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Abstract

Objective—To evaluate progress made by cattle herds in the control of paratuberculosis (Johne's disease) through participation in the Minnesota Johne's Disease Control Program (MNJDCP).

Design—Retrospective records analysis.

Sample Population—Data for dairy and beef herds participating in the MNJDCP.

Procedures—Data for the MNJDCP were collected for analyses. Outcome measures included changes in numbers of participating cattle producers, risk assessment scores, and within-herd seroprevalence of Johne's disease by year of program participation.

Results—Results revealed steady increases in program participation by cattle producers in Minnesota over time, with > 30% of dairy producers and 2% of beef producers in the state participating by the end of 2006. Despite risk of introduction of Johne's disease to cattle herds through continued introduction of cattle from other herds, dairy and beef herds in the Management Program of the MNJDCP reduced their on-farm risk assessment scores during the program. Dairy herds in the Management Program reduced their mean within-herd seroprevalence 1.1% during the first year, 2.6% during the first 2 years, and 4.0% during the first 3 years of program participation. Significant within-herd seroprevalence reduction was also detected for beef herds that participated in the Management Program for at least 3 years.

Conclusions and Clinical Relevance—This study revealed a reduction in the risk of withinherd transmission of Johne's disease and seroprevalence over time in dairy and beef herds in the Management Program of the MNJDCP. This is consistent with a positive effect of the program for the control of Johne's disease in cattle.

Full access
in Journal of the American Veterinary Medical Association

Summary

Strategies for the elimination of pseudorabies virus (prv) from swine herds include test and removal, offspring segregation, and depopulation/repopulation. The prevalence of prv in a herd is a major factor in selection of the most appropriate strategy. The purpose of the study reported here was to describe the prevalence of prv in adult swine in prv quarantined herds in Minnesota, and to determine herd factors associated with the seroprevalence. Questionnaires describing the health history of the herd, management practices, and design of the swine facilities were obtained from the owners of 142 quarantined herds. Blood was collected from 29 finishing pigs over the age of 4 months, up to 29 adult females, and all herd boars. Factors considered to be significant in a bivariate analysis were combined in a stepwise multiple logistic regression analysis. The prevalence of prv-seropositive adults in each herd was bimodally distributed among the 142 herds. In 42 (30%) of the herds, none of the females tested was seropositive, which represented the lower mode. At least 90% of the adults tested were seropositive in 30 (21%) of the herds and represented the higher mode. The odds of the breeding swine of a given herd having a prv seroprevalence of ≥ 20% as compared with having a seroprevalence of < 20% was 1.654 times higher per 50 adults in the herd, 13.550 times higher if the finishing pigs were seropositive, 2.378 times higher if sows were housed inside during gestation, and 1.481 times lower per number of years since the imposition of quarantine. These findings indicate that a large proportion of quarantined herds may have a low seroprevalence of prv, making them prime candidates for test and removal. Pseudorabies virus might also be eliminated from these low-prevalence herds by a method referred to as management/vaccination, which is described. These methods are inexpensive, compared with offspring segregation or depopulation/repopulation, and represent a substantial cost savings for the swine industry.

Free access
in Journal of the American Veterinary Medical Association

Summary

Data were collected from 104 Minnesota swine farms quarantined for pseudorabies virus (prv) infection. Each herd was serologically evaluated for the presence of antibodies to prv in finishing pigs. Herd management practices, swine housing design, and disease profiles were described for each farm. Multiple logistic regression analysis was used to determine which factors were associated with circulation of prv in the finishing pigs of farrow-to-finish farms. Sixty-seven (64%) of the herds had no serologic evidence of prv circulation in the finishing section, whereas 37 herds (36%) contained at least one prv seropositive finishing pig. The odds of a given finishing herd being seropositive for prv were 2.85 times higher if the finishing pigs were housed in confinement (P = 0.01), 2 times higher if Actinobacillus (Haemophilus) pleuropneumoniae was a clinical problem in the herd (P = 0.03), 1.36 times less for each year that passed since the herd quarantine was issued (P = 0.01), 1.74 times higher if clinical signs of prv were reported (P = 0.04), and 1.52 times higher if animal protein was included in at least one of the rations (P = 0.08).

Free access
in Journal of the American Veterinary Medical Association