|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/1998
Publication Date: N/A
Technical Abstract: Heritabilities for female survival to seven specific ages were estimated with a linear model and a generalized linear mixed model. Data for animals born in years 1970-1976 were collected from Cycles I-III of the Germ Plasm Evaluation Project at the U.S. Meat Animal Research Center. The females were two-breed crosses representing 16 breeds of sire. Records on a total of 2674 females from 372 sires were used. Survival was scored as 1 if the female survived from birth to a specific age and otherwise a 0. Each spec- ified age (1 to 7 yr) was considered a different trait. For analyses assuming a linear model, variance components were estimated using MTDFREML (Boldman and Van Vleck 1991), for analyses with a generalized linear mixed model GLIMMIX (SAS, 1994) with a probit link and binomial distribution was used. In both cases a sire model with no relationships among the sires was assumed. Models included fixed effects of sire breed, dam breed, year of birth, sire-dam breed interaction and day of birth as a linear covariate. Estimates of heritability were obtained from single-trait analysis for each survival age for each of the three cycles. Heritability estimates for survival to 1 to 7 yr for females of Cycle I were 0.106 vs 0.321, 0.075 vs 0.087, 0.074 vs 0.146, 0.016 vs 0.031, 0.020 vs 0.034, 0.034, vs 0.056, and 0.030 vs 0.052, for the linear and generalized linear mixed models, respectively. For females of Cycle III were 0.031 vs 0.0, 0.080 vs 0.0, 0.115 vs 0.0, 0.085 vs 0.025, 0.140 vs 0.088, 0.170 vs 0.183, and 0.375 vs 0.705, for the linear and generalized linear mixed models, res- pectively. Heritability estimates were greater for survival from birth to one year of age with both methods.