Anheuser Busch InBev NV said on Wednesday that a derivatives gain pushed up its net profit sharply in the first quarter, helping offset weak U.S. demand for the group's beers and the impact of a strong dollar on revenue from the rest of its global beer empire. AB InBev, the world's largest brewer, said net profit jumped to $2.68 billion in the three months to end-March from $1.37 billion in the same period a year ago.