الفهرس 
Effect of year of parturitionOnly 14 pages are availabe for public view
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Abstract
The objectives of the present study evaluation phenotypic and
hereditary factors related with direct and maternal genetic effects on
productive traits (ten-month milk yield (10 MMY), ten month fat yield
(10 MFY), ten month protein yield (10 MPY), lactation length (LL) and
days dry (DD) and reproductive traits (age at first parturition (AFP), days
open (DO) and calving interval (CI), for Friesian cows, kept at Sakha
Farm. A total of 2166 histories of Friesian cows’ progeny of 92 sires and
698 dams, during the period from 2014 to 2020 were used.
Actual means of 10 MMY, 10 MFY, 10 MPY, LL and DD were
2809 kg, 102.31 kg, 79.14 kg, 294.11 d and 122.07. Actual means of
AFP, DO and CI were 32.89 mo., 141.22 d, and 414.87 d, respectively.
The present results concluded that the maternal h2 estimates for
milk yield and itis composition reflected the ability to achieve a plausible rate of genetic improvement for milk traits. Also, Due to minor quantity of additive motherly genetic effects for LL, DD, AFP, DO and CI), it could be decided that the additive maternal genetic effects and the covariance between additive maternal and direct genetic are very little influence to the phenotypic variance of LL, DD, AFP, DO and CI.