Best Linear Unbiased Prediction(BLUP) for Sires Depending on Days Open of Their Daughters in a Herd of Holstein

F. Al-Samarai

Abstract


A total of 13801 records belonging to 4100 Holstein cows raised at Al-Nasr Dairy Cattle Station were analysed from 1992 to 2003.
The aim of this study is to investigate the effect of some fixed factors (season and year of calving, parity, sex of calf and age at first calving) on days open and to estimate heritability in addition to estimate Best Linear Unbiased Prediction(BLUP) for sires depending on the days open of their daughters.
General Linear Model(GLM) of SAS program 2001 was used to calculate the effects of some fixed factors. Variance components were estimated by the Minimum Variance Quadratic Unbiased Estimation(MIVQUE) procedure.
Harvey program was also used to obtain BLUP values of 97 Holstein sires.
The overall mean of days open was 173.06 day and the effects of all fixed factors were significant (P < 0.01) except for age at first calving.
Heritability estimates of first, second, third, fourth, fifth, sixth and total days open were 0.00, 0.03, 0.002, 0.005, 0.07, 0.005 and 0.02, respectively.
The corresponding phenotypic trends for the same traits were – 0.60, – 4.65, –7.91, –9.86, –12.23, –12.37 and – 4.46 day/ year, and all of them were significant (P < 0.01) except the phenotypic trend of the first days open.
Best linear unbiased estimation for 97 sires ranged from –12.99 to 14.80 days.

Keywords


Genetic evaluation, Phenotypic trend, Days open, Dairy cattle

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