Effects of dirty housing and a Salmonella Typhimurium DT104 challenge on pig growth performance, diet utilization efficiency, and gas emissions from stored manure

The objectives of this study were to elucidate the effects of a dirty environment and a Salmonella challenge plus associated environmental contamination on pig growth performance, diet utilization efficiency, and gas emissions (CO₂, NH₃, CH₄, N₂O, and H₂S) from stored manure. Twenty-four weaned barrows, aged 31 d at initiation of the trial, were randomly allotted to 3 different treatments in a completely randomized design. Treatments were: pigs housed in cages with manure removed and cages washed daily (Clean); pigs housed in cages sprayed daily with manure slurry mixtures (Dirty); or pigs challenged with Salmonella Typhimurium DT104 and housed in cages that were not washed, but manure was removed daily (Salmonella challenge). Rectal temperature, body weight, daily feed intake, manure output, manure composition, and gas emissions from stored manure were measured throughout the 24-d animal phase. The Dirty and Salmonella challenge treatments were statistically compared to the Clean treatment to evaluate individual effects. Dirty housing tended to decrease ADG from d 1 to 24 (P = 0.06) but there were no other effects on pig performance compared with the Clean treatment. In contrast, a Salmonella challenge was associated with a marked reduction in each of the measured indicators of pig performance. Salmonella challenge increased the carbon to nitrogen ratio, ether extract, and lignin concentrations in excreted manure (P = 0.02, 0.01, 0.003, respectively), and increased manure and head space temperatures in manure tanks (P < 0.0001). Gas emissions from stored manure of pigs on the Dirty or Salmonella treatments were increased for each of the measured gases as compared to the Clean treatment (P < 0.01) when expressed per unit of BW gain. When gas emissions from manure of pigs housed in the Dirty treatment were expressed per unit of manure volatile solids (VS), they were increased for NH₃, CH₄, and H₂S (P < 0.02). Salmonella challenge was associated with increased emissions of CO₂, and N₂O and decreased emissions of H₂S per kilogram manure VS compared to the Clean treatment (P = 0.06, 0.03, 0.04, respectively). Collectively, these results indicated that a Salmonella challenge and associated housing contamination caused depressed growth rate and increased manure gas emissions, while exposure to a Dirty environment slightly reduced growth performance and clearly increased manure gas emissions per unit of BW gain as compared to Clean control.