Sadly, Big Brown be retired from racing before the end of 2008. The reason is simple: he can generate far more revenue at significantly lower cost by performing stallion duties, as Alex Brown explains:
Based on Smarty Jones’s [ed: another early retiree] numbers of 2006, each year Big Brown will earn $100,000 x 112, $11.2 million. ... From an investment standpoint — and Big Brown’s owners are investors — to keep Big Brown in racing beyond his 3-year-old career, he would need to earn more than $11.2 million a year plus the additional costs of insurance as a racehorse versus insurance as a stallion. Obviously the economic decision has to be to retire Big Brown.
Go on over to The Rail to see the basis for this calculation.