Phenotypic Factor Analysis for Linear Type Traits in Beijing Holstein Cows

Factor analysis was applied to the phenotypic correlation matrix of 15 linear type traits (scored linearly 1 to 50 points) for 2035 Holstein cows of 38 sires computed from data collected between 1988 and 1992 in Beijing Shuangqiao Farm and Beijing Xijiao Farm. The 15 linear type traits were stature, body strength, body depth, dairy form, rump angle, rump length, rump width, rear leg side view, foot angle, fore udder attachment, rear udder height, rear udder width, udder cleft, udder depth and teat placement rear view. The first four components accounted for 49.1% of the total variance in type scores. Factor 1 reflected strong cows, with deep bodies, with long and wide rumps, and tall in stature. Factor 2 reflected cows with well attached fore udders, wide rear udders and whose udders were supported by strong suspensory ligaments with close teat placement. Factor 3 reflected cows with good dairyness, sickled in the hocks, high rear udders and udder floors above the hocks. Factor 4 reflected cows with sloping rumps from hooks to pins and with steep foot angle. Principal component and factor analyses are useful to clarify the relationships among type traits.