Chuck,
The slaveowners knew very well the significance of the slave's names, and that is why they do not appear in the 1850-1860 censuses. The idea of listing the slaves' names had become a politically-charged issue. Abolitionist congressmen and their sympathizers wanted slaves to be listed in the same detail as free persons, and the southern slaveocracy wanted data about slaves suppressed from the public record.

The following brief quote comes from the University of virginia website, "Valley of the Shadow" (full discussion can be read at the link, below):

"For the 1850 census, Northern representatives in Congress proposed that enumerators collect as much detailed information on slaves as they did on free persons. Southern congressmen staunchly opposed such revisions, and instead sought to limit inquiries on slaves so as to prevent the collection of data which would allow for comparisons between free and slave labor or between the quality of black and white life. . . [William] Seward and his colleagues proposed that the 1850 questionnaire used by census-takers inquire into a slave's name, age, sex, color, and place of birth. It also sought information on the number of children borne by slave women. Southern congressmen revolted against such proposals, and they successfully offered amendments which removed from the forms questions regarding slaves' names, place of birth, and number of children born to slave women. As a result, the 1850 census only noted the age, sex, and color of each slave. The 1860 census followed suit."

Census-takers were not given a choice. Their instructions for the 1860 census explicitly stated: "In the case of slaves, numbers are to be substituted for names."

David

P.S. And, yes, the slavemasters often listed mules and horses by name on estate inventories, in the same lists with their slaves, tools, household furniture, and other property!