Genetic analysis of functional longevity in Holstein cattle

Abstract

Records of 1039 Holstein cattle were analyzed. Cows were culled during years from 1998 to 2004 at the Nasr Dairy Cattle Station, United Company for Animal Resources Ltd., Al-Soueira. General linear model within the SAS program was used to study the effect of some fixed factors (season and year of birth , stage of lactation and level of first milk yield ) on longevity. Results obtained that season of birth have a significant effect ( P < 0.05 ) on longevity, whereas the residual factors had a high significant effect ( P < 0.01 ). The heritability of founctional and true longevity using MIVIQUE method were 0.03 , 0.008 respectively and the corresponding heritability were 0.04 and 0.03 by using TYPE 1 method. Best linear unbiased pridiction ( BLUP ) for 24 sire using Harvey program were ranged from 17.15 to – 11.71 months respectively