The proportion of beef bulls in Sweden with mature spermiograms at 11-13 months of age.

Semen samples collected postmortem from 142 yearling beef bulls (11-13 months old) of three different breeds (Charolais, Hereford and Simmental) were examined to evaluate the proportion of bulls with mature spermiograms. Before slaughter, testes and epididymides were clinically examined and scrotal circumferences were measured. Aliquots of the cauda epididymal contents taken postmortem were used for sperm morphology examination. Sperm head morphology was studied in dry smears stained with carbol-fuchsine. For each preparation, 500 spermatozoa were counted in each smear under light microscope (x 1000). The presence of proximal cytoplasmic droplets, abnormal acrosomes, detached heads and abnormalities of the midpiece and tail were recorded in wet preparations of formol-saline-fixed spermatozoa. For each preparation, 200 spermatozoa were counted in each preparation under a phase-contrast microscope (x 1000). The abnormalities were classified according to a classification system developed by Bane (1961). Morphological abnormalities were recorded as a percentage of the total number of counted spermatozoa. Criteria for a spermiogram to be considered mature included <15% abnormal heads and <15% proximal droplets. According to this definition approximately 48% (68 of 142) of the examined bulls were considered mature. The bulls in this study represent approximately one-fifth of the total amount of performance-tested beef bulls in Sweden during 5 years. Our results indicate that only less than half of the Swedish yearling beef bulls at the testing station appear to have a mature spermiogram at the time they are offered for breeding purposes.