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Two parallel schemes of crosses were practised involving the Spanish maternal line called V-line (V) and Saudi Gabali (S) rabbits. The first scheme began by crossing Saudi Gabali bucks with V-line does to get the F 1 cross ( 1 2 S 1 2 V), then does of this F 1 were backcrossed with bucks of V-line to get 3 4 V 1 4 S, then the progenies of the backcross were inter se mated to get ( 3 4 V 1 4 S) 2 , followed by two more generations of inter se mating of ( 3 4 V 1 4 S) 2 to get a new synthetic maternal line named Saudi 2. The second scheme began by crossing V-line bucks with Saudi does to get the F 1 cross ( 1 2 V 1 2 S), then does of this F 1 cross were backcrossed with Saudi bucks to get 1 2 S 1 2 V, then progeny of this backcross were inter se mated to get ( 3 4 S 1 4 V) 2 , followed by two generations of inter se mating of ( 3 4 S 1 4 V) 2 to form a new synthetic paternal line named Saudi 3. A generalised least-square procedure was used to estimate differences between lines in direct and maternal additive effects, direct and maternal heterosis, and direct recombination losses. A total number of 2497 ejaculates of 642 bucks were evaluated for ejaculate volume (VE), pH of semen, sperm concentration (SC), percentage of motile spermatozoa (MS), percentage of spermatozoa with abnormal form (AS), percentage of dead spermatozoa (DS) and libido score (LS). The estimates of direct additive effect for DS (14.2%), SC (12.4%) and AS (12.0%) were moderate and favourable to Saudi rabbits. Maternal additive effects for VE (11.7%) were in favour of genes of V-line carried by the dams of bucks, while these estimates were in favour of Saudi genes for DS (18.6%), AS (13.2%), MS (10.8%) and SC (10.0%). Positive estimates of direct heterosis recorded for SC (13.5%), VE (10.6%) and MS (10.5%) and the negative estimates recorded for AS (221.5%) and DS (220.3%) were moderate and well disposed to semen parameters of crossbred bucks. Positive estimates of maternal heterosis for VE (24.0%), MS (21.8%), SC (10.3%) and LS (10.2%) of bucks, and the negative estimates for percentage of DS (214.7%) and AS (29.6%) were also significantly favourable. Estimates of direct recombination losses for the majority of semen traits were always not significant.

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A total of 78 rabbits representing two genetic groups of V-line and crossbred of V-line x Saudi Gabali were used to evaluate dietary treatments containing discarded dates (DD) for post-weaning growth performance‚ feed consumption and conversion‚ carcass characteristics, caecal parameters, and blood constituents. In the control diet (C), no DD was added‚ while in the other diets DD were incorporated to replace partially barley‚ wheat bran‚ molasses and corn by 15% (D15 diet) or 30% (D30 diet). Feed conversion ratio at interval of 4-12 weeks was significantly in favour of the control diet. Carcass traits and caecal parameters were not significantly affected by any of the 3 dietary treatments. Total caecal bacterial count was significantly increased in favour of rabbits fed D30. Crude protein, ether extract and ash in the lean were in favour of the diets containing 15 or 30% DD; indicating an improvement of 5.3 or 3.9% in crude protein and 7.3 or 14.4% in ash relative to the control diet, respectively. Rabbits fed D30 recorded a significant decrease in the plasma cholesterol. Crossbred rabbits were heavier in body weights and gains than that of the V-line rabbits. Feed conversion ratios were in favour of V-line rabbits. Fat in carcass and meat to bone ratio in crossbred rabbits were significantly higher than that in V-line rabbits, while percentages of the lean and bone in V-line carcasses were higher. Caecal bacterial count in crossbred rabbits was lower than that in V-line rabbits. Carcass traits, tissues compositions, caecal parameters and blood constituents were significantly affected by interaction of dietary treatments with genetic groups, while most of the lean constituents were not affected. Crossbred rabbits fed D30 conversed feed lesser (2.57) than crossbred rabbits fed the other two dietary treatments since feed conversion ratio was 2.48 for C diet and 2.49 for D15 diet. But‚ V-line rabbits fed C diet conversed better (2.95) than V-line rabbits fed D15 or D30 since feed conversion ratio was 3.29 for D15 and 3.04 for D30.