Genetic parameters for both a liver damage phenotype caused by Fasciola hepatica and antibody response to Fasciola hepatica phenotype in dairy and beef cattle1

Abstract

is a helminth parasite of economic importance to the global cattle industry, with documented high international herd prevalence. The objective of the present study was to generate the first published genetic parameter estimates for liver damage caused by as well as antibody response to in cattle. Abattoir data on the presence of live , or -damaged livers, were available between the years 2012 and 2015, inclusive. A second data set was available on cows from 68 selected dairy herds with a blood ELISA test for antibody response to in autumn 2015. Animals were identified as exposed by using herd mate phenotype, and only exposed animals were retained for analysis. The abattoir data set consisted of 20,481 dairy cows and 75,041 young dairy and beef animals, whereas the study herd data set consisted of 6,912 dairy cows. (Co)variance components for phenotypes in both data sets were estimated using animal linear mixed models. Fixed effects included in the model for both data sets were contemporary group, heterosis coefficient, recombination loss coefficient, parity, age relative to parity/age group, and stage of lactation. An additional fixed effect of abattoir by date of slaughter was included in the model for the analysis of the abattoir data. Direct additive genetic effects and a residual effect were included as random effects for all analyses. After data edits, the prevalence of liver damage caused by in cows and young cattle was 47% and 20%, respectively. The prevalence of a positive antibody response to in cows from the study herd data was 36% after data edits. The heritability of as a binary trait for dairy cows in abattoir data and study herd data was 0.03 ± 0.01 and 0.09 ± 0.02, respectively; heritability in young cattle was 0.01 ± 0.005. The additive genetic SD of as a binary trait was 0.069 and 0.050 for cows and young cattle from the abattoir data, respectively, and 0.112 from the study herd cows. The genetic correlation between liver damage caused by in young cattle and cows from the abattoir data was 0.94 ± 0.312 and the genetic correlation between liver damage caused by in cows and positive antibody response to in cows in the study herd data was 0.37 ± 0.283.

Candidate genes associated with the heritable humoral response to Mycobacterium avium ssp. paratuberculosis in dairy cows have factors in common with gastrointestinal diseases in humans

“…Twomey et al (2016) undertook a similar EBV validation exercise based on cows divergent in parental average EBV for liver fluke. The area reported under the receiver operating curver reported by Twomey et al (2016) was 0.522, with cows in the top (i.e., worst) 10% being 1.28 (95% CI = 1.05-1.36) times more likely to have livers damaged by liver fluke compared with contemporaries in the bottom (i.e., best) 10%. This difference in odds translated to a 6% unit probability difference between the top and bottom 10% of cows in the study cohort.…”

“…Only data from dairy herds were considered further. A herd was classified as beef or dairy based on the average breed composition of the cows, as per Twomey et al (2016). Cow breed composition was determined from the recorded breed composition of ancestors.…”

Genetic line comparisons and genetic parameters for endoparasite infections and test-day milk production traits

“…For dairy and beef cattle in Ireland grassland systems, Mc-Clure et al (2014) used a binary trait definition and estimated a lower heritability of 0.15 for the presence of liver flukes (F. hepatica). Twomey et al (2016) reported a smaller heritability, in the range from 0.01 and 0.09, for the binary traits liver damage caused by F. hepatica and antibody response to F. hepatica in Irish dairy and beef cattle. Threshold models for categorical endoparasite traits with 2 or more classes were also applied by Passafaro et al (2015).…”

Genetic correlations between endo-parasite phenotypes and economically important traits in dairy and beef cattle1

“…Milk production (Charlier et al, 2005;Mezo et al, 2011), reproductive performance Haddad et al, 2005;Charlier et al, 2007), and meat yield (Barling et al, 2000;Charlier et al, 2009a) have all been documented as compromised in cattle herds infected with Fasciola hepatica, Ostertagia ostertagi, or Neospora caninum. The high prevalence of infection in cattle with both F. hepatica and O. ostertagi (Sekiya et al, 2013;Twomey et al, 2016) suggests that current control practices (e.g., anthelmintic treatment; Bloemhoff et al, 2014) are sub-optimal. On the other hand, effective N. caninum control strategies (i.e., herd biosecurity and the culling of infected animals; Dubey et al, 2007) can be costly.…”

“…Using animal-level data for F. hepatica-damaged livers on >95,000 Irish dairy and beef cattle, Twomey et al (2016) reported the presence of significant underlying genetic variability suggesting that breeding strategies could be used as a supplementary control for F. hepatica. A limited number of studies exist in cattle that documented genetic parameters for phenotypes based on the other two endo-parasites of interest, O. ostertagi (n = 2; Morris et al, 2003;Coppieters et al, 2009) and N. caninum (n = 1; Pan et al, 2004).…”