Relationships between conformation traits and functional longevity in Holstein cows were evaluated using survival analysis. Functional longevity was defined as the number of days between the first calving and culling; that is, length of productive life. The data set consisted of 116,369 Holstein cows that first calved from 2003 to 2008. All cows used in the analysis were scored for conformation between d 30 and d 210 of their first lactation. The data included 48% censored records. Analyses were done separately for 20 linear descriptive type traits, 6 composite traits, and height at sacrum measured in centimeters. Cox proportional hazard models were fitted to analyze data. The hazard function was described as the product of a baseline hazard function and the time-independent effects of age at first calving and sire (random), and the time-dependent effects of stage of lactation and lactation number, herd, year and season, herd size, and 305-d milk production. The strongest relationship between a composite trait and functional longevity was for dairy form, followed by udder and final score. Among the descriptive type traits, the strongest relationships with longevity were found for body condition score, angularity, traits related to udder attachment, and udder depth. Foot and leg traits showed substantially lower effect on functional longevity, and the effect of foot angle was minimal. Functional longevity declined with decreased body condition score of cows. Cows with deep udders had significantly lower functional survival compared with cows with shallow udders. In addition, weak central ligament was associated with significant reduction of cow longevity. For dairy form and angularity, cows classified as very good were the worst with respect to longevity, whereas cows classified as poor were the best. An intermediate optimum was evident for rear legs rear view and rear legs set (side view), whereas cows with sickled legs had lower longevity than cows with straighter legs.

Genetic correlations between longevity and conformation traits were estimated using data on Czech Holstein cows first calved in the years 1993–2008. Longevity traits considered were length of productive life and number of lactations initiated and their functional equivalents (i.e. the longevity traits corrected for milk production). Conformation traits were twenty one linear descriptive type traits, six composite traits and height at sacrum measured in cm. A possible nonlinear relationship between conformation and longevity traits was also investigated. The heritabilities ranged from 0.05 to 0.43 for conformation traits and from 0.03 to 0.05 for longevity traits. Low to moderate genetic relationships between conformation and longevity traits were found. The genetic correlations were higher for functional longevity than for direct longevity traits. Negative genetic correlations with all longevity traits were found for height at the sacrum, stature, dairy form, body conformation, and capacity. Final score showed weak genetic correlation with all analyzed longevity traits. Positive genetic correlations occurred between feet and legs and direct longevity and functional longevity (0.19, 0.14) and between udder and direct longevity (0.10). Body condition score and angularity showed strong genetic correlations with functional longevity (body condition score 0.30, angularity –0.31). Foot and leg traits showed weak genetic correlations with longevity traits except rear legs set (side view) (–0.24) and hock quality (0.19). The udder traits showed inconsistent and rather weak genetic correlations with longevity traits, with the exception of a stronger genetic correlation between rear udder width and functional longevity (–0.22) and between central ligament and number of lactations (–0.18, –0.19). The teat traits showed always negative genetic correlations with longevity traits. The strongest correlations were found for rear teat position (–0.28) and the weakest for teat length (–0.03). Some conformation traits showed markedly stronger genetic correlations with functional longevity than with direct longevity (rear udder width and rear udder height, dairy form, body condition score, angularity, rear legs set (side view), rear legs rear view). A quadratic relationship between conformation and longevity traits did exist. Even if the linear relationship generally prevailed, the quadratic relationship should be taken into account.  

A primary reason for collecting and utilizing information on type is to aid breeders in selecting profitable, functional cows in order that early culling for causes unrelated to yield (involuntary culling) can be avoided (Misztal et al., 1992). Selection on yield traits alone could decrease merit for traits with antagonistic genetic correlations with yield. Selection emphasis on type traits associated with increased herd life may be beneficial to decrease involuntary culling and increase profitability (Rogers and McDaniel, 1989). Conformation traits are recorded in many dairy cattle breeds (Foster et al., 1988;Harris et al., 1992;de Haas, et al., 2007). These traits have medium to high heritability (Meyer et al., 1987) and can often be recorded in a single assessment, which makes them reliable and relatively inexpensive traits that can be included in selection indices for overall merit (Schaeffer et al., 1985;Wiggans et al., 2004).The objective of this study was to estimate genetic parameters for currently recorded type traits and to utilize them in the genetic evaluation system and eventually in selection indices. These new estimates should provide improved accuracy of type evaluations, particularly for traits whose (co)variances have changed over time. MATERIAL AND METHODS Data collectionType classification records were extracted from the Czech-Moravian Breeder's Association official The objectives of this study were to estimate genetic parameters for 18 currently recorded linear conformation traits in Czech Holstein cattle. The data set consisted of 78 886 first-lactating Holstein cows. Traits, all scored on a 9-point scale, were fore udder attachment, rear udder height, udder depth, rear udder width, central ligament, teat length, front teat placement, rear teat position, stature, angularity, chest width, body depth, rump angle, rump width, rear legs rear view, rear leg set (side view), foot angle, and bone quality. Uni-and bivariate animal models were used. The models included fixed effects of herd-date of classification-classifier, classifier, and season of calving, quadratic regressions on age at calving and on days in milk and the random effect of animal. Heritability estimates obtained in univariate and in bivariate analyses were of similar magnitude. Heritabilities ranged from 0.17 to 0.32 for udder traits, 0.10 to 0.16 for foot and leg traits, and 0.18 to 0.45 for traits related to body size. Genetic correlations among the currently recorded linear traits ranged from -0.67 between foot angle and rear leg set (side view) to 0.75 between fore udder attachment and udder depth. Substantial genetic correlations were found for the following pairs of traits: rear udder height and rear udder width (0.70), chest width and body depth (0.69), front teat placement and rear teat position (0.68), angularity and bone quality (0.67). Corresponding phenotypic correlations for most pairs of traits were similar in direction but smaller in magnitude than the genetic correlations.

No abstract

ABSTRACT:The relationships between conformation and longevity traits were analysed in 58 493 Czech Fleckvieh cows first calved from 1994 to 2003. All cows were scored for conformation during the first lactation. Genetic correlations between longevity and conformation traits were estimated by bivariate runs using the VCE 4.0 program for variance component estimation. The values of heritability for conformation traits were in the range from 0.06 to 0.63 and for longevity traits from 0.04 to 0.05. Low or intermediate genetic relationships between recorded linear traits and longevity trait were found. The correlations were lower for functional longevity. Body measurements showed negative genetic correlations with real as well as functional longevity (-0.12 to -0.29). The dairy character negatively correlated with longevity traits (-0.18 to -0.26). The muscularity and udder showed a zero correlation with functional longevity, while the feet and legs were not correlated with real longevity. The highest positive genetic correlations between real longevity and objectively scored linear type traits were found for hock (0.24), rear udder attachment (0.28), fore udder length (0.16) and central ligament (0.11). On the contrary, the correlation between the udder depth and the milk-corrected longevity was positive (0.28) and higher than in the case of real longevity.