Summary and Implications
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 most of the spring, summer, and fall, an alternative system is needed in order 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, confined space) 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 hogs 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.
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 62 ft 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.
Iowa State University
Lammers, P. and Honeyman, Mark S.
"Alternative Winter Farrowing Demonstration Project: A Progress Report,"
Animal Industry Report:
AS 650, ASL R1968.
Available at: https://lib.dr.iastate.edu/ans_air/vol650/iss1/127