Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: March 5, 2012
Publication Date: June 28, 2012
Citation: Wiggans, G.R., Wright, J.R., Muenzenberger, C.J., Neitzel, R.R. 2012. Genetic evaluation of mobility for Brown Swiss dairy cattle. Journal of Dairy Science. 95(Suppl. 2):267(abstr. T43). 2012. Technical Abstract: Genetic parameters were estimated for mobility score and 16 current linear type traits for Brown Swiss dairy cattle. Mobility is defined as a composite trait measuring the cow’s ability to move as well as the structure of her feet, pasterns, and legs. Scores from 50-99 were assigned by appraisers for the Brown Swiss Cattle Breeders Association beginning in June 2007. Only scores made before 69 mo of age were used. After edits, 32,710 records were available for 19,472 cows in 819 herds. The model included fixed effects for the interaction of herd and appraisal date (2109 groups); appraisal age within parity (46 groups); lactation stage within parity (21 groups), as well as random effects for animal, permanent environment and residual error. A multitrait analysis was run using canonical transformation, multiple diagonalization, and a decelerated expectation-maximization REML algorithm. Resulting heritability was 0.21 for mobility, and ranged from 0.06 to 0.37 for the other 16 type traits. The traits with the highest genetic correlation with mobility were final score (0.78), rear legs rear view (0.74), rear udder width (0.52) and foot angle (0.51). Predicted transmitting ability (PTA) for mobility was calculated using the current Brown Swiss multitrait type evaluation system, but using only appraisals where all traits were scored. For 1868 bulls evaluated, PTA mobility ranged from 1.6 to –1.8, standard deviation 0.5, and was most highly correlated with the PTA for final score (0.88), rear legs rear view (0.77), rear udder height (0.70) and rear udder width (0.69), similar to the trait correlations as was expected. When matched with official evaluations from August 2011, PTA mobility had moderately high correlations with PTA of milk, fat, protein, and productive life (0.31 to 0.41). The mobility trait may increase accuracy and timeliness of predictions of productive life by increasing the accuracy of the foot and leg composite.