Genetics aspects of reproductive performance for Holstein

F.R, Al-Samarai; N.N, Al-Anbari; Y.K, Al-tmimi

	Genetics aspects of reproductive performance for Holstein
The Iraqi Journal of Veterinary Medicine (IJVM)
Article 10, Volume 30, Issue 2, 2006, Pages 95-107 PDF (0 K)
Authors
Al-Samarai F.R; Al-Anbari N.N; Al-tmimi Y.K
Abstract
A total of 16678 records of age at first calving and ages at next calving , in addition to 14058 records of calving interval belonged to Holstein cows were analysed over period from 1992 to 2003 , at the Nasr Dairy Cattle Station, United Company for Animal Resources Ltd., Al-Soueira ( 50 Km South of Baghdad ). Data was analaysed using General Linear Model within the SAS program to study the effects of some fixed factors on the studied traits . Components of variance for the random effects was estimated by the Minimum Variance Quadratic Unbised Estimation Procedure ( MIVQUE ) , also phenotypic trend was estimated for all traits . The overall means for age at first calving till the age at sixth calving were 48.17 , 62.77 , 77.41 , 91.35 , 105.53 months respectively , and the heritability for the same traits was 0.10 , 0.01 , 0.03 , 0.04 , 0.02 , 0.11 respectively . whereas the overall mean of calving interval and heritability was 458.59 days and 0.07 . The results obtained that there was a significant effect of year of birth on age at first calving , whereas the season of birth was not . All the estimates of heritability were low so it’s reflect the role of environment factors in the traits variation.Phenotypic trend was negative and significant ( p <0.01 ) for age at first calving ( - 1.05 month / year ) and calving interval (- 2.03 day / year ) .

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