CBI court judge Shiv Pal Singh, who had convicted Prasad, along with 10 others on December 23, also imposed a fine of Rs one million on him for two cases in the scam.
He was fined Rs 500,000 for each case, failing which he would serve another six months in jail, a CBI counsel said.
The court had convicted Prasad for offences of cheating, along with criminal conspiracy, under the Indian Penal Code (IPC) and the Prevention of Corruption Act.
The scam is related to withdrawal of Rs 8.9 million from the Deogarh Treasury between 1990 and 1994 when Prasad was the chief minister of Bihar.
The 69-year-old RJD supremo, in a written plea on Friday, had sought leniency from the CBI court citing illness and old age, according to his counsel Chittaranjan Prasad.
The RJD went into a huddle immediately after the pronouncement of the sentence.
RJD sources said that the party would appeal against the verdict.
This is the second fodder scam case in which Prasad has been jailed.
He was sent to prison for five years on September 30, 2013.
Prasad was granted bail by the Supreme Court after having spent over two-and-a-half months in jail.