Genetic parameters for paratuberculosis infection and effect of infection on production traits inIsraeliHolsteins

Abstract

Paratuberculosis (Johne's disease) is an infectious enteric disease in dairy cattle and other species that causes substantial economic loss worldwide. In this study, two recursive Gaussian-threshold models were employed in order to infer the effects of Johne's disease on milk yield, fat yield, and protein yield while simultaneously estimating genetic parameters (i.e. heritability and genetic correlation) in an Israeli Holstein population. Disease diagnosis was based on ELISA serum antibody tests. Data were available for 4694 daughters of 361 sires; 3.5% were positive; and 1.6% were suspect for the disease test. Disease status was coded either as a binary character (negative vs. positive) or as an ordered categorical trait (negative, suspect, and positive) in the two recursive models and as a binary trait in a linear model. Among sires with ≥ 50 daughters, predicted probability of Mycobacterium avium ssp. paratuberculosis (MAP) infection in future daughters ranged from <1% to 16.5%. Heritability estimates for Johne's disease were near 0.15, confirming a genetic contribution to disease susceptibility. Genetic correlation estimates for Johne's disease with the three yield traits were 0.15-0.22. Residual correlations for Johne's disease with the yield traits were between -0.01 and -0.10. For the linear regression model, yield losses associated with a positive disease diagnosis during 305 days of lactation were 300 kg milk and around 10 kg for fat and protein. Yield loss estimates from the recursive models were 25-50% less than linear model estimates. Recursive modeling has theoretical advantages over linear models for these phenotypes, but the estimated genetic parameters in this study did not differ significantly between the two types of models.

Associations between &lt;i&gt;paratuberculosis&lt;/i&gt; status and milk production traits in Holstein cattle under consideration of interaction effects between test result and farm and lactation number

“…In general, the results about the decrease in milk kg in positive animals from the literature are heterogeneous and range between 206 kg and 1 364 kg per lactation (Shook et al 2012, Raizman et al 2009, Richardson & More 2009, Sorge et al 2011, Tiwari et al 2007. One reason for this wide range of differences between MAP positive and negative tested animals could be the difference in the tests used or in the definition of MAP status itself.…”

Genome-Wide Association Analysis and Genomic Prediction of Mycobacterium avium Subspecies paratuberculosis Infection in US Jersey Cattle

“…Residual variance was set to 1. Assuming an average heritability of 0.1 for susceptibility to MAP -infection in dairy cattle [10], [11], [12], [13], [14], [15], 0.11 was used as a prior for genetic variance (). was assumed to have a scaled inverse chi-squared distribution with 4 degrees of freedom and scale parameter .…”

“…under the influence of both genetic and environmental factors. Studies have shown that susceptibility to JD is heritable with the estimates ranging from 0.03 to 0.28 in cattle [10], [11], [12], [13], [14], [15], [16], [17].…”

Knowledge gaps that hamper prevention and control ofMycobacterium aviumsubspeciesparatuberculosisinfection

“…However, before these markers can be used to guide selection, undesirable genetic linkages need to be identified. Such a counterproductive linkage occurred when high milk production was genetically associated with slightly increased susceptibility to MAP (Shook, Chaffer, Wu, & Ezra, ). In addition, genetic linkage studies can be expanded from identifying direct associations with susceptibility to infection to associations (e.g., likelihood of progression to clinical disease, specific responses to vaccination or tendency to progress to supershedding) (Table ).…”

“…However, before these markers can be used to guide selection, undesirable genetic linkages need to be identified. Such a counterproductive linkage occurred when high milk production was genetically associated with slightly increased susceptibility to MAP (Shook, Chaffer, Wu, & Ezra, 2012).…”