The Revenue Reconciliation Act of 1990, Pub. L. No. 101-508, 104 Stat. 1388 (1990), has amended the eligibility requirements for expense method depreciation for property placed in service after 1990. Id., Sec. 11801. Before the amendment, expense method depreciation was limited to "Section 38 property," I.R.C. § 48(a), which was originally enacted for purposes of investment tax credit eligibility and which excluded horses from eligibility for investment tax credit and thus from expense method depreciation. I.R.C. § 48(a)(6).