| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Dairy Science, University of Wisconsin, Madison 53706
Corresponding author: K. A. Weigel; e-mail: weigel{at}calshp.cals.wisc.edu.
Survival analysis with a Weibull proportional hazards model was used to evaluate the effects of 15 linear type traits, 5 composite traits, and final score on the functional longevity of US Holstein cows. Culling data and type classification scores (measured in first lactation) from 891,524 cows with first calving from 1993 to 2000 were used. The data were divided into 9 geographical regions to determine whether the relationship between type traits and longevity differed according to climate or management system. Functional survival was defined as the number of days from first calving until culling or censoring, after correction for 305-d mature equivalent combined fat and protein yield. The Weibull model included time-dependent effects of herd-year-season, parity-stage of lactation, and within herd-year quintile ranking for combined fat and protein yield (nested within biennium), as well as time-independent effects of age at first calving and type classification score (type traits were analyzed one at a time). Type classification scores were rounded to the nearest 5 points, and the impact of each type trait on functional survival in each region was evaluated. Mean failure time ranged from 694 d in the South to 758 d in the North East. Risk of culling differed by region for several linear type traits, and differences were greatest for regions that were most dissimilar in climate and herd management (e.g., South East, East North Central, and West). Udder depth, fore udder attachment, udder cleft, and rear legs side view were consistently associated with functional longevity, regardless of region, but, the importance of some secondary traits, such as stature or dairy form, differed by region. The survival model applied in this study easily described both linear and nonlinear relationships between type traits and longevity while accounting for important time-dependent and time-independent explanatory variables.
Key Words: survival • Holstein • type trait • proportional hazard
This article has been cited by other articles:
|
|
 |
|
  E. Wall, M. P. Coffey, and S. Brotherstone The Relationship Between Body Energy Traits and Production and Fitness Traits in First-Lactation Dairy Cows J Dairy Sci, March 1, 2007; 90(3): 1527 - 1537. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. R. Wiggans, L. L. M. Thornton, R. R. Neitzel, and N. Gengler Genetic Parameters and Evaluation of Rear Legs (Rear View) for Brown Swiss and Guernseys J Dairy Sci, December 1, 2006; 89(12): 4895 - 4900. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Hare, H. D. Norman, and J. R. Wright Survival rates and productive herd life of dairy cattle in the United States. J Dairy Sci, September 1, 2006; 89(9): 3713 - 3720. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Wall, M. P. Coffey, and S. Brotherstone Body Trait Profiles in Holstein-Friesians Modeled Using Random Regression J Dairy Sci, October 1, 2005; 88(10): 3663 - 3671. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Wall, I. M. S. White, M. P. Coffey, and S. Brotherstone The Relationship Between Fertility, Rump Angle, and Selected Type Information in Holstein-Friesian Cows J Dairy Sci, April 1, 2005; 88(4): 1521 - 1528. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Sewalem, G. J. Kistemaker, and B. J. Van Doormaal Relationship Between Type Traits and Longevity in Canadian Jerseys and Ayrshires Using a Weibull Proportional Hazards Model J Dairy Sci, April 1, 2005; 88(4): 1552 - 1560. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Sewalem, G. J. Kistemaker, F. Miglior, and B. J. Van Doormaal Analysis of the Relationship Between Type Traits and Functional Survival in Canadian Holsteins Using a Weibull Proportional Hazards Model J Dairy Sci, November 1, 2004; 87(11): 3938 - 3946. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
