Asociación entre las características morfológicas y la producción de leche en vacas holstein

Abstract

The aim of this study was to identify the type traits that may help to explain the variation in milk production in Holstein cows. Animals were from four commercial dairies from Buenos Aires, Argentina (n= 1,290) that were morphometrically scored. The 15 morphological traits used were: fore udder attachment (FU), rear udder height (RUH), rear udder width (RUW), udder cleft (UC), udder depth (UD), teat placement (TP), teat length (TL), stature (ST), angularity (ANG), strength (GS), rump width (RW), rump angle (RA), feet and legs, rear view (RLRV), feet and legs, side view (RLS), and foot angle (FA). The qualification system used was proposed by ACHA (Asociación de Criadores de Holando Argentino). We applied the classification tree algorithm on the two categories of milk production (high and low production) that was previously defined by the percentiles 33 and 66 of the variable 305 days mature equivalent (305ME). The classification regression tree algorithm represents an alternative multivariate approach to the classical regression models. However, results were not affected by correlations between the variables. The results suggest that high scores of the trait rear udder width and high scores of the trait strength were associated with greatest milk production.