456 heifer calves were enrolled. In 2007, enrolled calves were tested at approx. 2 yrs of age for subclinical Map infection using a serum ELISA antibody test and bacterial culture for isolating Map from fecal samples. Funding has been obtained for another year of testing and study cows are to be sampled for testing in the second and third lactations in 2008 and 2009.
Objective 2. Evaluate the effect of off-site (vs. on-site) heifer rearing on Map transmission in youngstock. A prospective cohort study was implemented in a 3100-cow California dairy to test the hypothesis that off-site rearing of heifers results in a lower incidence of Map. Three cohorts of approximately 800 heifers each (cohort 1: totally raised on site; cohort 2: raised on site until about 5 months of age and then off-site in Nevada, cohort 3: raised totally offsite at a calf ranch that uses milk replacer with subsequent rearing in Nevada) were enrolled in the study. For animals in cohorts 1, 2 and 3, testing in the first lactation showed 5.9%, 4.4% or 2.2% were fecal culture positive and 3.8%, 3.4% and 2.3% were ELISA positive for Map, respectively. Testing is continuing in lactations 2 and 3 in 2008 and 2009.
Objective 3. Evaluate the effect of feeding maternal colostrum (vs. colostrum substitute) on the risk for Map transmission in newborn calves. In 2003 433 newborn heifer calves from 12 dairy herds in MN and WI were fed either a) raw maternal colostrum (MC) or b) a commercial colostrum replacer (CR) (Acquire®. A.P.C. Inc. Ames, IA). All animals were tested for Map at approx. 30, 42 and 54 mos of age using serum ELISA and fecal culture. The cumulative proportion of study animals testing positive for Map was 12% (31/261) in the MC vs. 8% (18/236) in CR group, respectively. Survival analysis indicated that a 44% (Haz. ratio = 0.56, P = 0.056) reduction in the hazard of Map infection for the CR-fed group as compared to the MC-fed group (Pithua et al., JAVMA. Accepted).
Objective 4. Evaluate the effect of feeding pasteurized waste milk (vs. commercial milk replacer) to control Map transmission in dairy calves. In 2002 438 heifer and bull calves were assigned at 1-2 d of age to be fed either a) pasteurized non-saleable milk (PM) or b) a commercial 20:20 milk replacer (MR) until weaned. Preweaning health, performance, and economics have been described (Godden et al., JAVMA. 2005. 226:1547). Due to the unforseen sale and dispersal of one large study herd, approx. 50% of heifers were lost to long-term follow-up. A first lactation calving event was reported for 119 adult animals (MR = 54; PM = 65). Of these, the proportion removed from the herd by the end of the study follow-up period was 53.7% and 41.5% for calves originally fed MR or PM, respectively. Survival analysis showed that cows fed MR were at higher risk for removal from the herd between first calving and the end of the study follow-up period (Hazard ratioMR = 1.38, P < 0.05). Also, cows fed MR produced an estimated 1,935 kg less milk in the first two lactations, as compared to cows originally fed PM (P = 0.084). Testing using blood and fecal samples collected from study animals at an average of 25.0, 42.4 and 56.5 mos. of age indicated there was no difference in risk for a positive Map test for cows fed MR (27.8%) as compared to cows fed PM (21.5%) (Hazard ratioMR = 1.378; P = 0.36).
Objective 5. Evaluate the effect of delaying exposure to Map until adulthood on the development of new infections in adult dairy cows. This study will compare rates of subclinical and clinical Map infection in cattle raised in an environment presumed free of Johne’s disease to those of cattle raised in an environment presumed to be infected. Preliminary results from testing in 2004 indicate that dairy cattle raised in Johne’s low risk herds (Level 3 or 4) and introduced to Johne’s infected herds were less likely to test positive for Johne’s disease than herdmates raised in infected herds (OR = 0.10, 95% CI = 0.01-0.75 for antibody to Map and OR = 0.38, 95% CI = 0.14-0.98 for bacterial culture for Map in feces). Follow-up testing is ongoing.
Impacts: Results from Objective 3 suggest that raw maternal colostrum is an important source of Map transmission and that feeding a colostrum replacer is an effective control point to help reduce the risk for Map transmission in newborns. Results from Objective 4 indicate that, if raw milk is indeed an important source of Map transmission to calves, then on-farm pasteurization was effective in destroying viable Map in the milk or else reduced concentrations to levels below an infective dose. Furthermore, the results add to the increasing body of evidence indicating the importance of neonatal nutrition on long term performance. Work on objectives 1, 2 and 5 is ongoing.