الكفاءة التناسلية المقدرة بمعادلة Tomar وعلاقتها كمتغير مستقل وتابع مع مدة الحياة والحياة الانتاجية في الهولشتاين

Abstract

A total of 17935 Record belonged to 4100 Holstein cows maintained at Nasr Dairy Cattle Station over period from 1987 to 1999 were analyized.The aim is to study the effect of breeding efficiency estimated by Tomar equation as independent and dependent factor on longevity in order to estimate genetic and phenotypic correlations.The General Linear Model within SAS program was used to study the effects of breeding efficiency ,season of birth ,year of birth and parity on longevity and productive life.Component of variance for the random effects was estimated by MIVQUE method. The heritability of longevity , productive life and breeding efficiency were 0.04 , 0.05 and 0.04 respectively.The genetic correlation was negative and significant ( p <0.01 ) between breeding efficiency and each of longevity and productive life , the coefficient being – 0.18 , - 0.17 .The corresponding estimates for phenotypic correlations were – 0.11 and – 0.10