Answer by taking a quote from the following article:

Francis Piol Bol Bok (born February 1979), a Dinka tribesman and native of South Sudan, was a slave for ten years but is now an abolitionist and author living in the United States. On May 15, 1986, he was captured and enslaved at the age of seven during an Arab militia raid on the village of Nyamlel in South Sudan during the Second Sudanese Civil War. Bok lived in bondage for ten years before escaping imprisonment in Kurdufan, Sudan, followed by a journey to the United States by way of Cairo, Egypt. Bok was aided by people of diverse cultures and faiths in his journey to freedom.

Seven-year-old Bok was captured by Giemma, a member of the slave hunting militia, who forced him to join a caravan of slaves, stolen produce, livestock and wares that the militia had captured in their raid of the Dinka settlement. When the members of the militia split up to return to their homes, Bok was taken by Giemma. Upon arriving at Giemma's residence, Francis was beaten by his captor's children with sticks and was called abeed. The word literally means "slave" and the stereotype is that of an inferior, demeaned, Negroid race. Francis was given quarters in a hovel near the pens of Giemma's livestock.  Bok began a ten-year period of slavery at the hands of Giemma and his son Hamid. He was forced to tend the family's herds of livestock. He had to take them to pastures in the area and to local watering holes, where he saw other Dinka boys who were also forced to tend herds of livestock. He began to suspect that his life was going to change forever and that his father was not going to be able to save him. His attempts to speak to the other Dinka boys were futile, as they were speaking Arabic, which he could not understand; they also seemed afraid to speak to him.  According to Bok, as he grew older, Giemma and Hamid began to place more trust in his abilities as a herdsman. Care of the cattle, horses and camels was passed to Bok and he was able to spend more time alone with the animals. Previously he had been under the careful supervision of Hamid and sometimes Giemma. In addition to having him serve as his slave, Giemma forced Francis to convert to Islam and to take the Arabic name of Abdul Rahman, meaning "servant of the compassionate one." In his autobiography, Francis states that although he was forced to convert to Islam, that he never stopped praying to God for strength to get him through his ordeal.  Bok tried twice to flee from slavery at the age of 14. The first instance happened early one morning after he had been sent out with the cattle. Bok blindly ran down a road for several miles before he was captured by one of Giemma's fellow militia members. Giemma's peer returned Francis to the Giemma's compound, where he was beaten with a bullwhip. Bok attempted to escape once again just two days later, when he fled in the opposite direction of his previous escape. He once again fled for several miles, this time keeping to the forest. He stopped for water at a local stream crossing, where he was spotted by Giemma who happened to be there as well. Giemma forced Francis back to his home, this time promising to kill him. Francis was beaten again, but Giemma chose not to kill him, as Francis had become too valuable to the family as a slave.

What else was he forced to do?
Care of the cattle, horses and camels