Genetic Assessment for some Productive and Fertility Traits Using Maximum Likelihood (REML) Of Friesian Cows in Egypt

This study aimed to evaluate the genetic improvement program of the Friesian  cows. SAS program was used to calculate averages and significant effect, and (REML) program was used to estimate genetic parameters for productive traits lifetime milk yield (LTMY), daily milk yield (DMY), Lactation Length (LL) and Lactation number complete (LNC), and fertility traits days open (DO) and calving interval (CI). The least square means of LTMY, DMY, LL, LNC, DO and CI were 17546 (Kg), 12(Kg), 304 (d), 3.5 (lactations), 78 (d) and 379(d), respectively. The effect of the month, year of calving and age at first calving (AFC) were significant for all the traits except, the farm was non-significant to DMY. Estimates of the heritability (h2a) were 0.09, 0.44, 0.24 and 0.34 for LTMY, DMY, LL and LNC, respectively, whereas 0.13 and 0.17 for DO and CI, respectively. High h2a of productivity traits, particularly DMY, emphasized the possibility of achieving a significant rate of genetic improvement in this trait through selection program. The genetic correlations were positive ranging from 0.02 to 0.76 , except CI with (DMY, LL and LNC ) were negative and ranging from -0.07 to -0.76 . The highest genetic and phenotypic correlation between DMY and LTMY. The low genetic value of these fertility traits reflected the lack of patients' genetic advancement for these traits while, phenotypic correlation estimates were positive except reproductive traits with some productive traits. Repeatability estimates are few and close to the heritability value due to the small presence of permanent environmental variation, confirming the unpredictability of the cow from its current records of fertility traits.