Cuiba, Brazil - Nivaldo Inacio da Silva has a word to describe what it's like to wake up at 6am, strap on a hard hat and endure suffocating 38 degree Celsius heat on the construction site of one of Brazil's new World Cup soccer stadiums: "Freedom." Da Silva is one of 25 men at the site who, in their previous jobs, worked in conditions that were classified as slave labour by the Brazilian government. They are now helping to build the stadium in the western city of Cuiaba as part of a state-sponsored programme that trains former "slaves" in skills like carpentry and helps insert them into the regular workforce. Like several of the men, Da Silva said he was lured into accepting a job as a farm hand, and then forced to pick cotton seven days a week from dawn to dusk in return for pay he never received. He had to forage or hunt for food. He said he was unable to escape because of the farm's isolation, and left only after a co-worker managed to flee and alert the authorities. Now he and the other workers say they are proud to be front and centre in Brazil's preparations to host the 2014 World Cup. "I'm happy. I have the freedom to do what I want now," said Da Silva, 44, who lives with the other workers in temporary on-site housing provided by the company - and has weekends free. "Before, we had to sleep in the jungle. Now, we have a good work schedule, good food. There is nothing to complain about because everything got better in our lives." The story of how Da Silva and the others arrived at the site is rooted in Brazil's economic challenges, past and present. Brazil imported more African slaves than any other country in the Americas, mainly to cut sugarcane. While slavery was formally abolished in 1888, there are still pockets of Brazil, especially on farms and in areas where the Amazon jungle is being razed, where working conditions are frighteningly similar to those in the 19th century. Even in Brazil's biggest and most modern city, Sao Paulo, authorities often discover workers in slave-like conditions in sweatshops producing textiles and clothes. More than 2 600 people were "rescued" from slave labour in 2010, the labour ministry said. Brazil's government has made the problem a top priority over the past decade, and expanded the definition of slavery in 2003 to include both forced labour and degrading working conditions - a broader definition than many countries, said the International Labor Organisation. Government programmes such as the one that placed the workers at the Cuiaba stadium, which included six months of on-site training, are critical to ensuring that slavery ultimately disappears for good in Brazil, said Valdiney Arruda, the superintendent at the labour ministry in Mato Grosso state. "The biggest challenge is often to prove to these people that they are capable" of working dignified jobs, Arruda said. "How do you leave behind a whole lifetime in just six months?... It's not easy, but they're doing it." "Now I have a job" When the men first arrived at the stadium site last April, all of them were functionally illiterate, said Simone Ponce, a spokesperson for the consortium of companies building the stadium. Many were unaccustomed to following even basic instructions, and struggled at first in a classroom setting as teachers tried to teach them everything from basic reading skills to construction techniques to how to manage their money. "Some of them got frustrated, and started saying things like 'Being a servant was OK for me'," Ponce said. “Others were just afraid because they had never been treated well by an employer." Still, they stuck with it. Of the 26 who enrolled in the programme, only one dropped out and went back home to Brazil's northeastern region. The men said they quickly saw the value of what they were being taught. Durval Fernandes da Silva, 38, said he was one of 20 siblings and never had the opportunity to go to school. "All I did (before) was cut sugarcane," he said. "Now I have a job. I've learnt a lot and I learn more every day." The programme has been just as useful for the companies. Many Brazilian cities face a severe labour shortage as years of robust economic growth have pulled workers away from hard labour such as construction. The problem is so pronounced in Cuiaba, which is experiencing a boom from soy, that the consortium has been forced to alter its plans by using more preassembled pieces in the stadium's construction. "We've trained these men ourselves, and as a result we've received a better quality of labour," Ponce said. "They're like family now, so they're more likely to stay than others might be. It's almost like a human resources programme." "What's happened here is not charity," said Arruda, the state labour ministry official. "It's an exchange. The company gets labour, and society gets productive people." The workers' classes ended in January, and they are now considered regular full-time employees, working alongside some 600 others. They earn a salary of 816 reais ($480) a month - the same as their co-workers and 30% above Brazil's minimum wage - plus free room and board. The learning hasn't stopped, though. Ponce proudly shows a company photo album containing pictures of when they took Fernandes da Silva to a movie theatre for the first time in his life - he was scared of the escalator, but enjoyed the movie. She said the consortium is still trying to teach the workers basic things like going to a dentist when a tooth hurts instead of just ripping out the tooth. "We've changed the lives of 25 people, and God willing we'll change the lives of their kids," Ponce said. "We've learnt a lot from them, too."