There is growing demand in Iowa for pigs raised outdoors or in a deep-bedded system without the use of antibiotics, growth promotants, or animal by-products. Currently, most producers selling naturally-raised pork, market their animals to a company that requires adherence to the Animal Welfare Institute’s (AWI) Animal Welfare Standards. One of the key components of these standards is the prohibition of farrowing crates. While a pasture farrowing system is effective during spring, summer, and fall, an alternative system is needed to farrow pigs in the winter for the naturally-raised pork market.

There are a variety of farrowing systems currently being used during cold weather to farrow pigs for the natural pork market. In general, all rely upon a primary heat source capable of maintaining a room temperature of at least 50ºF and auxiliary heat sources (heat lamps, bedding pack, hovers) to create a warmer microclimate for the young pigs. The use of adequate bedding and a design in harmony with the natural instincts of the pigs is key to the success of the example systems. A final critical consideration is a breeding program that insures sows in a particular room farrow within a short time frame (7 days or less) of each other to facilitate subsequent group lactation.

With an increasing interest in winter farrowing to meet the naturally-raised pork market, Iowa State University embarked on a project funded by the Leopold Center to demonstrate alternative farrowing systems in cold weather. In 2002, a 150,000 Btu/hr radiant heater tube was purchased and installed in an existing building on the Allee Demonstration Farm near Newell, IA. Modified A-frame farrowing huts designed for pasture farrowing were set-up in a double row down the center of the building. In the winter of 2002/2003, 36 litters were farrowed in this system. A total of 293 pigs were weaned for an average of 8.14 pigs/litter. Total energy expense for producing those 293 pigs was $4.94/pig weaned. In the winter of 2003/2004, 20 litters were farrowed and a total of 132 pigs were weaned. Weaning averages for 2003/2004 was 6.6 pigs/litter and an associated energy expenses of $7.73/pig weaned. The 2003/2004 winter was more severe. Over the two winter farrowing periods, 425 pigs were weaned from 56 litters for an average of 7.59 pigs/litter. Average energy cost for producing those animals was $5.81/pig weaned.