Tatar of "fl394 normal records of Friesian cows in first lactation sired by 146
d buus colrecte~ from Sakha Farm, Ministry of Agriculture. Egypt during the period from
1 ~7O- to 1<993< were used in this study. The data were used to estimate; the effects of
non-genetic aad genetic (sire) factors on total milk yield (TMY) and some reproductive
_ tFaits, namely days open (DO), number of service per conception (NSPC) and age at
- first cawing (AFC), and to estimate genetic and phenotypic parameters for the
previous traits. Data were analyzed using linear mixed mode] of Harvey's (1990). The results obtained could be summarized as follows:- The actual means of TMY. DO, NSPC and AFC were 339t.9 kg, 190.7 days. 2.2
service and 31.8 month, respectively. Coefficients of variation of TMY and some
reproductive traits (DO, NSPC and AFC) were 42.8% and (34.7%, 59.3% and
16.8%), respectively. Mo:efh,of calving had significant (P< 0.05) effect on days open. while, non significant
effeets en numb.er of servlce per conception, age at first calving and total milk yield. Year of calving, had highly significant (P< 0.01) effect on total milk yield and of
reproductive traits under the presenf investigation. The sire had highly significant (P< 0.01) effects on total milk yield and days: open
and only significant (P< 0.01) effects on number of service per conception. While,
non significant effect on age at first calving. The sire variance component (cr²s) were
3.62%,6.13%,2.43% and 1.30% fbrTMY, DO, NSPC and AFC. respectively. The estimates of heritability of total milk yield and reproductive traits of the cows at
their first ",arity (llased on parental half-sibs methods) were 0.15. 0.25, 0.10 and
0.Q5 for TM'l, DO, NSPC and AFC, respectively. O. Gel1letic correlations- between reproductive traits studied were positive and
significant (P< 0.0.1), except NSPC with AFC it was negative and significant (P<
0.01). Phenotypic correlations between some reproductive studied traits were showed
positive and significant (P< 0.01) values. Environmental correlation between reproductive traits studied were positive and
highly significant (P< 0.01).