Per 1860 Slave Inhabitants, Frederick Watkins had the following male slaves that were age 12 and above-
1-60, 1-50, 5-40, 1-35, 1-30, 6-25, 8-20, 2-18, 1-16, 2-15, 1-14, 1-13 and 3-12

I don't know what ages qualified for service, but the above totals 33.