Identifying potentially subfertile toms via a sperm-binding assay

We evaluated the utility of the commercial version of a new sperm-egg binding assay for detection of differences in sperm quality in samples of turkey semen from individual toms. Each sample had a swirl of 2 or more on a scale of 0 to 4. For assays conducted with fresh semen at 4 × 10⁶ sperm per well, values ranged from 0.11 to 12% sperm bound to an extract of perivitelline membrane. Within-male variation averaged 0.17 percentage units, based on three ejaculates per male evaluated. Two experiments compared fertility and hatch for hens after weekly insemination with pooled semen from subpopulations of toms classified as having sperm with LOW or HIGH binding. Average fertility and hatch were lower (P < 0.05) for eggs laid by hens inseminated with semen from LOW toms in one experiment. In another experiment, hen fertility was not different between treatments after insemination during Weeks 32 to 39; however, a sharp decline in hatch was observed only for hens inseminated with semen from LOW toms after 40 wk of age. With semen from HIGH toms, hatch remained at ≥80%. For these experiments, ∼7% more poults were obtained from hens inseminated with semen from HIGH toms. We demonstrated that the sperm-egg binding assay detects differences in sperm quality between individuals, and these differences influence fertility.