Summary Two comparable groups of 10 bulls each were selected. Both were fed a practical ration made up of common, natural feeds which supplied plenty of vitamin E for normal reproduction of rats. To determine whether or not additional vitamin E in the form of solvent process wheat germ oil would benefit the reproductive performance of bulls used extensively for artificial insemination, each of the bulls in one group received one ounce daily of the wheat germ oil during an experimental period of one year. Over 1,250 semen samples were collected from the 20 bulls, and over 8,200 cows were artificially inseminated during the experiment. A comparison of the results from the two groups warrants the following statements: The feeding of one ounce daily of solvent process wheat germ oil in addition to the normal ration did not: 1. Increase the volume of semen produced by the bulls; 2. Increase the spermatozoa concentration in the semen; 3. Improve the motility of the spermatozoa; 4. Shorten the time required for service; 5. Decrease the number of semen ejaculates which were discarded as being of too poor quality for use in artificial insemination; 6. Improve the fertility of the bulls to which it was fed; 7. Nor prevent two bulls from decreasing in fertility to such low levels as to force their withdrawal from use in artificial insemination. A study of the seasonal effects showed a highly significant decrease in percentage of motile spermatozoa during the early spring months and a highly significant difference between months in spermatozoa count. The lowest average count was found in August, but there was no significant difference in fertility of the bulls from month to month.