ABSTRACT
A crossbreeding program between Aradi Saudi breed (A) with Syrian Damascus
breed (D) was practiced for three years to produce ½D½A genotype. A total number of
191 ejaculates collected from 42 bucks fathered by 12 sires and mothered by 42 dams
were used to evaluate semen characteristics of bucks. An animal model was used to
estimate heritabilities and permanent environmental effects and variance components
obtained by this animal model were used to solve the corresponding mixed model
equations, obtaining solutions for the genetic group means and their standard errors. A
generalized least square procedure was used to estimate direct additive genetic effects
and direct heterosis. Heritabilities obtained for semen characteristics were mostly
moderate or low and ranged from 0.04 to 0.16. Direct additive effects were in favor of
Aradi bucks by 11.4% for ejaculate volume, 4.2% for live sperms and 5.7% for total
sperm output relative to Damascus bucks, while a reverse trend in favor of Damascus
bucks was recorded for sperms concentration (-3.6%), total motility of sperms (-
15.0%), and dead sperms (24.5%). Positive and significant estimates of direct heterosis
for volume of ejaculate (16.3%), total sperms output (12.5%), sperms concentration
(5.4 %) along with a negative estimate recorded for abnormal sperms percentage (-
3.3%) were favorable for crossbred bucks; i.e. crossing Saudi Aradi does with
Damascus bucks was associated with an increase in ejaculate volume (0.245 ml,
P<0.01) and sperm concentration (0.15 x 109 per ml, P<0.05) along with a reduction in
percentage of abnormal sperms (-0.45 %, P<0.05).