Genetic analysis of cow survival in the Israeli dairy cattle population.
The linear model method of VanRaden and Klaaskate for analyzing 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 parities, but genetic correlations were close to unity. Animal model heritability estimates of herd life were higher than were sire model estimates. The expected herd life of pregnant cows was 420 d greater than for open cows. Each kilogram of 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 herd life 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 predicted herd life of live cows were strongly biased if all records were weighted equally, and evaluations derived by weighting incomplete records to account for the effects of current herd life on variance components were nearly unbiased.
Settar
P
P
Institute of Animal Sciences, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel.
Weller
J I
JI
D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics*; D005260:Female; D007557:Israel; D008136:Longevity / Q000235:genetics*; D008297:Male; D010298:Parity; D010641:Phenotype; D011247:Pregnancy; D012044:Regression Analysis