Abstract
An experiment was conducted to determine how many spermatozoa must be examined on a single bull semen smear to obtain reliable data on the proportion of morphologically abnormal spermatozoa found on that smear. Five hundred spermatozoa on each smear were examined and classified as to structure. The data were recorded in units of 100 spermatozoa. The results showed that the proportion of abnormally-formed spermatozoa calculated on the basis of the examination of a single unit of 100 spermatozoa was as reliable as the ability of a single investigator to make two slides from the same ejaculate of semen and to examine 500 cells on each one. Also, the data showed that improvement in the reliability of making the morphological classification of spermatozoa was rapid as an investigator gained experience. Copyright © . .