(even though Chapter 12 does not create a bankruptcy estate separate from the debtor, Chapter 12 debtor may treat postpetition income taxes triggered during pendency of case as administrative expense under 11 U.S.C. Sec. 503; debtors' pre-petition sale of slaughter hogs constitute sale of a "farm asset" that is "used in the debtor's farming operation under 11 U.S.C. Sec. 1222(a)(2)(A) - dissenting opinion on this point based on plain language of the statute and that 11 U.S.C. Sec. 1222(a)(2)(A) better analyzed by Internal Revenue Code capital gain provision than by Bankruptcy Code provision that operates in different context; marginal method is the correct method to determine the allocation of taxes between priority and non-priority claims under 11 U.S.C. Sec. 1222(a)(2)(A) - dissent on this point noted that U.S. Supreme Court has rejected the notion that the Bankruptcy Code is a "remedial statute" that should be construed liberally in favor of debtors).