Identifying potentially subfertile toms via a sperm-binding assay

We evaluated the utility of the commercial version of a new sperm-egg bindi ng 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 scal e of 0 to 4. For assays conducted with fresh semen at 4 x 10(6) sperm per w ell, values ranged from 0.11 to 12% sperm bound to an extract of perivitell ine membrane. Within-male variation averaged 0.17 percentage units, based o n three ejaculates per male evaluated. Two experiments compared fertility a nd hatch for hens after weekly insemination with pooled semen from subpopul ations of tom 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 fer tility was not different between treatments after insemination during Weeks 32 to 39; however, a sharp decline in hatch was observed only for hens ins eminated with semen from LOW toms after 40 wk of age. With semen from HIGH toms, hatch remained at greater than or equal to 80%. For these experiments , similar to 7% more poults were obtained from hens inseminated with Semen from HIGH toms. We demonstrated that the sperm-egg binding assay detects di fferences in sperm quality between individuals, and these differences influ ence fertility.