• Associations between paratuberculosis ELISA results and test-day records of cows enrolled in the Irish Johne's Disease Control Program

      Botaro, Bruno G.; Ruelle, Elodie; More, Simon J; Strain, Sam; Graham, David A.; O'Flaherty, Joe; Shalloo, Laurence; Department of Agriculture, Food and the Marine (Elsevier, 2017-07-12)
      The effect of the Mycobacterium avium ssp. paratuberculosis (MAP) ELISA status on test-day milk performance of cows from Irish herds enrolled in the pilot national voluntary Johne's disease control program during 2013 to 2015 was estimated. A data set comprising 92,854 cows and 592,623 complete test-day records distributed across 1,700 herds was used in this study. The resulting ELISA outcome (negative, inconclusive, and positive) of each cow within each year of the program was used to allocate the cow into different scenarios representing the MAP status. At MAPscenario1, all cows testing ELISA nonnegative (i.e., inconclusive and positive) were assigned a MAP-positive status; at MAPscenario2 only cows testing ELISA-positive were assigned a MAP-positive status; at MAPscenario3 only cows testing ELISA nonnegative (inconclusive or positive) and gathered exclusively from herds where at least 2 further ELISA nonnegative (inconclusive or positive) cows were found were assigned a MAP-positive status; at MAPscenario4 only cows testing ELISA-positive that were gathered exclusively from herds where at least 2 further ELISA-positive cows were found were assigned a MAP-positive status. Milk outputs based on test-day records were standardized for fat and protein contents (SMY) and the effect of MAP ELISA status on the SMY was estimated by a linear mixed effects model structure. The SMY mean difference recorded at test day between cows with a MAP-positive status and those with a MAP-negative status within MAPscenario1 was estimated at −0.182 kg/test day; the mean difference was −0.297 kg/test day for MAPscenario2; for MAPscenario3 mean difference between MAP-positive status and MAP test-negative cows was −0.209 kg/test day, and for MAPscenario4, the difference was −0.326 kg/test day.
    • Associations between paratuberculosis ELISA results and test-day records of cows enrolled in the Irish Johne's Disease Control Program

      Botaro, Bruno G.; Ruelle, Elodie; More, Simon J.; Strain, Sam; Graham, David A.; O'Flaherty, Joe; Shalloo, Laurence; Department of Agriculture, Food and the Marine (Elsevier for American Dairy Science Association, 2017-07-12)
      The effect of the Mycobacterium avium ssp. paratuberculosis (MAP) ELISA status on test-day milk performance of cows from Irish herds enrolled in the pilot national voluntary Johne’s disease control program during 2013 to 2015 was estimated. A data set comprising 92,854 cows and 592,623 complete test-day records distributed across 1,700 herds was used in this study. The resulting ELISA outcome (negative, inconclusive, and positive) of each cow within each year of the program was used to allocate the cow into different scenarios representing the MAP status. At MAPscenario1, all cows testing ELISA nonnegative (i.e., inconclusive and positive) were assigned a MAP-positive status; at MAPscenario2 only cows testing ELISA-positive were assigned a MAP-positive status; at MAPscenario3 only cows testing ELISA nonnegative (inconclusive or positive) and gathered exclusively from herds where at least 2 further ELISA nonnegative (inconclusive or positive) cows were found were assigned a MAP-positive status; at MAPscenario4 only cows testing ELISA-positive that were gathered exclusively from herds where at least 2 further ELISA-positive cows were found were assigned a MAP-positive status. Milk outputs based on test-day records were standardized for fat and protein contents (SMY) and the effect of MAP ELISA status on the SMY was estimated by a linear mixed effects model structure. The SMY mean difference recorded at test day between cows with a MAP-positive status and those with a MAP-negative status within MAPscenario1 was estimated at −0.182 kg/test day; the mean difference was −0.297 kg/test day for MAPscenario2; for MAPscenario3 mean difference between MAP-positive status and MAP test-negative cows was −0.209 kg/test day, and for MAPscenario4, the difference was −0.326 kg/ test day
    • Associations between paratuberculosis ELISA results and test-day records of cows enrolled in the Irish Johne's Disease Control Program

      Botaro, Bruno G.; Ruelle, Elodie; More, Simon J; Strain, Sam; Graham, David A.; O'Flaherty, Joe; Shalloo, Laurence; Department of Agriculture, Food and the Marine (Elsevier, 2017-07-12)
      The effect of the Mycobacterium avium ssp. paratuberculosis (MAP) ELISA status on test-day milk performance of cows from Irish herds enrolled in the pilot national voluntary Johne's disease control program during 2013 to 2015 was estimated. A data set comprising 92,854 cows and 592,623 complete test-day records distributed across 1,700 herds was used in this study. The resulting ELISA outcome (negative, inconclusive, and positive) of each cow within each year of the program was used to allocate the cow into different scenarios representing the MAP status. At MAPscenario1, all cows testing ELISA nonnegative (i.e., inconclusive and positive) were assigned a MAP-positive status; at MAPscenario2 only cows testing ELISA-positive were assigned a MAP-positive status; at MAPscenario3 only cows testing ELISA nonnegative (inconclusive or positive) and gathered exclusively from herds where at least 2 further ELISA nonnegative (inconclusive or positive) cows were found were assigned a MAP-positive status; at MAPscenario4 only cows testing ELISA-positive that were gathered exclusively from herds where at least 2 further ELISA-positive cows were found were assigned a MAP-positive status. Milk outputs based on test-day records were standardized for fat and protein contents (SMY) and the effect of MAP ELISA status on the SMY was estimated by a linear mixed effects model structure. The SMY mean difference recorded at test day between cows with a MAP-positive status and those with a MAP-negative status within MAPscenario1 was estimated at −0.182 kg/test day; the mean difference was −0.297 kg/test day for MAPscenario2; for MAPscenario3 mean difference between MAP-positive status and MAP test-negative cows was −0.209 kg/test day, and for MAPscenario4, the difference was −0.326 kg/test day.
    • The effect of paratuberculosis on milk yield—A systematic review and meta-analysis

      McAloon, Conor G.; Whyte, Paul; More, Simon J.; Green, Martin J.; O’Grady, Luke; Garcia, AnaBelen; Doherty, Michael L.; Department of Agriculture, Food and the Marine (American Dairy Science Association, 2015-12-10)
      Bovine paratuberculosis is a disease characterized by chronic granulomatous enteritis causing protein-losing enteropathy. Adverse effects on animal productivity are key drivers in the attempt to control paratuberculosis at the farm level. Economic models require an accurate estimation of the production effects associated with paratuberculosis. The aim of this study was to conduct a systematic review and meta-analysis to investigate the effect of paratuberculosis on milk production. A total of 20 effect estimates from 15 studies were included in the final meta-analysis. Substantial between-study heterogeneity was observed. Subgroup analysis by case definition and study design was carried out to investigate heterogeneity. The majority of between-study variation was attributed to studies that defined cases on serology. Calculation of a pooled effect estimate was only appropriate for studies that defined cases by organism detection. A reduction in milk yield, corrected for lactation number and herd of origin of 1.87 kg/d, equivalent to 5.9% of yield, was associated with fecal culture or PCR positivity in individual cows.
    • The effect of paratuberculosis on milk yield—A systematic review and meta-analysis

      McAloon, Conor G.; Whyte, Paul; More, Simon J.; Green, Martin J.; O'Grady, Luke; Garcia, AnaBelen; Doherty, Michael L.; Department of Agriculture, Food and the Marine (Elsevier, 2015-12-10)
      Bovine paratuberculosis is a disease characterized by chronic granulomatous enteritis causing protein-losing enteropathy. Adverse effects on animal productivity are key drivers in the attempt to control paratuberculosis at the farm level. Economic models require an accurate estimation of the production effects associated with paratuberculosis. The aim of this study was to conduct a systematic review and meta-analysis to investigate the effect of paratuberculosis on milk production. A total of 20 effect estimates from 15 studies were included in the final meta-analysis. Substantial between-study heterogeneity was observed. Subgroup analysis by case definition and study design was carried out to investigate heterogeneity. The majority of between-study variation was attributed to studies that defined cases on serology. Calculation of a pooled effect estimate was only appropriate for studies that defined cases by organism detection. A reduction in milk yield, corrected for lactation number and herd of origin of 1.87 kg/d, equivalent to 5.9% of yield, was associated with fecal culture or PCR positivity in individual cows.
    • The effect of paratuberculosis on milk yield—A systematic review and meta-analysis

      McAloon, Conor G.; Whyte, Paul; More, Simon J.; Green, Martin J.; O’Grady, Luke; Garcia, AnaBelen; Doherty, Michael L.; Department of Agriculture, Food and the Marine (Elsevier, 2015-12-10)
      Bovine paratuberculosis is a disease characterized by chronic granulomatous enteritis causing protein-losing enteropathy. Adverse effects on animal productivity are key drivers in the attempt to control paratuberculosis at the farm level. Economic models require an accurate estimation of the production effects associated with paratuberculosis. The aim of this study was to conduct a systematic review and meta-analysis to investigate the effect of paratuberculosis on milk production. A total of 20 effect estimates from 15 studies were included in the final meta-analysis. Substantial between-study heterogeneity was observed. Subgroup analysis by case definition and study design was carried out to investigate heterogeneity. The majority of between-study variation was attributed to studies that defined cases on serology. Calculation of a pooled effect estimate was only appropriate for studies that defined cases by organism detection. A reduction in milk yield, corrected for lactation number and herd of origin of 1.87 kg/d, equivalent to 5.9% of yield, was associated with fecal culture or PCR positivity in individual cows.
    • The genetic architecture of milk ELISA scores as an indicator of Johne's disease (paratuberculosis) in dairy cattle

      Brito, Luiz F.; Mallikarjunappa, Sanjay; Sargolzaei, Mehdi; Koeck, Astrid; Chesnais, Jacques; Schenkel, Flavio S.; Meade, Kieran G; Miglior, Filippo; Karrow, Niel A.; The Semex Alliance; et al. (Elsevier, 2018-09-13)
      Johne's disease (or paratuberculosis), caused by Mycobacterium avium ssp. paratuberculosis (MAP) infection, is a globally prevalent disease with severe economic and welfare implications. With no effective treatment available, understanding the role of genetics influencing host infection status is essential to develop selection strategies to breed for increased resistance to MAP infection. The main objectives of this study were to estimate genetic parameters for the MAP-specific antibody response using milk ELISA scores in Canadian Holstein cattle as an indicator of resistance to Johne's disease, and to unravel genomic regions and candidate genes significantly associated with MAP infection. After data editing, 168,987 milk ELISA records from 2,306 herds, obtained from CanWest Dairy Herd Improvement, were used for further analyses. Variance and heritability estimates for MAP infection status were determined using univariate linear animal models under 3 scenarios: (a) SCEN1: the complete data set (all herds); (b) SCEN2: herds with at least one suspect or test-positive animal (ELISA optical density ≥0.07); and (c) SCEN3: herds with at least one test-positive animal (ELISA optical density ≥0.11). Heritability estimates were calculated as 0.066, 0.064, and 0.063 for SCEN1, SCEN2, and SCEN3, respectively. The correlations between estimated breeding values for resistance to MAP infection and other economically important traits, when significant, were favorable and of low magnitude. Genome-wide association analyses identified important genomic regions on Bos taurus autosome (BTA)1, BTA7, BTA9, BTA14, BTA15, BTA17, BTA19, and BTA25 showing significant association with MAP infection status. These regions included 2 single nucleotide polymorphisms located 2 kb upstream of positional candidate genes CD86 and WNT9B, which play key roles in host immune response and tissue homeostasis. This study revealed the genetic architecture of MAP infection in Canadian Holstein cattle as measured by milk ELISA scores by estimating genetic parameters along with the identification of genomic regions potentially influencing MAP infection status. These findings will be of significant value toward implementing genetic and genomic evaluations for resistance to MAP infection in Holstein cattle.
    • Short communication: Uncovering quantitative trait loci associated with resistance to Mycobacterium avium ssp. paratuberculosis infection in Holstein cattle using a high-density single nucleotide polymorphism panel

      Mallikarjunappa, Sanjay; Sargolzaei, Mehdi; Brito, Luiz F.; Meade, Kieran G; Karrow, N. A.; Pant, S. D.; The Semex Alliance; NSERC; the Graham Centre for Agricultural Innovation; Darcy John O'Sullivan Bequest; et al. (Elsevier, 2018-05-10)
      Mycobacterium avium ssp. paratuberculosis (MAP) is the etiological agent of Johne's disease in cattle. Johne's disease is a disease of significant economic, animal welfare, and public health concern around the globe. Therefore, understanding the genetic architecture of resistance to MAP infection has great relevance to advance genetic selection methods to breed more resistant animals. The objectives of this study were to perform a genome-wide association study of previously analyzed 50K genotypes now imputed to a high-density single nucleotide polymorphism panel (777K), aiming to validate previously reported associations and potentially identify additional single nucleotide polymorphisms associated with antibody response to MAP infection. A principal component regression-based genome-wide association study revealed 15 putative quantitative trait loci (QTL) associated with the MAP infection phenotype (serum or milk ELISA tests) on 9 different chromosomes (Bos taurus autosomes 5, 6, 7, 10, 14, 15, 16, 20, and 21). These results validated previous findings and identified new QTL on Bos taurus autosomes 15, 16, 20, and 21. The positional candidate genes NLRP3, IFi47, TRIM41, TNFRSF18, and TNFRSF4 lying within these QTL were identified. Further functional validation of these genes is now warranted to investigate their roles in regulating the immune response and, consequently, cattle resistance to MAP infection.