As rendering services decline in Iowa, swine, turkey, broiler, and egg producers are faced with rapidly increasing costs for safe disposal of an estimated 43,000,000 pounds of dead pigs and poultry each year. Land filling of animal carcasses has prompted growing pub­ lic concern about environmental impacts, and some landfill operators now impose constraints such as freezing before accepting such wastes. Another disposal approach, incineration, can cost over 4 cents per pound, and it often results in serious air pollution.