A crossbreeding program between Ardi Saudi goats (A) with Syrian goats (Damascus, D) was started in 2006 in two experiments (Jouf and Qassim) applying bio-techniques of estrous synchronization and artificial insemination. Breeding does of Ardi goats were randomly divided into two groups and each group was subdivided into two subgroups to be inseminated artificially from semen of elite bucks of the same breed and of Damascus breed. Crossbred does of ½D½A were backcrossed with Damascus bucks to get the genetic group of ¾D¼A and such breeding plan permitted to produce four genetic groups of AA, DD, ½D½A and ¾D¼A in each experiment separately. Data collected were: 1) live body weights and gains at birth and biweekly thereafter
up 24 weeks of age, 2) carcass traits, and 3) meat compositions involving dry matter, crude protein, ether
extract, and ash. The animal models were used to estimate heritabilities and common litter environmental effects‚ while a generalized least square procedure was used to estimate direct additive genetic effects(GI)D. GIA= G −G , direct heterosis (HI), maternal heterosis (HM) and direct recombination effects (RI).
Heritabilities were moderately heritable and ranging from 0.12 to 0.36 for body weights, 0.11 to 0.25 for body
gains, and 0.10 to 0.34 for carcass traits. All estimates of direct additive effects for body weights at 0, 4, 8, 12,
16, 20 and 24 weeks of age were significantly in favour of Damascus goats by 0.260, 1.504, 1.337, 1.505, 1.324,
1.873 and 2.080 kg in Jouf experiment and by 0.548, 1.876, 2.168, 2.975, 2.739, 3.594 and 4.046 kg in Qassim
experiment, respectively. The respective estimates for body gains at interval of 0-4, 4-8, 8-12, 12-16, 16-20, and
20-24 weeks of age were also significantly in favour of Damascus goats by 47, 31, 7, 30, 33, and 28 g in Jouf
experiment and by 47, 35, 22, 42, 18, and 32 g in Qassim experiment. The estimates for most carcass traits were
moderate and significantly in favour of Damascus kids by 6.2 kg for pre-slaughter weight, and 4.2 kg for hot
carcass weight, while the estimates for meat compositions traits were somewhat low and in favour of Damascus
kids relative to Ardi kids by 4.4% in dry matter of the lean and 3.4% in ether extract. The heterotic increments
were mostly significant and ranging from 3.0 to 11.4 % for body weights and daily body gains and 2.4 to 28.1 %
for carcass traits relative to the parental purebreds, while the estimates for meat composition traits were mostly
non-significant although crossbred have shown reductions in moisture, ether extract and ash in meat of the carcass. The maternal heterotic increments in body weights and daily body gains were mostly significant and the estimates ranged from 1.0 to 27.0 %. Direct recombination losses were of little importance for the majority of the traits and they were generally lower than the estimates of direct heterosis.
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