Genetic analysis for semen traits in a crossing program of Saudi Aradi with Damascus goats

Abstract

A crossbreeding program between Aradi Saudi breed (A) of goats with Syrian Damascus breed (D) was practiced for six years in two experiments (dairy experiment in Jouf and meat experiment in Qassim) applying bio-techniques of estrous synchronization and artificial insemination. The breeding plan permitted to produce four genetic groups of AA, DD, ½D½A and ¾D¼A in each experiment separately. A total number of 1800 ejaculates collected from 298 bucks were evaluated for volume of ejaculate (EV), pH, sperm concentration (SC), total motile sperm (TMS), total sperm output (TSO), percentages of motile (MS), live (LS), abnormal (AS) and dead sperms (DS). Animal models were used to estimate the heritabilities and permanent environmental effects, while a generalized least square procedure was used to estimate individual additive genetic effects, individual heterosis, maternal heterosis and individual recombination effects. Heritabilities for most semen characteristics were low or somewhat moderate and ranging from 0.08 to 0.23, while the permanent environmental effects were slightly higher than the respective heritabilities since the estimates ranged from 0.10 to 0.29. Estimates of individual additive effects for SC, TMS and TSO were in favour of Damascus bucks relative to Aradi bucks by 0.2, 0.43 and 0.44×109 per ml in the dairy experiment and by 0.08, 0.13 and 0.11×109 per ml in the meat experiment, respectively. Significant individual heterotic improvements (with a range of 4.9–26.5%) were recorded in the dairy and meat experiments for EV (0.075ml vs. 0.085ml), SC (0.25×109 per ml vs. 0.11×109 per ml), TMS (0.275×109 per ml vs. 0.125×109 per ml), and TSO (0.33×109 per ml vs. 0.155×109 per ml), associated with significant reduction in percentage of DS (5.5% vs. 1.55%). Crossbred dams showed significant maternal heterotic improvements in semen of their crossbred bucks in both dairy and meat experiments for EV (0.058ml vs. 0.055ml; P<0.05), SC (0.15×109 per ml vs. 0.09×109 per ml; P<0.05), TMS (0.225×109 per ml vs. 0.085×109 per ml; P<0.05), and TSO (0.58×109 per ml vs. 0.115×109 per ml; P<0.01), associated with favourable significant increases in MS (3.3% vs. 4.05%; P<0.05) and LS (3.7% vs. 2.25%; P<0.05) along with a reduction in percentage of DS (4.3% vs. 2.25%; P<0.05); the estimates ranging from 3.3 to 34.1%. The estimates of individual recombination losses for most semen parameters were favourable and non-significant.