use funds available to carry out the provisions of section 612c of title 7 which are not expended or needed to carry out such provisions, to purchase (without regard to the provisions of existing law governing the expenditure of public funds) agricultural commodities and their products of the types customarily purchased under such section (which may include domestic seafood commodities and their products), for donation to maintain the annually programmed level of assistance for programs carried on under this chapter, the Child Nutrition Act of 1966 [42 U.S.C. 1771 et seq.], and title III of the Older Americans Act of 1965 [42 U.S.C. 3021 et seq.]; and

if stocks of the Commodity Credit Corporation are not available, use the funds of such Corporation to purchase agricultural commodities and their products of the types customarily available under section 1431 of title 7, for such donation.