The effects of progressing and nonprogressing Mycobacterium avium ssp. paratuberculosis infection on milk production in dairy cows

Abstract

Longitudinal data from 3 commercial dairy herds in the northeast United States, collected from 2004 to 2011, were analyzed to determine the effect of Mycobacterium avium subsp. paratuberculosis (MAP) infection status and progression path on milk production. Disease status, as indicated by MAP test results, was determined through quarterly ELISA serum testing, biannual fecal culture, and culture of tissues and feces at slaughter. Milk production data were collected from the Dairy Herd Information Association. Animals with positive MAP test results were categorized, based on test results over the full course of the study, as high path (at least one high-positive culture) or low path (at least one positive culture or ELISA). The cumulative number of positive ELISA and culture results were recorded. The effects of both MAP infection path, status, and number of positive tests on milk production were analyzed using a mixed linear model with an autocorrelation random effect structure. Low and high path animals produced more milk prior to their first positive test than always-negative animals, especially high path animals. While mean production decreased after a first positive test, low path animals were shown to recover some productivity. High path animals continued to exhibit a decrease in milk production, especially after their first high-positive fecal culture. These results show that not all animals that test positive for MAP will have long-term production losses. Milk production decreased significantly with each additional positive test. Ultimately, production loss appeared to be a function of MAP infection progression.

Effects of subclinical Mycobacterium avium ssp. paratuberculosis infection on some physiological parameters, health status and production in dairy cows

“…Production loss is more severe in animals positive by faecal PCR than in those positive by ELISA (Gonda et al, 2007). According to Smith et al (2016), low-pathology animals (having only at least one positive culture or positive ELISA result) were shown to recover some productivity, while high-pathology animals (at least one highpositive culture) continued to exhibit a production decrease.…”

Mycobacterium avium paratuberculosis and Mycobacterium avium complex and related subspecies as causative agents of zoonotic and occupational diseases

“…The prevalence rate of bacilli prevalence at herd and livestock levels in European countries is 2–50% or higher. In Switzerland, this is 1.7–2.7%, Denmark 47%, Austria 19%, Belgium 18%, Ireland 9.5%, Italy 14.14% 8.2%, and in France is estimated to be 6.2–6.6% (Dore et al, ; Smith et al, ). In contrast, its rate in the United States has been estimated at the herd level of 21–93% and at least 2.9% for each dairy cattle (McKenna, Keefe, Tiwari, VanLeeuwen, & Barkema, ).…”

Economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study

“…The values for Q milk,i were taken from the results of the linear mixed model in Smith et al (Smith et al, 2016), with all covariate values set to the mean (for continuous covariates) or the mode (for discrete covariates) of the data used to fit the model.…”

“…The impact of paratuberculosis on milk production in dairy cattle differs significantly between these two groups of animals, with progressors demonstrating a continuous decrease in milk production (Smith et al, 2016). Non-progressors, by contrast, will experience a brief and limited decrease in milk production (Smith et al, 2016), from which their production levels will recover over time. This implies that the economic efficacy of test-and-cull programs will depend on their ability to distinguish between progressors and non-progressors.…”