We studied fertility traits in Japanese quail by testing the hypotheses that the offspring produced from high fertility parents will also express high fertility and that the rate of egg fertilization can be correlated to sperm motility traits.
Japanese quail (45 x 350 male x female; n = 395 randomly selected from primary breeder flock) were naturally mated and the numbers of holes made by sperm in the egg the perivitelline layer (HolesIPVL/4.71 mm2) of the vitelline membrane, the percentage of fertile eggs, the female fertile period, sperm loss rate (during fertile period), and sperm motility parameters (motile sperm, rapid sperm, progressively motile sperm, velocity straight line, velocity curvilinear and velocity average path) were estimated and analyzed. The percentage of fertile eggs, fertile period and sperm loss rate were explained by HolesIPVL (multiple regression analysis by SPSS). The percentage of fertile eggs was highly correlated with HolesIPVL on the male (r2=0.70, P<0.000; HolesIPVLMale = 17.4±2.5 mean±SD) the female side (r2=0.45, P<0.000; HolesIPVLFemale = 18.2± 6.1) but there was no relationship between HolesIPVL and sperm motility parameters. Based on HolesIPVL, the males (top and bottom 25%) and females (top and bottom 10%) were ranked into low and high fertility categories. The mean HolesIPVL were 22.1± 2.0 & 25.9± 2.3 for high fertility males and females and 14.4±2.2 &12.2±3.9 low fertility males and females respectively. High fertility males and females were then mated to produce offspring that were mated (20 x 20 male x female; n = 40) when 14-20 weeks old to determine HolesIPVL and the same fertility traits as in the parents. The mean HolesIPVL was 54.3±47.4. Whereas the mean HolesIPVL for the parents at the comparable age (16 weeks) was 22.1± 15.7. There was no correlation between the percentage of fertile eggs (r2 = 0.24, P>0.05) or sperm motility parameters (r2 =0.34, P>0.05) and the HolesIPVL.
We conclude that fertility in offspring may be improved by selecting for high HolesIPVL but measures of fertility expressed by the female are independent of sperm motility traits.