Authors
Ni Gengler
Publication date
1996
Journal
Bulletin-International Bull Evaluation Service
Publisher
SLU
Description
The linear model method of VanRaden and Klaaskate to analyze herd life was expanded. Information on conception and protein yield was included in the estimation of predicted herd life of Israeli Holsteins. Variance components were estimated by a multitrait animal model. Heritability was slightly higher for herd life than for number of lactations, but genetic correlations were close to unity. Animal model heritability estimates of herdlife were higher than previous sire model estimates. The expected herd life of pregnant cows was 420 d greater than open cows. Each kg increase in protein yield increased expected herd life by 9.5 d. Heritability of expected herd life increased from 0.11 for cows 6 mo after first calving to 0.14 for cows 3 yr from first calving. The genetic correlation of expected and actual herdlife increased from 0.87 for records cut after 6 mo to 0.99 for records cut 3 yr after first calving. Phenotypic correlations increased from 0.61 to 0.94. Sire genetic evaluations based on expected herd life of live cows were strongly biased if all records were weighted equally, while evaluations derived by weighting incomplete records to account for the effects of current herd life on variance components were nearly unbiased.
Total citations
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