Effects of dirty housing and a SalmonellaTyphimurium DT104 challenge on pig growth performance, diet utilization efficiency, and gas emissions from stored manure1

The objectives of this study were to elucidate the effects of a dirty environment and a Salmonellachallenge 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 SalmonellaTyphimurium DT104 and housed in cages that were not washed, but manure was removed daily (Salmonellachallenge). 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 Salmonellachallenge 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 Salmonellachallenge was associated with a marked reduction in each of the measured indicators of pig performance. Salmonellachallenge 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 Salmonellatreatments 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). Salmonellachallenge 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 Salmonellachallenge 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.