Genetic And Phenotypic Aspects and Trends of Longevity and Lifetime Production Traits in Friesian Cattle in Egypt

A total of 2914 cow records with complete set of all traits, daughters of 66 sires and 427 dams were used. The VCE animal model programs were used to estimate heritability, genetic and phenotypic correlations for longevity and lifetime production traits.Heritability estimates were 0.087, 0.149, 0.159 and 0.101 for LLNO, HL, PL and LLP, respectively, however it were 0.187, 0.176, 0.154, 0.146 and 0.108 for LM305, LTMY, LMYHL, LMYLP and LPHL, respectively. Genetic correlations between longevity traits (LLNO, HL, PL and LLP) were high and ranged from 0.901 between HL and LLP to 0.991 between LLNO and PL. Genetic correlations between lifetime production traits were high and ranged from 0.843 between LMYHL and LPHL to 0.995 between LM305 and LTMY. Phenotypic correlations were less than the corresponding genetic correlations among most traits. Genetic trend over 35 years was favorably positive for lifetime production traits, however it was unfavorably negative for longevity traits. The annual genetic changes were 53.6kg for LM305, 65.5kg for LTMY, 0.031kg for LMYHL, 0.063kg for LMYLP and 0.021% for LLPHL, however the annual genetic changes were -0.080, -0.356d, -4.9d and -4.9d for LLNo., LLP, HL and PL, respectively. Phenotypic trend was unfavorable deteriorating negative for all longevity and lifetime production traits over 35 years, except LMYLP, it was favorably positive.