Frequency of occurrence of diploid bovine spermatozoa.

Abstract

semen smears was twice the normal level. Similar observations on bovine spermatozoa have been made by Gledhill (1964, 1965) who also studied such cells by ultraviolet fight absorption and by interferometric mass determinations. All three of the techniques used by Gledhill support the hypothesis that the exceptionally large and densely staining sperm nuclei are diploid. The incidence of diploid spermatozoa is low, is characteristic of the semen of individual bulls and may be genetically determined. This paper presents evidence on the inci¬ dence of diploid spermatozoa in a special population of bulls and suggests the reality of genetic influence on the incidence within this population. The data are derived from the examination of single Feulgen-stained semen smears from eighty bulls from the San Juan Basin Branch Experiment Station, Hesperus, Colorado. Most of the bulls are involved in an inbreeding experiment and include inbred Hereford lines, line crosses, an outbred control line, some breed crosses and a few dairy bulls. Inbreeding coefficients in the inbred lines range from 0-14 to 0-50. The diploid spermatozoa in 1000 spermatozoa were counted on each smear with the exception of two thin smears, where the counts