Analysis of the phenotypic relationships between type traits and functional survival in Czech Fleckvieh cows
L. Zavadilová, M. Štípková, E. Němcová, J. Bouška, J. Matějíčkováhttps://doi.org/10.17221/29/2009-CJASCitation:Zavadilová L., Štípková M., Němcová E., Bouška J., Matějíčková J. (2009): Analysis of the phenotypic relationships between type traits and functional survival in Czech Fleckvieh cows. Czech J. Anim. Sci., 54: 521-531.
The phenotypic relationships between type traits and functional traits were analyzed in 47 786 Czech Fleckvieh cows first calved from 1994 to 2003. Functional survival was defined as the number of days from first calving to culling. All the cows were scored for conformation during the first lactation. Type information consisted of phenotypic type scores for 17 objectively scored linear type traits (with 9 classes each) and of the measurements for 6 body traits (measured in cm). The impact of the chosen conformation traits on functional longevity was estimated using the Cox proportional hazards model. The statistical model included the combined time-dependent effects of lactation and stage of lactation, age of the first calving, effects of the herd of culling, effects of year-season of culling, effects of the first lactation milk yield calculated within herd-year deviation. Analysis was performed separately for each of 23 type traits. The relative culling risk was calculated for animals in each class after taking into account the previously mentioned effects. All the traits analysed showed a relationship with the functional survival. Among linear type traits, rump angle, body depth, rear legs side view and pastern, fore udder length, rear udder attachment, and teats traits exhibited an intermediate optimum. Height at the sacrum, muscularity, rump length, and rump width, hock, and hoof angle, central ligament, and udder depth tended toward a linear relationship to functional survival. Body measurement traits showed an almost linear relationship concerning longevity except for chest girth, which exhibited an intermediate optimum. Body measurement traits and body conformation traits had an impact on functional survival especially in extreme classes, e.g. extremely ascending rump. Larger, broader, muscular cows had a higher risk of being culled compared with smaller and narrower cows and, hence, a shorter length of productive live. Foot and leg traits had an important influence on functional longevity, especially rear legs side view and pastern. Among udder traits, fore udder length, rear udder attachment, and front teat placement showed a higher impact on cows’ longevity than the other analyzed udder traits.Keywords:cattle; longevity; type traits; phenotypic relationship; survival analysis