Semen characteristics of bucks were evaluated for five genetic groups produced from a crossbreeding project involving Spanish breed called V-line (V) and Saudi Gabali (G) rabbits. For the first two generations of this project, volume of ejaculate, sperms abnormalities, living sperms, dead sperms, sperms concentration, motility of sperms and libido of bucks of these genetic groups were evaluated for 195 ejaculate given by 74 bucks. Seasonal variations in semen ejaculated by bucks and effect of litter size in which the buck was weaned were also investigated. Sperms concentration (being 525, 543 and 488 sperm in 0, 1st and 2nd generation, respectively) and motility of sperms (being 47.4, 68.1 and 79.9 % in 0, 1st and 2nd generation, respectively) increased or improved from the parental generation to the two subsequent generations. Significant improvements in semen parameters of crossbred bucks than in purebred ones were recorded in terms of sperms concentration and percentages of motile sperms, abnormal sperms and dead sperms. Most semen parameters of V-line bucks were better than in G rabbits. Lower volume of ejaculate (0.56 ml) in addition with lower motility rate of sperms (50.6%) was noticed in the Gabali rabbits than in the other genetic groups. Autumn and winter recorded the best semen parameters in terms of sperm concentration, motility of sperms, abnormal sperms and libido relative to spring and summer. The estimates during autumn, winter, spring and summer were 537, 564, 405 and 437 for sperms concentration (sperm multiplied by 106 per ml), 72.0, 68.5, 61.6 and 58.4% for motility of sperms, 7.6, 5.3, 9.6 and 10.2% for abnormal sperms and 4.03, 3.38, 3.51 and 3.04 for libido. Moderate litter size of 6 or 7 born by the doe gave the lowest abnormality rate of sperms in the semen of bucks (about 7.8%) and the largest volume of ejaculate (about 0.68 ml) associated with the highest sperm concentration (about 522 sperm multiplied by 106 per ml), sperm motility (about 78%), living sperms (about 91.5%) and libido (about 4%). |
