The world’s largest beef producer, Brazil’s JBS announced its board agreed to boost its capital by as much as 3.48 billion Real (2.15 billion US dollars) through a private placement with Brazil’s state economic and social development bank.   BNDES, as the bank is known, will convert into stock the bonds that it bought from Sao Paulo-based JBS in December 2009 to help it finance takeovers of Pilgrim’s Pride Corp. and Bertin SA.   At the time, JBS said the bonds would be convertible into…