The Obama administration’s latest proposal to alter the rules governing livestock marketing contracts drew heaps of praise from some groups and sharp criticism from others.

The U.S. Department of Agri­culture’s Grain Inspection, Packers and Stockyards Administration (GIPSA) last week announced updated regulations to clarify what the agency views as unfair practices and reduce the burden for farmers seeking justice under the Packers and Stockyards Act, said Agriculture Secretary Tom Vilsack.

The so-called "Farmer Fair Practices Rules" will benefit poultry growers who are particularly vulnerable to market risks and concentration in the processor market, Vilsack...