Association of genetic polymorphisms with fertilization in the chicken.

Associations between fertilization rate and genotypes at four polymorphic loci were studied in three relatively non-inbred populations of Light Sussex chickens. In sires the genotypes tested were at theB blood-group locus only; in dams, at theB locus and three egg-white loci. Data were available for purebred matings of related substrains 6D and 6F and the ancestor strain 6 from which they were derived and for crossbred matings of 6D and 6F by two related Rhode Island Red/New Hampshire strains.In analyses of variance by dam genotypes within sires, no locus or combination of loci had a significant effect on fertilization rate. In analyses by sire and damB blood-group genotypes, no significant effects were found in 6F. SireB genotypes showed a very significant effect (P<0.001) on fertilization rate in 6D, and in 6. The latter effect was not fully acceptable since there was a significant (P<0.02) sirex damB genotypes interaction effect in 6. This interaction took the form of a lowered fertility in matings where sire and dam had the sameB genotype. The significant main effect in 6D was due to significant differences between the fertilization rates of the three most frequent sire genotypes. The same differences were not found in the other two strains. Similarly, significant sireB genotype differences in the Rhode Island Red/New Hampshire mates of 6F were not repeated in those of 6D.Combination of this result with those from our previous work with embryonic mortality in these strains is still insufficient fully to explain the continued segregation of four alleles at theB blood group locus.