| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
* Department of Animal Sciences, University of Illinois, Urbana 61801 and
and
USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933-0166
2 Correspondence: E-mail: southey{at}uiuc.edu.
Mortality records of 8,642 lambs from a composite population at the U.S. Meat Animal Research Center during the first year of life were studied using discrete survival analyses. Lamb mortality was studied across periods from birth to weaning, birth to 365 d of age, and weaning to 365 d of age. Animal–time data sets were created for each period using different time intervals: daily, weekly, fortnightly, and monthly. Each data set was analyzed using logistic and complementary log–log sire, animal, and maternal effects models. Explanatory variables included in the models were duration of time interval, sex, type of birth, contemporary group, age of dam, and type of upbringing (nursery or not). Similar estimates of explanatory variables were obtained within the same period across models and different time intervals. Heritability estimates from the complementary log–log models were greater than those from the comparable logistic models because of the difference in variance of the respective link functions. Heritability estimates from the complementary log–log sire model ranged from 0.13 to 0.21 for all periods. These estimates were greater than the complementary log–log animal model estimates that ranged from 0.04 to 0.12. Maternal effects were important early in life, with the maternal heritability slightly greater than the direct additive heritability. Negative correlations (-0.72 to -0.65) between direct additive and maternal effects was estimated. The similarity of results among survival analysis methods demonstrates that the discrete methodology is a viable alternative to estimate variance components in livestock survival data.
Key Words: Analysis • Heritability • Mortality • Sheep • Survival
This article has been cited by other articles:
|
|
 |
|
  J. Maxa, A. R. Sharifi, J. Pedersen, M. Gauly, H. Simianer, and E. Norberg Genetic parameters and factors influencing survival to twenty-four hours after birth in Danish meat sheep breeds J Anim Sci, June 1, 2009; 87(6): 1888 - 1895. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Casellas, G. Caja, X. Such, and J. Piedrafita Survival analysis from birth to slaughter of Ripollesa lambs under semi-intensive management J Anim Sci, February 1, 2007; 85(2): 512 - 517. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. L. L. Guerra, D. E. Franke, and D. C. Blouin Genetic parameters for calving rate and calf survival from linear, threshold, and logistic models in a multibreed beef cattle population J Anim Sci, December 1, 2006; 84(12): 3197 - 3203. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Koenig, A. R. Sharifi, H. Wentrot, D. Landmann, M. Eise, and H. Simianer Genetic Parameters of Claw and Foot Disorders Estimated with Logistic Models J Dairy Sci, September 1, 2005; 88(9): 3316 - 3325. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. R. Southey, S. L. Rodriguez-Zas, and K. A. Leymaster Competing risks analysis of lamb mortality in a terminal sire composite population J Anim Sci, October 1, 2004; 82(10): 2892 - 2899. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
