Characterization of selected nutrients and bacteria from anaerobic swine manure lagoons on sow, nursery, and finisher farms in the Mid-South USA.

Swine (Sus scrofa domestica) production in the Mid-South USA comprises sow, nursery, and finisher farms. A 2007 packing plant closure started a regional shift from finisher to sow and nursery farms. Changes in manure stored in lagoons and land-applied as fertilizer were expected but were unknown because nutrient and bacterial levels had not been characterized by farm type. The objectives of this study were to quantify selected nutrients and bacteria, compare levels by farm types, and project impacts of production shifts. Nutrients and bacteria were characterized in 17 sow, 10 nursery, and 10 finisher farm lagoons. Total and thermotolerant coliforms, Escherichia coli (Migula) Castellani and Chalmers, Enterococcus spp., Clostridium perfringens (Veillon and Zuber) Hauduroy et al., Campylobacter spp., Listeria spp., and Salmonella spp. were evaluated. Highest levels were from total coliforms (1.4- 5.7x10(5) cfu 100 mL(-1)), which occurred with E. coli, Campylobacter spp., C. perfringens, and Enterococcus spp., in every lagoon and virtually every sample. Lowest levels were from Listeria spp. and Salmonella spp. (<or=1.3x10(2) most probable number [MPN] 100 mL(-1)), detected in 81 and 89% of lagoons and 68 and 64% of samples, respectively. Sow farm levels were higher for all except Listeria spp. and Salmonella spp., which were lower (1.4x10(1) and 2.8x10(1) MPN 100 mL(-1), respectively) and only slightly below their respective levels from nursery farms (1.1x10(2) and 3.4x10(1) MPN 100 mL(-1)). Shifting from finisher to nursery farm would not affect bacterial levels, but shifting to sows would. Either shift would reduce NPK and N:P and suggest modification of nutrient management plans.