Models for genetic evaluations of claw health traits in Spanish dairy XXXX .

@entity11536 @entity146 @entity1373 @entity2688 @entity74 @entity62 @entity291
UNASSIGNED: Genetic parameters of 7 claw health traits from Spanish dairy @entity291 were estimated and the predictive ability of linear and ordinal threshold models were compared and assessed. This study included data on @entity11536 (DE), sole ulcer (SU), @entity62 ( @entity62 ), @entity1373 ( @entity1373 ), @entity2688 (CL) collected between July 2012 and June 2013 from 834 dairy herds visited by 21 trained trimmers. An @entity74 ( @entity74 ) was also considered an indicator the absence or the presence of at least 1 of the 6 disorders. Claw health traits were scored as categorical traits with 3 degrees of severity (nonaffected, mild, and @entity146 ). Genetic parameters were estimated by fitting both a standard linear model and an ordinal threshold animal model. Around 21% of @entity291 had at least 1 @entity74 , and the most frequent disorders were SU, DE, @entity62 , and CL. Heritabilities of @entity74 estimated with a linear model ranged from 0.01 ( @entity2688 ) to 0.05 ( @entity74 ), whereas estimates from the ordinal threshold models ranged from 0.06 to 0.39 (for @entity2688 and @entity1373 , respectively). Repeatabilities of claw health estimated with the linear model varied from 0.03 to 0.18 and estimates with the ordinal threshold model ranged from 0.33 to 0.69. The global trait @entity74 was correlated with all disorders, except for @entity1373 and @entity2688 when the linear model was fitted. Two different genetic backgrounds of @entity74 were found. @entity11536 showed positive correlations with @entity1373 and @entity2688 , whereas SU was positively correlated with @entity62 and CL. The predictive ability of the models was assessed using mean squared error and Pearson correlation between the real observation and the corresponding prediction using cross-validation. Regardless of the claw health status, the linear model led to smaller mean squared error. However, differences in predictive ability were found when predicting nonaffected and affected animals. For most traits, healthy @entity291 were better predicted using the threshold model, whereas the linear model fitted affected @entity291 better. Correlations between the observed data and corresponding predictions support those results ranging from 0.01 to 0.34. Claw health traits showed enough genetic variance to be included in the selection goal for Spanish Holsteins to select animals with less susceptibility to claw health problems, and we suggest the linear model for implementing genetic evaluations of claw heath traits.
