Pork production plays a key role in the US economy but faces some challenges that may be resolved using research tools. These include nutrient and waste management and their potential risk to environment, air and water quality issues, and animal welfare concerns. The need to ensure sustainability of farms and consumer positive perceptions compels Federal, State and private agencies to develop regulatory guidelines to reduce negative impacts to environment. Outdoor sustainable pork production units may be one way to address these challenges.; This dissertation evaluated outdoor gestating sows in terms of nitrate nitrogen and phosphorus accumulation in soil, changes in ground cover and botanical composition, productivity of sows and litters and behavior of sows with respect to ambient temperatures, and preference and use of forages by pregnant gilts. The first study compared percent ground cover loss, changes in soil nitrates and phosphorus, and sow behavioral changes with seasons and productivity using 17.5 sow/ha on a burned and non-burned pastures. Soil nitrates tended to be higher when vegetation was dormant with low precipitation. Behavioral measurements indicated that sows spent more (P 0.001) time in the wallow when temperatures were elevated. However, sows rooted more (P 0.02) in cool temperatures. Effects of stocking rates of 17.5 or 35 pregnant sows/ha and dietary protein, 12.6 or 14.7% CP, (in a factorial arrangement of treatments, with 3 replicates) on percentage ground cover, soil nitrates, and sow productivity were evaluated during a second study. More piglets were weaned per sow under a higher stocking rate; however, loss of ground cover was also greater (P 0.001). Soil nitrates tended to be higher for both pastures (P 0.1). Use and preference of four forages by sows was assessed using two experiments in small plots. The first study allowed 2 sows free access to express preference for any of the four forages while the second study had individual sows confined on alfalfa, fescue or buffalograss. Sows grazed clover and alfalfa more intensively than fescue or buffalograss. Implementation of proper management techniques can ensure sustainability of outdoor swine production systems.
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