Familial associations with paratuberculosis ELISA results in Texas Longhorn cattle

Control of paratuberculosis in beef cattle

As with any susceptible livestock species, the key to control of paratuberculosis in beef cattle is to reduce exposure of the susceptible calves to Mycobacterium avium subsp. paratuberculosis (MAP)–contaminated feces. Because beef calves remain with mature, potentially shedding cattle until weaning, control strategies are aimed at providing an environment with the least possible fecal burden and removing MAP shedders as soon as possible. Testing and culling or separation may be more important in beef cattle than in dairy cattle. Seedstock owners have greater potential for economic loss from paratuberculosis, making control program more financially attractive to them than to commercial beef cattle producers.

Familial and herd-level associations with paratuberculosis enzyme-linked immunosorbent assay status in beef cattle

A cross-sectional study was performed to determine the odds of having a positive paratuberculosis ELISA result if the dam was ELISA positive in Texas beef cattle, adjusted for individual and herd-level risk factors for seropositivity. Texas beef cattle (n = 2,621) were tested for paratuberculosis by using a commercial ELISA and microbiologic culture of feces for Mycobacterium avium subsp. paratuberculosis (MAP). Pedigree data were collected to identify dam-and sire-offspring pairs. Bayesian mixed-effects logistic regression was used to estimate the odds of seropositivity associated with age, dam ELISA status, sire ELISA status, herd size, herd history of clinical paratuberculosis, within-herd seroprevalence, within-herd fecal MAP prevalence, and within-herd fecal non-MAP Mycobacterium spp. prevalence. Herd of residence was included as a random effect to account for the correlation of observations within the same herd. Statistically probable associations were observed between ELISA status and herd fecal MAP prevalence [OR (odds ratio) 1.28 per 1% increase; P < 0.001] and herd seroprevalence (OR 1.21 per 1% increase; P < 0.001). The association with dam ELISA status was small (OR 1.35) and not highly probable (P = 0.69). Results indicate that use of dam ELISA status to make culling decisions in beef cattle may not improve the success of paratuberculosis control programs. Alternative strategies may be more effective for reducing the odds of seropositivity.